Space product assurance

Derating - EEE components

Foreword

This Standard is one of the series of ECSS Standards intended to be applied together for the management, engineering and product assurance in space projects and applications. ECSS is a cooperative effort of the European Space Agency, national space agencies and European industry associations for the purpose of developing and maintaining common standards. Requirements in this Standard are defined in terms of what shall be accomplished, rather than in terms of how to organize and perform the necessary work. This allows existing organizational structures and methods to be applied where they are effective, and for the structures and methods to evolve as necessary without rewriting the standards.

This Standard has been prepared and maintained under the authority of the Space Components Steering Board (SCSB) in partnership with the European Space Agency (ESA), national space agencies (NSAs) and the European space industry, reviewed by the ECSS Product Assurance Panel and approved by the ECSS Steering Board.

The end-of-life parameter drifts are not covered by this Standard.

Disclaimer

ECSS does not provide any warranty whatsoever, whether expressed, implied, or statutory, including, but not limited to, any warranty of merchantability or fitness for a particular purpose or any warranty that the contents of the item are error-free. In no respect shall ECSS incur any liability for any damages, including, but not limited to, direct, indirect, special, or consequential damages arising out of, resulting from, or in any way connected to the use of this Standard, whether or not based upon warranty, business agreement, tort, or otherwise; whether or not injury was sustained by persons or property or otherwise; and whether or not loss was sustained from, or arose out of, the results of, the item, or any services that may be provided by ECSS.

Published by:     ESA Requirements and Standards Division
    ESTEC, P.O. Box 299,
    2200 AG Noordwijk
    The
Copyright:     2011© by the European Space Agency for the members of ECSS

Change log

ECSS-Q-60-11A

7 September 2004

First issue

ECSS-Q-30-11A

24 April 2006

Second issue

ECSS-Q-30-11B

Never issued

ECSS-Q-ST-30-11C

31 July 2008

Third issue

Minor editorial changes:

Document converted to new ECSS template,

Bibliography updated (reference to ECSS-S-ST-00 was added and reference to ECSS-E-10-12 and ECSS-Q-30 were deleted because not called from the text)

ECSS-Q-ST-30-11C Rev 1

4 October 2011

Third issue Revision 1

The major changes between ECSS-Q-ST-30-11C and this version are:

- Implementation of Change requests

- Restructuring of document

Detailed Change Record:

Clause 3

Definition of term 3.2.3 "derating" modified

Term 3.2.8 "performance" deleted

Terms for "surge" and "transient" added

Several abbreviated terms in 3.3 added/removed

Clause 5:

Editorial modifications in descriptive text and headers.

Clause 6:

Editorial modifications in descriptive text and headers.

Numbered all Derating tables of clauses 6.xx.2 and added a requirement calling the table.

6.15: Family group codes 04-11 to 04-13 added

6.18: Family group code 14-01 added in

Requirements deleted:

5.4.2d; 6.2.1c; 6.3.1b; 6.5.1a; 6.5.1b; 6.11.1a to d; 6.11.2 req for "max mating and demating cycles"; 6.12.1a; 6.12.2 req for "max mating and demating cycles"; 6.14.1a; 6.14.2.2 req in table on "Zener surge current"; 6.15.a; 6.17.1b; 6.17.1c; 6.18.1a; 6.19.1a; 6.20.1a;'6.21.1a and b; 6.22.1a; 6.23.1a; 6.24.1a and b; 6.25.1c and e to g; 6.26.1.1a; 6.26.1.8, 6.26.1.9a; 6.26.1.10a and b; 6.26.2a; 6.28.1a; 6.29.1a and b; 6.30.1a; 6.31.1a; 6.33.1a to c; 6.34.1a; 6.34.2 table; 6.35.1 table; 6.36a.

Requirements added:

Added requirements with call of the Table with the "Derating of parameters in: 6.2.2a to 6.13.2a; 6.14.2.1a; 6.14.2.2a; 6.15.2a to 6.22.2a; 6.25.2a; 6.26.2.1a to 6.26.2.7a; 6.26.2.8; 6.27.2a to 6.34.2a; 6.34.2.1a; 6.34.2.2a.

Added requirements (moved or new): 5.3.3a to c; 6.2.3a; 6.3.3a and b; 6.4.3a; 6.5.3a and b; 6.11.3a to e; 6.12.3a to c; 6.14.3a to c; 6.15.3a; 6.17.3a to c; 6.18.3a and b; 6.19.3a; 6.20.3a; 6.21.3a and b; 6.22.3a; 6.23.3a; 6.24.2a; 6.24.3a; 6.25.3a to d; 6.26.2.8a and b; 6.28.3a to c; 6.29.3a and b; 6.30.3a; 6.31.1a; 6.32.2b and c; 6.33.3a to c; 6.34.3a to c; 6.34.2.1a; 6.34.2.2a; 6.34.3a to c; 6.35.2; 6.35.3a; 6.36.2a.

Requirements modified:

5.3.2.a, 5.4.2a to c; 5.5.2a; f and g; 6.2.2 table; 6.14.2.1 table; 6.17.1a first sentence deleted; 6.18.2 table; 6.19.2 table; 6.20.2 table; 6.25.1a and b; 6.25.2 table; 6.26.1.2 to 6.26.1.7 table modified and moved; 6.29.2 table; 6.30.2 table; 6.31.2 table; 6.32.2 table split and modified.

Introduction

This Standard specifies derating requirements applicable to electronic, electrical and electromechanical components.

Derating is a long standing practice applied to components used on spacecrafts. Benefits of this practice are now proven, but for competitiveness reasons, it becomes necessary to find an optimized reliability. Too high a derating can lead to over-design, over-cost and over-sizing of components, the direct consequence being excess volume and weight. The aim is to obtain reliable and high performance equipment without over-sizing of the components. For this reason and if possible, this Standard provides derating requirements depending on mission duration and mean temperature, taking into account demonstrated limits of component capabilities.

Scope

This Standard applies to all parties involved at all levels in the realization of space segment hardware and its interfaces.

The objective of this Standard is to provide customers with a guaranteed performance and reliability up to the equipment end-of-life. To this end, the following are specified:

Load ratios or limits to reduce stress applied to components;

Application rules and recommendations.

This standard may be tailored for the specific characteristics and constraints of a space project, in accordance with ECSS-S-ST-00.

Normative references

The following normative documents contain provisions which, through reference in this text, constitute provisions of this ECSS Standard. For dated references, subsequent amendments to, or revisions of any of these publications do not apply. However, parties to agreements based on this ECSS Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references the latest edition of the publication referred to applies.

ECSS-S-ST-00-01	ECSS system - Glossary of terms
ECSS-Q-ST-60	Space product assurance - Electrical, electronic and electromechanical (EEE) components
ESCC 2269010	Evaluation test programme for monolithic microwave integrated circuits (MMICS)
ESCC 2265010	Evaluation Test Programme for Discrete Microwave Semiconductors

Terms, definitions and abbreviated terms

Terms from other standards

For the purpose of this Standard, the terms and definitions from ECSSST0001 apply.

Terms specific to the present standard

ambient temperature
temperature surrounding a component

case temperature
temperature on the component package surface

derating
process of designing a product such that its components operate at a significantly reduced level of stress to increase reliability and to insure useful life and design margins.

hot spot temperature
highest measured or predicted temperature within any component

junction temperature
highest measured or predicted temperature at the junction within a semiconductor or micro-electronic device

Predicted temperature can be taken as Tcase + thermal resistance between junction and case times actual power (Watt) of the device.

load ratio
permissible operating level after derating has been applied; given as a percentage of a parameter rating

operating conditions
parameter stress and environment (temperature, vibration, shock and radiation) in which components are expected to operate

term "performance" deleted
RadPack
package designed to provide some form of radiation protection

rating
maximum parameter value specified and guaranteed by the component manufacturer and component procurement specification

Rating is considered as a limit not to be exceeded during operation and constitutes in most cases the reference for derating.

surge
strong rush or sweep

[Collins dictionary and thesaurus]

transient
brief change in the state of a system

[Collins dictionary and thesaurus]

Abbreviated terms

For the purpose of this Standard, the abbreviated terms from ECSSSST0001 and the following apply:

Abbreviation	Meaning
A/D	analog to digital
ASIC	application specific integrated circuit
C	capacitance
DRAM	dynamic random access memory
EEPROM	electrical erasable programmable read only memory
EPROM	erasable programmable read only memory
ESCC	European Space Component Coordination
ESR	equivalent series resistance
f	frequency
FET	field effect transistor
GaAs	gallium arsenide
ISO	International Organization for Standardization
InP	indium posphide
LED	light emitting diode
MOS	metal on silicon
MIL (spec)	specification of the US Department of Defense
MMIC	monolithic microwave integrated circuit
NASA	National Aeronautics and Space Administration
P	power
PROM	programmable read only memory
RadHard	radiation hardened
Ri	insulation resistance
RF	radio-frequency
SEBO	single event burn-out
SEGR	single event gate rupture
Si, SiGe	silicon, silicon germanium
SOA	safe operating area
SRAM	static random access memory
Tj	junction temperature
Tjmax	absolute maximum rated junction temperature
Top	operating temperature
VCE	collector-emitter voltage

User responsibility

The user of this Standard shall verify that the ordered assurance level of procured components is compatible with the intended application.

Derating

Overview

The term derating refers to the intentional reduction of electrical, thermal and mechanical stresses on components to levels below their specified rating. Derating is a means of extending component life, increasing reliability and enhancing the end-of-life performance of equipment.

Derating participates in the protection of components from unexpected application anomalies and board design variations.

The load ratios or limits given in clause 6 were derived from information available at the time of writing this Standard and do not preclude further derating for specific applications.

This Standard also defines how to handle transients.

Principles of derating

The component parameter strength defines the limits and the performance component technology in the particular application and varies from manufacturer to manufacturer, from type to type, and from lot to lot and can be represented by a statistical distribution. Likewise, component stress can be represented by a statistical distribution. Figure 51 illustrates the strength of a component and the stress applied at a given time, where each characteristic is represented by a probability density function.

A component operates in a reliable way if its parameter strength exceeds the parameter stress. The designer should ensure that the stress applied does not exceed the component parameter strength. This is represented by the intersection (shaded area) in Figure 51. The larger the shaded area, the higher the possibility of failure becomes.

There are two ways, which may be used simultaneously, in which the shaded area can be decreased:

Decrease the stress applied (which moves the stress distribution to the left).

Increase the component parameter strength (by selecting over-sized components) thereby moving the strength distribution to the right.

The goal is to minimize the stress-to-strength ratio of the component. Derating moves the parameter stress distribution to the left while the selection processes applied to the components for space applications contribute to moving the parameter strength distribution to the right. The selection processes also reduce the uncertainty associated with the component parameter strength.

Derating reduces the probability of failure, improves the end-of-life performance of components and provides additional design margins.

Another effect of derating is to provide a safety margin for design. It allows integrating parameter distribution from one component to another, and from one procurement to another.

Figure 51: Parameter stress versus strength relationship

Applicability and component selection

Overview

This Standard applies to all components, selected for space applications, that are used for a significant duration. The meaning of “significant duration” is a period that contributes to the component life, for instance, one month is considered to be a significant duration. These requirements apply to screened components procured in accordance with approved space specifications.

This Standard only applies to approved components for which quality was proven after rigorous testing in accordance with ECSS-Q-ST-60.

Derating applies on normal operational conditions, where “normal” is opposed to “fault” and “Operational” indicates all functional modes of the unit.

Derating analysis is performed at the equipment maximum hot acceptance temperature, unless otherwise specified.

Requirements

Derating shall be applied in consideration of temperature limits recommended by the manufacturer.
The derating requirements of this Standard shall not be used as a justification to upgrade the quality level of components.
The derating requirements shall be taken into account at the beginning of the design cycle of an equipment for any consequential design trade-off to be made. Specific attention shall be paid to, for example, breadboards and engineering models where parameter derating was not considered.
Component families and groups excluded in this Standard are due to the lack of experimental data and failure history. For these components, the user shall consult a component design and reliability specialist to apply the requirements of this Standard.
Components may be excluded from this Standard if they are used for short durations of less than one month provided the device ratings are not exceeded; for example, components used in solar generator deployment systems, redundancy commutation and launchers (except in some specific cases, noted family by family). In these cases, the designer shall ensure that the applied stress level does not exceed the component maximum rating.
The derating requirements are not applicable to test conditions (e.g. circuit or equipment level qualification and EMC) for which the maximum ratings shall not be exceeded.
Derating requirements are not applicable to fault conditions, for which the maximum rating shall not be exceeded, with the exception defined in 5.3.2h.
Where components are required to operate in protection mode or in fail-safe mode in order to prevent failure propagation (e.g. short-circuit protection), the components concerned shall meet the derating requirements and application rules when performing the protection or fail-safe function under the worst failure case (i.e. highest stress applied to the components that can last throughout the mission).

Requirements ESCC exceptions

For a particular type or manufacturer, when a specific derating rule is defined in the appendix of the approved ESCC detail specification issued by the ESCC Executive, it shall take precedence over the generic requirement of this standard.
Users shall check for application the actual status of the ESCC Derating exceptions on the following ESCC web site page: ESCC Derating deviations

A list of the ESCC detail specifications applicable at the time of publication and containing deviations to general derating requirements of this standard is available in informative Annex B.

Users shall clearly identify in the Parts Stress Analysis document the list of the ESCC Derating exceptions taken into consideration in their analysis.

Derating parameters

Overview

Derating requirements are provided in clause 6 for each component family.

For each category, the parameters to be derated are identified. The main parameters to be derated are:

junction or case temperature;

power (rating, dissipation);

voltage;

current.

The parameters to be derated depend on component type.

A stress balancing concept offers flexibility between one stress versus another (voltage and temperature). In some cases, e.g. resistors, derating has a direct impact on component performance.

Requirements for transient and surge conditions

For transient or surge conditions, if ratings are provided, the same derating figures as for steady-state equivalent parameters shall be used.
For transient or surge conditions, if ratings are not provided, then it shall be assured that the transient or surge values are below the steady-state specified maximum ratings.
For all periodic signals or transient conditions which are repeated or made incessant, the steady-state derating figures shall apply.
<<deleted>>
As an exception in case clause 5.4.2c is not compatible for specific repeated and incessant transient use conditions, for the parts types and parameters listed, load ratio shall not exceed the steady state derated values +10 % or 80 % of the steady state rated values, which ever is lower:

Connectors: voltage, current
Ceramic Capacitors: voltage
Resistors: current
Diodes: current
Transistors_ bipolar , MOSFETs, power FETs: current.

Additional rules and recommendations

Overview

In addition to strict derating requirements, some application rules and recommendations are given in this Standard to achieve the suitable reliability. This additional application rules and recommendations are listed separately in the clauses titled “Additional requirements not related to derating”. This disposition is valid until other adequate ECSS documents can host these additional clauses.

Where radiation sensitive components are identified, it is the user’s responsibility that the chosen component technologies are suitable and that the mitigation factors, such as shielding, meet the customer’s requirement. The electrical derating shall be in accordance with this Standard.

Tables for load ratios or limits

Overview

This clause provides the load ratios or limits.

They are also available on the World Wide Web at the following address:

https://escies.org

Abbreviations used in the tables are explained in clause 3.

Annex A contains a complete listing of the family and group codes for parts that are referred to in this Standard.

Annex B contains ESCC exceptions at date of publication of this standard.

Capacitors: ceramic - family-group code: 01-01 and 01-02

General

The capacitor stress sum value of steady-state voltage, AC voltage shall not exceed the load ratios specified hereunder. For transients refer to clause 5.4.
Multilayer capacitors with a DC voltage rating less than 100 V may be used in low voltage (less than 10 V) continuous applications provided they have been submitted to a low voltage (1,5 V) 85 % humidity at 85 C test or other approved method.
<<deleted>>
Internal heating due to ESR can increase ageing and should be taken into account by applying a margin in temperature. Where ESR is not known at the frequency of a ripple current, an extrapolation of the ESR value and resonance (from manufacturer’s or test data) should be made where possible.

Derating

Parameters of capacitors from family-group code 01-01 and 01-02 shall be derated as per Table 61.
Table 61: Derating of parameters for capacitors family-group code 01-01 and 01-02

The dV/dt rating capability of the capacitors shall be respected.

Capacitors: solid tantalum - family-group code: 01-03

General

The capacitor stress sum value of steady-state voltage and AC voltage shall not exceed the load ratio specified hereunder. For transients refer to clause 5.4.
<<deleted - moved to 6.3.3a>>
Surge current shall be derated to 75 % of the Isurge max. Isurge max is defined as Vrated/(ESR+Rs). Vrated is the maximum rated voltage, ESR is the maximum specified value and Rs is the value of series resistance specified in the circuit for surge current testing as defined in the applicable procurement specification.
Reverse voltage shall not exceed 75 % of the manufacturer’s specified maximum value for the reverse voltage.
Ripple power shall never exceed 50 % of the manufacturer’s specified maximum value.
Internal heating due to ESR can increase ageing and should be taken into account by applying a margin in temperature. Where ESR is not known at the frequency of a ripple current, an extrapolation of the ESR value and resonance (from manufacturer’s or test data) should be made where possible.

Derating

Connectors - family-group code: 02-01, 02-02, 02-03, 02-07 and 02-09

General

<<deleted - moved to 6.11.3a>>
<<deleted - moved to 6.11.3b>>
<<deleted - moved to 6.11.3c>>
<<deleted - moved to 6.11.3d>>

Derating

Parameters of connectors from family-group code 02-01, 02-02, 02-03, 02-07 and 02-09 shall be derated as per Table 610.
Table 610: Derating of parameters for connectors family-group code 02-01, 02-02, 02-03, 02-07 and 02-09

Parameters	Load ratio or limit
Working voltage	50 % of specified voltage at any altitude (pin-to-pin and pintoshell).
Current	50 %
Hot spot temperature	30 C below maximum rated temperature.
<<deleted>>	<<deleted - moved to 6.11.3e>>

For power connectors, power and return lines shall be separated by at least one unassigned contact to reduce the short-circuit risk.
Connector savers shall be used during testing of equipment to minimize number of mating and de-mating cycles.
When multi-pin connectors are close to one another, they shall be configured such that mating with a wrong connector is not possible or the contact assignments shall be chosen such that mating with a wrong connector does not cause damage to the unit itself nor to any other element of the system.
The connector and its constituent parts shall be from the same manufacturer.
Maximum mating and de-mating cycles shall be limited to 50 cycles.

Connectors RF - family-group code: 02-05

General

<<deleted - moved to 6.12.3a>>

Derating

Parameters of connectors RF from family-group code 02-05 shall be derated as per Table 611.
Table 611: Derating of parameters for connectors RF family-group code 02-05

Parameters	Load ratio or limit
RF power	75 %
Working voltage	50 % of specified voltage at any altitude (pin-to-pin and pin-to-shell).
Hot spot temperature	30 C below maximum rated temperature.
<<deleted>>	<<deleted - moved to 6.12.3c>>

Connector savers shall be used during testing of equipment to minimize number of mating and demating cycles.
RF power shall be limited such that a 6 dB margin exists before the onset of multipactor.
Maximum mating and de-mating cycles shall be limited to 50 cycles.

Piezo-electric devices: crystal resonator - family-group code: 03-01

General

No general clause.

Derating

Parameters of piezo-electric devices from family-group 03-01 shall be derated as per Table 612.
Table 612: Derating of parameters for piezo-electric devices family-group code 03-01

Parameters	Load ratio or limit
Drive level	25 % power rated drive level (superseded by manufacturer required minimum drive level if not compatible).

No additional requirement.

Diodes - family-group code: 04-01, 04-02, 04-03, 04-04, 04-06, 04-08, 04-10 and 04-14

General

<<deleted - moved to 6.14.3a and 6.14.3b>>

Derating

Diode (signal/switching, rectifier, including Schottky, pin derating table

Parameters of Diode (signal/switching, rectifier including Schottky, pin) shall be derated as per Table 613.
Table 613: Derating of parameters for Diode (signal/switching, rectifier including Schottky, pin)

Parameters	Load ratio or limit
Parameters	Load ratio or limit	Forward current (IF):	75%
Reverse voltage (VR)	75 %
Dissipated power (PD)	50 % (only if dissipated power is defined by the manufacturer)
Junction temperature (Tj )	110 C or Tj max - 40 C (whichever is lower).

Diode (Zener, reference, transient suppression) derating table

Parameters of Diode (Zener, reference, transient suppression) shall be derated as per Table 614.
Table 614: Derating of parameters for Diode (Zener, reference, transient suppression)

Parameters	Load ratio or limit
Parameters	Load ratio or limit	<<deleted>>	<<deleted>>
Dissipated power (PD) or Current (IZM)	65 %
Junction temperature (Tj )	110 C or Tj max - 40 C (whichever is lower)

Some diodes can be radiation sensitive: the issue shall be recorded in the design file and the components selection shall be reviewed and approved as described in ECSS-Q-ST-60.
Where power cycling is critical this should be considered.
The dV/dt rating capability of the diodes shall be respected.

Diodes: RF/microwave - family-group code: 04-05, 04-11 to 04-13, 04-15, 04-16 and 0417

General

<<deleted - moved to 6.15.3a.>>

Derating

Parameters of Diodes from family-group code 04-05, 04-11 to 04-13, 04-15, 04-16 and 0417 shall be derated as per Table 615.
Table 615: Derating of parameters for Diodes family-group code 04-05, 04-11 to 04-13, 04-15, 04-16 and 0417

Parameters	Load ratio or limit
Forward current	50 %
Reverse voltage (VR)	75 %
Dissipated power (PD)	65 %
Junction temperature (Tj )	110 C or Tj max - 40 C (whichever is lower)
NOTE 1: Forward current is not applicable to varactors. NOTE 2: Reverse voltage is not applicable to Gunn diodes.

Load ratio or limit

Special conditions

Maximum operating voltage (1)

50 % of the applied insulation test voltage (2)

(1) Between winding-winding and between windings-case. The maximum operating voltage shall include DC, AC peak or combined.

(2) <<deleted - moved to 6.18.3b>>

Each discrete cell (capacitors, resistors, diodes and transistors) constituting analogue custom MMICs shall be derated in accordance with this document’s requirements for the applicable family. For digital cells, apply the derating rules applicable to integrated circuits.
When operational reliability data is available, the compression level shall be derated to 2 dB under the highest compression level showing no drift. MMICs having no compression data shall not be submitted to more than 1 dB of compression.

Some MMICs can be radiation sensitive: the choice of MMICs shall be based on suitability and application. Justification shall be in accordance with ECSS-Q-ST-60 and provided in accordance with this Standard, and at the design reviews

Integrated circuits: miscellaneous - family-group code: 08-99

General

<<deleted - modified and moved to 6.24.2a>>
<< deleted - moved to 6.24.3a>>

Derating

For all ICs not considered in the previous subgroups, the following derating rules shall be followed:

Manufacturer’s derating values.
Junction temperature: 110 C or Tj max - 40 C, whichever is lower.
For the part of the IC similar to logic ICs, apply the derating rules for logic subgroups, for the part similar to linear ICs, apply the derating rules for linear subgroups and so forth.

Some integrated circuits can be radiation sensitive: this shall be recorded and approved in accordance with ECSS-Q-ST-60.

Relays and switches - family-group code: 09-01, 0902 and 16-01

General

The coil supply voltage shall be within the specified voltage range or between the specified rated and the maximum coil voltage. When no minimum coil voltage is provided, the coil voltage shall be between 110 % of the maximum latch or reset or pick-up voltage over the full temperature range and the maximum coil voltage.

Latch or reset voltage are specified for latching device, pick-up voltage is specified for non-latching devices.

The minimum coil pulse duration for latching relays shall be 3 times the latch time (tL) or 40 ms, whichever is greater.
<<deleted - moved to 6.25.3a>>
Rated contact load voltage should not be exceeded since it has a strong impact on the contact current: this shall be recorded and approved in accordance with ECSS-Q-ST-60.
<<deleted - moved to 6.25.3b>>
<<deleted - moved to 6.25.3c.>>
<<deleted - moved to 6.25.3d.>>

Derating

Parameters of Relays and switches from family-group code 09-01, 0902 and 16-01 shall be derated as per Table 623.
Table 623: Derating of parameters for Relays and switches family-group code 09-01, 0902 and 16-01

Parameters	Load ratio or limit
Contact current Resistive load	![Image](/img/ECSS-Q-ST-30-11C/media/image13.png)
	Number of operations less than 100 (including integrating and testing) When the specified overload current is rated at twice the rated contact current, the rated contact current may be used. When the specified overload current is rated at 4 times the rated contact current, twice the rated contact current may be used.
Inductive load	50 % of inductive load if specified, or 40 % of resistive load otherwise. If an arc suppressor or snubber system is used, the load factor for resistive load may be applied.
Motor load	50 % of motor load if specified, or 20 % of resistive load otherwise
Filament load	10 % of resistive load.
Minimum contact current	For rated contract current (ICR) 1 A, no limit needs to be considered. For 1 A < ICR 5 A, the current shall be greater than 10 mA. For ICR > 5 A, the current shall be greater than 10 % of the rated current.
Surge contact current (ISCR)	When the surge duration 10 s, the surge contact current shall not exceed 4 times the rated contact current. For surge duration > 10s : where: I = Surge current Ir = Rated current tp = Surge duration

Current derating does not apply to contacts that only carry current and do not switch it or to contacts that switch at zero current. In the latter case, the number of operations is limited to the qualified number of operations.
A double throw contact shall not be used to switch a load (movable contact) between a power supply and ground (stationary contacts). This type of configuration may be accepted in the following conditions:

when switching off the power supply the other stationary contact is not connected to ground, or
the potential difference between stationary contacts is less than 10 V and the switched current less than 0,1 A. Paralleled relays shall not be used to increase current switching capabilities of contacts. When relays are paralleled for redundancy, in order to increase the system’s reliability, the sum of the paralleled currents shall not exceed the contact current rating.
Suppression diodes shall not be used inside relays.

Resistors - family-group code: 10-01 to 10-11

General

No general clause.

<<deleted>>

<<deleted - moved as Note to derating tables Table 624 to Table 630>>
<<6.26.1.2 to 6.26.1.7 deleted - modified and moved to 6.26.2.1 to 6.26.2.7>>

<<6.26.1.8 to 6.26.1.10 deleted>>

Derating

<<deleted - moved to 6.26.2.8a including the derating table>>

Metal film precision resistor (type RNC, except RNC 90) derating table

Parameters of Metal film precision resistor (type RNC, except RNC 90) shall be derated as per Table 624.
Table 624: Derating of parameters for Metal film precision resistor (type RNC, except RNC 90)

Parameters	Load ratio or limit
Voltage	80 %
rms Power	50 % up to 125 C and further decreasing to 0 % at 150 C
NOTE: The mentioned temperatures cited refer to case temperatures.

Metal film semi-precision resistor (type RLR) derating table

Parameters of Metal film semi-precision resistor (type RLR) shall be derated as per Table 625.
Table 625: Derating of parameters for Metal film semi-precision resistor (type RLR)

Parameters	Load ratio or limit
Voltage	80 %
rms Power	50 % up to 70 C and further decreasing to 0 % at 125 C
NOTE: The mentioned temperatures cited refer to case temperatures.

Foil resistor (type RNC 90) derating table

Parameters of Foil resistor (type RNC 90) shall be derated as per Table 626.
Table 626: Derating of parameters for Foil resistor (type RNC 90)

Parameters	Load ratio or limit
Voltage	80 %
rms Power	50 % up to 70 C and further decreasing to 0 % at 125 C
NOTE: The mentioned temperatures cited refer to case temperatures.

Wire-wound high precision resistor (type RBR 56) derating table

Parameters of Wire-wound high precision resistor (type RBR 56) shall be derated as per Table 627.
Table 627: Derating of parameters Wire-wound high precision resistor (type RBR 56)

Parameters	Load ratio or limit
Voltage	80 %
rms Power (type RBR 56)	Wire-wound for all tolerances: 50 % up to 115 C, decreasing to 0 % at 130 C
NOTE: The mentioned temperatures cited refer to case temperatures.

Wire-wound power resistor (type RWR, RER) derating table

Parameters of Wire-wound power resistor (type RWR, RER) shall be derated as per Table 628.
Table 628: Derating of parameters for Wire-wound power resistor (type RWR, RER)

Parameters	Load ratio or limit
Voltage	80 %
rms Power	60 % up to 25 C, decreasing to 0 % at 175 C
NOTE: The mentioned temperatures cited refer to case temperatures.

Chip resistor (RM), network resistor derating table

Parameters of Chip resistor (RM), network resistor shall be derated as per Table 629.
Table 629: Derating of parameters for Chip resistor (RM), network resistor

Parameters	Load ratio or limit
Voltage	80 %
rms Power	50 % up to 85 C, decreasing to 0 % at 125 C
NOTE: The mentioned temperatures cited refer to case temperatures.

Carbon composition resistor table

Parameters of Carbon composition resistor shall be derated as per Table 630.
Table 630: Derating of parameters for Carbon composition resistor

Parameters	Load ratio or limit
Voltage	80 %
rms Power	50 % up to 70 °C, decreasing to 0 % at 100°C
NOTE: The mentioned temperatures cited refer to case temperatures.

Heaters

Actual rated power shall be specified in the applicable heater design drawing. It shall be determined from the specified heating area (s) in cm2 taking into account the thermal properties of the mounted heater in the application.
Parameters of heaters shall be derated as per Table 631.
Table 631: Derating of parameters for Heaters

Parameters	Load ratio or limit
Actual rated power (W)	50 %

No additional requirement.

Thermistors - family-group code: 11-01 to 11-03

General

No general clause.

Derating

Parameters of Thermistors from family-group code 11-01 to 11-03 shall be derated as per Table 632.
Table 632: Derating of parameters for Thermistors family-group code 11-01 to 11-03

Parameters	Load ratio or limit
Power	50 % of the maximum power

No additional requirement.

Transistors: bipolar - family-group code: 12-01 to 12-04 and 12-09

General

<<deleted - moved to 6.28.3a>>

Derating

Parameters of Transistors from family-group code 12-01 to 12-04 and 12-09 shall be derated as per Table 633.
Table 633: Derating of parameters for Transistors family-group code 12-01 to 12-04 and 12-09

Parameters	Load ratio or limit
Collector-emitter voltage (VCE0)	75 %
Collector-base voltage (VCB0)	75 %
Emitter-base voltage (VEB0)	75 %
Collector current (IC max)	75 %
Base current (IB max), if specified	75 %
Power (PD)	65 % of maximum power
Junction temperature (Tj )	110 C or Tj max - 40 C (whichever is lower).
<<Notes deleted and moved to 6.28.3b and 6.28.3c>>

Some transistors can be radiation sensitive: the issue shall be recorded in the design file and the components selection shall be reviewed and approved as described in ECSS-Q-ST-60.
The designer should refer to the SOA
Where power cycling is critical this should be considered

Transistors: FET - family-group code: 12-05 and 12-06

General

<<deleted - moved to 6.29.3a>>
<<deleted - moved to 6.29.3b>>

Derating

Parameters of Transistors from family-group code 12-05 and 12-06 shall be derated as per Table 634.
Table 634: Derating of parameters for Transistors family-group code 12-05 and 12-06

Parameters	Load ratio or limit
Drain to source voltage (VDS)	80 % of rated, or the SEE safe operating area (VDS versus VGS), whichever is lower
Gate to source voltage (VGS)	75% of rated, or the SEE safe operating area (VDS versus VGS), whichever is lower
Drain current (IDS)	75 %
Power dissipation (PD) max	65 % max
Junction temperature (Tj )	110 C or Tj max - 40 C (whichever is lower)

Only SEE radiation characterized MOSFETs shall be used in space applications.
Where power cycling is critical this should be considered.

Transistors: RF: bipolar - family-group code: 12-10 and 12-13

General

<<deleted - moved to 6.30.3a.>>

Derating

Parameters of Transistors from family-group code 12-10 and 12-13 shall be derated as per Table 635.
Table 635: Derating of parameters for Transistors family-group code 12-10 and 12-13

Parameters	Load ratio or limit
Collector-emitter voltage (VCE)	75 %
Collector-base voltage (VCB)	75 %
Emitter-base voltage (VEB)	75 %
Collector current (IC)	75 %
Base current (IB), if specified	75 %
Power dissipation (PD)	65 % or limited by the derating on operating temperature.
Junction temperature (Tj )	110 C or Tj max - 40 C (whichever is lower) for Si and SiGe bipolar transistors. 115 C or Tj max - 25C (whichever is lower) for GaAs and InP bipolar transistors. ESCC Exception: 125 °C for GaAs or InP, providing # that the specified maximum rating Tmax 150 °C , # that Devices or Processes are supported by ESCC 2269010 and 2265010 evaluation program or equivalent # that the related evaluation reports are available
NOTE When supported by reliability data, the compression level (including worst case modulation peak compression) is derated to 2 dB under the highest compression level showing no drift. No compression levels exceeding 1 dB are applied to Bipolar transistors without compression data.

Some transistors can be radiation sensitive: the issue shall be recorded in the design file and the components selection shall be reviewed and approved as described in ECSS-Q-ST-60.

Transistors: RF: FET - family-group code: 12-12, 12-14, 12-15(FET) and 12-16(FET)

General

<<deleted - moved to 6.31.3a.>>

Derating

Parameters of Transistors from family-group code 12-12, 12-14, 12-15(FET) and 12-16(FET)shall be derated as per Table 636.
Table 636: Derating of parameters for Transistors family-group code 12-12, 12-14, 12-15(FET) and 12-16(FET)

Parameters	Load ratio or limit
Drain to source voltage (VDS)	75 %
Gate to source voltage (VGS)	75 %
Gate to drain voltage (VGD)	75 %
Drain current (IDS)	75 %
Power dissipation (PD)	80 % or limited by the derating on operating temperature.
Junction temperature (Tj )	110 C or Tj max - 40 C (whichever is lower) for Si FET transistors. 115 C or Tj max - 25 C (whichever is lower) for GaAs and InP FET transistors. ESCC Exception : 125°C for GaAs or InP, providing # that the specified maximum rating Tmax 150 °C , # that Devices or Processes are supported by ESCC 2269010 and 2265010 evaluation program or equivalent # that the related evaluation reports are available.
NOTE: When supported by reliability data, the compression level (including worst case modulation peak compression) is derated to 2 dB under the highest compression level showing no drift. No compression levels exceeding 1 dB are applied to FETs without compression data.

Some transistors can be radiation sensitive: this issue shall be recorded in the design file and the components selection shall be reviewed and approved as described in ECSS-Q-ST-60.

Wires and cables - family-group code: 13-01 to 13-03

General

No general clause.

Derating

Parameters of Wires and cables from family-group code 13-01 to 13-03 shall be derated as per Table 637.
The derating on current for bundles (IBW) with N wires shall be calculated as IBW = ISW × K, with ISW the derated current for single wire and K as per Table 638.
In case of wires in cold redundancy or wires non used in the same bundle (some with current, others without current) the number of wires to take into account is calculated as follows: N equivalent bundle = N wires with current + 0,5 x N wires without current with IBW which shall not overpass ISW.
Table 637: Derating of parameters for Wires and cables family-group code 13-01 to 13-03

Parameters	Load ratio or limit
Voltage	50 %
Wire size (AWG)	32	30	28	26	24	22	20	18	16	14	12	10	8	6	4
Maximum current for single wire Cu (Isw) (A) a	1,2	1,3	1,5	2,5	3,5	5	7,5	10	13	17	25	32	45	60	81
Maximum current for single wire Al (Isw) (A) a						4	6	8	10,4	13,6	18,4	25,6	36
Wire surface temperature	Manufacturer’s maximum rating Tmax -50 C .
a for ambient temperature of 40 °C.

Table 638: Bundle factor K for calculation of the derated current for each individual wire in bundles of N wires

Wires AWG 12 to AWG 32		Wires AWG 0 to AWG 10
Number of wires (N)	K	Number of wires (N)	K
1 < N 3 3 < N 7 7 < N 19 19 < N 331	1,1 - (0,1 × N) 1,01 - (0,07 × N) 0,81 - [0,15 × ln(N)] 0,59 - [0,076 × ln(N)]	1 < N 3 3 < N 7 7 < N 52 52 < N 331	1,1 - (0,1 × N) 1,01 - (0,07 × N) 0,81 - [0,15 × ln(N)] 0,467 - [0,0632 × ln(N)]
IBW: maximum current for an individual wire in a bundle. ISW: maximum current for a single wire as given in the derating Table 637. ln: Natural log.

No additional requirement.

Opto-electronics - family-group code: 18-01 to 18-05

General

<<deleted - moved to 6.33.3a>>
<<deleted - moved to 6.33.3b>>
<<deleted - moved to 6.33.3c>>

Derating

Parameters of Opto-electronics from family-group code 18-01 to 18-05 shall be derated as per Table 639.
Table 639: Derating of parameters for Opto-electronics family-group code 18-01 to 18-05

Parameters	Load ratio or limit
Light emitting diode:
Forward current	Manufacturer recommended value, or derate to 50 % if not available
Reverse voltage	Derate to 75 %
Photo transistor:
Maximum collector current	Derate to 80 %
Maximum collector-emitter voltage	Derate to 75 %
Light emitting diode and photo transistor:
Junction temperature (Tj )	110 C or Tj max -40 C (whichever is lower)

Light emitting diodes can be radiation sensitive, in particular, there is a high sensitivity to proton displacement damage: this issue shall be recorded in the design file and the components selection shall be reviewed and approved as described in ECSS-Q-ST-60.
Opto-couplers can be radiation sensitive, in particular, operation at low diode currents increases radiation sensitivity: this issue shall be recorded in the design file and the components selection shall be reviewed and approved as described in ECSS-Q-ST-60.
Photo-transistors can be radiation sensitive: this issue shall be recorded in the design file and the components selection shall be reviewed and approved as described in ECSS-Q-ST-60.

RF passive components: family-group code: 30-01, 30-07, 30-09, 30-10 and 30-99

General

<<deleted - moved to 6.34.3a.>>

Derating

<<Table deleted - Requirement for RF power moved to 6.34.3b>>

Low power < 5 W

Parameters of RF passive components from family-group code 30-01, 30-07, 30-09, 30-10 and 30-99 shall be derated for Low power < 5 W as per Table 640 and for High power 5 W as per Table 641.
Table 640: Derating of parameters for RF passive components from family-group code 30-01, 30-07, 30-09, 30-10 and 30-99 - Low power < 5 W

Parameters	Load ratio or limit
RF power	75 %
Hot spot temperature	30 C below maximum rated temperature.

High power 5 W

Parameters of RF passive components from family-group code 30-01, 30-07, 30-09, 30-10 and 30-99 shall be derated for High power 5 W as per Table 641.
Table 641: Derating of parameters for RF passive components from family-group code 30-01, 30-07, 30-09, 30-10 and 30-99 - Low power 5 W

Parameters	Load ratio or limit
RF power	75 %
Hot spot temperature	5 °C below qualification temperature

For connectorized components, connector savers shall be used during testing of equipment to minimize number of mating and demating cycles.
RF power shall be limited such that a 6 dB margin exists before the onset of multipactor.
Maximum mating and de-mating cycles shall be limited to 50 cycles.

Fibre optic components: fibre and cable: family-group-code: 27-01

General

<<deleted - Table moved to Table 642>>

Derating

No derating clause.

Parameters of Fibre optic components shall be derated as per Table 642.
Table 642: Derating of parameters for Fibre optic components

Parameters	Load ratio or limit
Bend radius	200 % of the minimum value
Cable tension	50 % of the rated tensile strength
Fibre tension	20 % of the proof test

Hybrids

<<Requirement 6.36a. from previous issue moved to 6.36.2a>>

General

<<No general clause>>

Derating

For hybrids, individual components shall be in conformance with their respective derating rules.

No additional requirement.

ANNEX(informative)Family and group codes

This annex contains an extract from the European preferred parts list (EPPL) and it lists all the parts referred to in this Standard providing their family and group codes.

Family code	Group code	Family	Group
01	01	Capacitors	Ceramic
01	02	Capacitors	Ceramic Chip
01	03	Capacitors	Tantalum solid
01	04	Capacitors	Tantalum non-solid
01	05	Capacitors	Plastic metallized
01	06	Capacitors	Glass
01	07	Capacitors	Mica and reconstituted mica
01	10	Capacitors	Feedthrough
01	11	Capacitors	Semiconductor
01	99	Capacitors	Miscellaneous
02	01	Connectors	Circular
02	02	Connectors	Rectangular
02	03	Connectors	Printed circuit board
02	07	Connectors	Microminiature
02	09	Connectors	Rack and panel
03	01	Piezo-electric devices	resonator
04	01	Diodes	Switching
04	02	Diodes	Rectifier
04	03	Diodes	Voltage regulator
04	04	Diodes	Voltage reference/zener
04	05	Diodes	RF/microwave Schottky - Si
04	06	Diodes	Pin
04	08	Diodes	Transient suppression
04	10	Diodes	High voltage rectifier
04	11	Diodes	Microwave varactor - GaAs
04	12	Diodes	Step recovery
04	13	Diodes	Microwave varactor - Si
04	14	Diodes	Current regulator
04	15	Diodes	Microwave Schottky - GaAs
04	16	Diodes	RF/microwave - PIN
04	17	Diodes	Microwave Gunn - GaAs
05	01	Filters	Feedthrough
06	01	Fuses	All
07	01	Inductors	RF coil
07	02	Inductors	Cores
07	03	Inductors	Chip
08	10	Microcircuits	Microprocessors/microcontrollers/peripherals
08	20	Microcircuits	Memory SRAM
08	21	Microcircuits	Memory DRAM
08	22	Microcircuits	Memory PROM
08	23	Microcircuits	Memory EPROM
08	24	Microcircuits	Memory EEPROM
08	29	Microcircuits	Memory others
08	30	Microcircuits	Programmable logic
08	40	Microcircuits	ASIC technologies digital
08	41	Microcircuits	ASIC technologies linear
08	42	Microcircuits	ASIC technologies mixed analogue/digital
08	50	Microcircuits	Linear operational amplifier
08	51	Microcircuits	Linear sample and hold amplifier
08	52	Microcircuits	Linear voltage regulator
08	53	Microcircuits	Linear voltage comparator
08	54	Microcircuits	Linear switching regulator
08	55	Microcircuits	Linear line driver
08	56	Microcircuits	Linear line receiver
08	57	Microcircuits	Linear timer
08	58	Microcircuits	Linear multiplier
08	59	Microcircuits	Linear switches
08	60	Microcircuits	Linear multiplexer/demultiplexer
08	61	Microcircuits	Linear analog to digital converter
08	62	Microcircuits	Linear digital to analogue converter
08	69	Microcircuits	Linear other functions
08	80	Microcircuits	Logic families
08	95	Microcircuits	MMIC
08	99	Microcircuits	Miscellaneous
09	01	Relays	Non-latching
09	02	Relays	Latching
10	01	Resistors	Metal oxide
10	02	Resistors	Wire-wound precision - including surface mount
10	03	Resistors	Wire-wound chassis mounted
10	04	Resistors	Variable trimmers
10	05	Resistors	Composition
10	07	Resistors	Shunt
10	08	Resistors	Metal film
10	09	Resistors	Chip - all
10	10	Resistors	Network - all
10	11	Resistors	Heaters, flexible
11	01	Thermistors	Temperature compensating
11	02	Thermistors	Temperature measuring
11	03	Thermistors	Temperature sensor
12	01	Transistors	Low power, NPN - < 2 W
12	02	Transistors	Low power, PNP - < 2 W
12	03	Transistors	High power, NPN - > 2 W
12	04	Transistors	High power, PNP - > 2 W
12	05	Transistors	FET N channel
12	06	Transistors	FET P channel
12	09	Transistors	Switching
12	10	Transistors	RF/microwave NPN low power/low noise
12	12	Transistors	RF/microwave FET N-channel/P-channel
12	13	Transistors	RF/microwave bipolar power
12	14	Transistors	RF/microwave FET power - Si
12	15	Transistors	Microwave power - GaAs
12	16	Transistors	Microwave low noise - GaAs
13	01	Wires and cables	Low frequency
13	02	Wires and cables	Coaxial
13	03	Wires and cables	Fibre optic
14	01	Transformers	Power
16	01	Switches	Standard DC/AC power toggle
18	01	Opto-electronics	Opto-coupler
18	02	Opto-electronics	LED
18	03	Opto-electronics	Phototransistor
18	04	Opto-electronics	Photo diode/sensor
18	05	Opto-electronics	Laser diode
27	01	Fibreoptic components	Fibre/cable
30	01	RF passive devices	Coaxial couplers
30	07	RF passive devices	Isolator/circulator
30	09	RF passive devices	Coaxial power dividers
30	10	RF passive devices	Coaxial attenuators/loads
30	99	RF passive devices	Miscellaneous

ANNEX(informative)ESCC Exceptions

This annex contains the list of the ESCC detail specifications applicable at the time of publication and containing deviations to general derating requirements of this standard.

There are presently no ESCC Detail Specifications recording derating deviations to ECSS-Q-ST-30-11.

Bibliography

ECSS-S-ST-00

ECSS system - Description and implementation and general requirements

Derating - EEE components
Change log
Introduction
ANNEX(informative)Family and group codes
ANNEX(informative)ESCC Exceptions
Bibliography