ECSS-Q-70-38A Rev.1 – High-reliability soldering for surface-mount and mixed technology (5 December 2007)

This Standard has been cancelled and replaced by ECSS-Q-ST-70-38C (31 July 2008).


This Standard defines the technical requirements and quality assurance provisions for the manufacture and verification of high-reliability electronic circuits based on surface mounted device (SMD) and mixed technology.

The Standard defines acceptance and rejection criteria for high-reliability manufacture of surface-mount andmixed-technology circuit assemblies intended to withstanding normal terrestrial conditions and the vibrational g-loads and environment imposed by space flight.

The proper tools, correct materials, design and workmanship are covered by this document. Workmanship standards are included to permit discrimination between proper and improper work.

The assembly of leaded devices to through-hole terminations and general soldering principles are covered in ECSS-Q-70-08.

Requirements related to printed circuit boards are contained in ECSS-Q-70-10 and ECSS-Q-70-11. The substrates covered by this document are divided into five classes in accordance with their average X and Y coefficient of thermal expansion (CTE).

The mounting and supporting of components, terminals and conductors prescribed herein applies to assemblies designed to operate within the temperature limits of -55 ºC to +85 ºC.

For temperatures outside this normal range, special design, verification and qualification testing is performed to ensure the necessary environmental survival capability.

Special thermal heat sinks are applied to devices having high thermal dissipation (e.g. junction temperatures of 110 ºC, power transistors) in order to ensure that solder joints do not exceed 85 ºC.

Verification of SMD assembly processes is made on test vehicles (surface mount verification samples). Temperature cycling ensures the operational lifetime for spacecraft. However, mechanical testing only indicates SMD reliability as it is unlikely that the test vehicle represents every flight configuration.

Examples of the method for achieving SMD verification approval and guidelines for the soldering of area array devices are given in the Annexes.

This Standard does not cover the qualification and acceptance of the EQM and FM equipment with surface-mount and mixed-technology.

The qualification and acceptance tests of equipment manufactured in accordance with this Standard are covered by ECSS-E-10-03.


This standard cancels and replaces ECSS-Q-70-38A (26 October 2007).