Mil-PRF-38534 Class K

The MIL-PRF-38534 Class K electrical test standard describes the evaluation criteria for semiconductor bare die used to assemble space-grade hybrid and MCM (Multi-Chip-Module) circuits. The standard originates in the USA and is globally recognized; as such the standard is often considered a baseline for space application customers to specify their component qualification needs. For this reason, the standard may also be relevant when considering other applications where extremely high reliability is required for example such as use in nuclear power control or high temperature industrial. There are multiple pseudonyms used in the industry for this test process including “Class K Element Evaluation (EE)”, “Class K Lot Qualification” or “Class K Lot Acceptance Test (LAT)”.

At Reltronix the test flow is applied in exact accordance with MIL-PRF-38534 Class K.  The product is a comprehensive datapack containing:

  • Process Flow Traveller
  • Mechanical Test Results
  • Electrical Test Results at room temperature plus hot and cold datasheet limits


Scanning Electron Microscopy (SEM) Analysis

  • Certificate of Conformance.


The datapack is provided both physically and electrically to the customer and includes all the sample devices assembled and tested for traceability and long term retention.

Reltronix datapack

Our certificate of conformance certifies we have tested the candidate devices against this standard irrespective of pass or fail. Where devices meet the standard, a certified level of quality assurance is provided. Where they do not meet the standard, the test data pack is still provided with detailed electrical information available for customer consideration and analysis.
The material coverage of the Class K electrical test flow is restricted to samples taken from a single wafer. No assumption of production homogeneity within a wafer lot is made, therefore if production material is sourced from multiple wafers, even if from the same production lot, then a Class K qualification is required for material for each wafer used. Class K qualification takes significantly longer than Class H qualification, due to the higher number of processes involved and also mutlple burn-in elements which prove out device durability and life at temperature extremes. The Class K flow is often used as the baseline template for custom test regimes because by either extending or reducing elements of the flow or by adjusting sample sizes run can provide an application specific test regime.
For applications which require reliability assurance but don’t require life testing, consider MIL-STD-385354 Class H.

MIL-PRF-38534 Class K process flow:


Sample Selection

Single diffusion – Single Wafer only
Sample size – 20 PCS (5 destruct)


Pre-Sample Assembly

Die Visual Inspection – MIL-STD-750/TM2072, MIL-STD-750/TM2071, MIL-STD-883/TM2010A


Sample Assembly

Die Attach – MIL-STD-883/TM2010
Die Attach Inspection – MIL-STD-883/TM2010
Wire bond – Internal spec
Pre-Cap inspection – MIL-STD-883/TM2010
Internal Die Visual – MIL-STD-883/TM2010A, MIL-STD-750/TM2072, MIL-STD-75/TM2073
Package seal – MIL-STD-883/TM1014
Seal Inspection – MIL-STD-883/TM2009
Sample coding – Internal spec


Sample Testing

Stability Bake – MIL-STD-883/TM1008
Temperature Cycle – MIL-STD-883/TM1010
Centrifuge – MIL-STD-883/TM2001
Interim Electrical Test @ 25°C – In accordance with device specification
Interim Electrical Test @ 125°C – In accordance with device specification
Interim Electrical Test @ -55°C – In accordance with device specification
120 hours burn-in @ 150°C – In accordance with device specification
Post 120-hour Electrical Test @ 25°C – In accordance with device specification
Post 120-hour Electrical Test @ 125°C – In accordance with device specification
Post 120-hour Electrical Test @ -55°C – In accordance with device specification
Steady State Life Test @ 150°C – MIL-STD-883/TM1005
Life burn-in 240 hours – MIL-STD-883/TM1015
Final Electrical Test @ 25°C – In accordance with device specification
Final Electrical Test @ 125°C – In accordance with device specification
Final Electrical Test @ -55°C – In accordance with device specification


Mechanical Testing

Die Shear Test – MIL-STD-883/TM2019
Wire bond integrity – MIL-STD-883/TM2011
SEM Inspection – Scanning Electron Microscopy – MIL-STD-883/TM2018


Outgoing Die Release*

*If we are supplying production bare die via our sister company Die Devices the datapack is typically supplied in tandem.

We can perform Class K qualification on a broad range of semiconductor devices, please check out our test capabilities for further information.
If you need silicon processing prior to the Class H qualification step, such as wafer probing, wafer dicing or pick and placing, these options are also available.

Sales & Support

Environmental Testing

We offer a selection of in-house environmental tests, such as centrifuge acceleration, life burn-in, stabilization bake and thermal shock temperature cycling.

Mechanical Testing

We offer a comprehensive selection of mechanical tests, from ball shear, die shear, wire bond pull to SEM inspection.

thermal cycle machine display
Temperature Cycle
thermal cycle machine in operation
Temperature Cycle