AEC-Q200 and Ceramic PCBs: How to Qualify an Automotive Substrate

AEC-Q200 does not apply to a bare ceramic PCB. It is the Automotive Electronics Council’s stress-test qualification for passive components such as capacitors, resistors and inductors, and the council states there is no AEC-Q200 certification at all. An automotive ceramic substrate is qualified instead against a test plan agreed with the customer: usually temperature cycling to a stated range (for example −55 to +150 °C with 15-minute dwells), inspection for cracks and copper delamination, and production approval through PPAP, from a supplier certified to IATF 16949.

Does AEC-Q200 Apply to a Ceramic PCB?

No. AEC-Q200 Revision E sets stress tests for passive electrical components, and a ceramic capacitor is in scope because it is a passive component, not because it is ceramic (AEC-Q200 Rev E, 2023). An unpopulated alumina or aluminum nitride substrate is not a component in that sense.

The same document says there is no AEC-Q200 certification and no certifying board: the component supplier runs the qualification tests and gives the data to its customer. So a quote or datasheet that calls a ceramic board “AEC-Q200 certified” is describing something the standard does not offer. What a substrate supplier can legitimately say is that it ran a test using a method borrowed from AEC-Q200 or another standard, under conditions it states.

Where AEC-Q200 does matter is the bill of materials: the capacitors, resistors and inductors you solder onto the ceramic board should be AEC-Q200 qualified parts from their makers.

Which Standards Apply to an Automotive Ceramic Substrate?

Several, each for a different object. Use them together rather than looking for one that covers everything:

IEC 60068-2-14 was revised in 2023 and now sets out specimen temperature, severity, tolerances and reporting for the Na (rapid change) and Nb (specified rate) tests (IEC 60068-2-14:2023). It tells you how to run the test, but the temperature limits, dwell, number of cycles and pass criteria come from your mission profile and your customer’s specification.

For inverter and onboard-charger work, AQG 324 is the document most module customers reference. It qualifies the module design and assembly, so the substrate’s own test results are an input to that qualification rather than a replacement for it.

Which Ceramic and Metallization Survive Thermal Cycling Best?

Strong, low-expansion ceramics with thick copper bonded by a tough joint last longest; plain aluminum nitride with direct-bonded copper (DBC) cracks first. In one published comparison, Rogers cycled DBC substrates from −55 to +150 °C with 15-minute dwells, using 0.3 mm copper on both sides and 0.32 mm ceramic (0.63 mm for AlN): AlN passed more than 700 cycles, Al2O3 more than 1,500, and its zirconia-toughened HPS alumina more than 3,000 (Rogers curamik Endurance, 2021). The same document warns that a customer’s own copper layout will give different numbers.

Silicon nitride is usually paired with active-metal-brazed (AMB) copper where cycling is most severe, because it combines the lowest expansion of the three with much higher strength than alumina or AlN. Cracking is driven by the mismatch between copper (about 17 ppm/K) and the ceramic, set against the ceramic’s strength:

Data: Rogers curamik datasheet (20 °C; CTE 20–300 °C) and MARUWA material data (25 °C; CTE 40–400 °C).

Rogers also notes that bonding copper raises the substrate’s effective CTE by 5% to 60%, depending on copper thickness, so thicker copper for current capacity also raises cycling stress. For a high-current traction inverter, that usually points to Si3N4 AMB; for an LED or sensor board with modest power swings, alumina may be enough. Our comparison of AMB and DBC substrates goes into the process differences.

What Should a Thermal Cycling Test Plan Specify?

Every condition that changes the result, written before samples are built. A cycle count without its temperature history cannot be compared with another report.

The example entries are illustrations; take the actual limits from the mission profile and the customer’s specification. Two points are easy to miss. First, chamber cycling, liquid thermal shock and powered cycling stress the substrate differently, so name the one the customer asked for. Second, record the before-and-after measurements under the same conditions; an insulation reading taken at a different voltage or temperature after cycling proves nothing.

Scanning acoustic microscopy finds copper-to-ceramic delamination without cutting the part, and cross-sections at the copper edges confirm what it shows. Plan where sections will be cut, because copper edges and corners are where cracks start.

Which Samples and Coupons Represent the Production Part?

Samples built on the production process with the production copper pattern, or coupons that reproduce the feature being tested. A coupon is only representative of what it shares with the part.

• Copper edges and pattern: cracks start at copper edges, so a coupon with a large uniform pad will outlast a part with narrow tracks and sharp corners. Include the tightest copper geometry from the real design.
• Thickness: ceramic and copper thickness must match; Rogers’ DBC options, for example, run from 0.127 to 0.5 mm copper, and AMB to 0.8 mm, and each combination behaves differently.
• Process route: a DBC coupon does not qualify an AMB part, and a part from another site is a different process.
• Finish and attach: if the module will be sintered or soldered to a baseplate, a free-standing substrate test leaves out that stress; say which one you tested.

Plan coupon positions and test access during the DFM review, before the panel and sample quantity are fixed.

What Is PPAP Level 3 and What Should It Include?

PPAP Level 3 is the default submission level in the AIAG PPAP manual: a Part Submission Warrant with product samples and complete supporting data sent to the customer (AIAG PPAP). The five levels are:

A full PPAP has 18 elements, among them the design record, process flow, PFMEA, control plan, measurement system analysis, dimensional results, material and performance test results and initial process studies. For a ceramic substrate, the useful content in “material and performance test results” is the ceramic datasheet and lot certificate, peel or adhesion results, the thermal cycling report for the representative build, and dimensional results for flatness, outline and copper features.

PPAP proves the production process makes parts that meet the design record. It does not decide which tests the design record should call for; that comes from the test plan above.

How Should You Review a Supplier’s Qualification Evidence?

By matching each requirement to a report on the same construction. Build a short index: requirement, report number, tested part revision, result and any deviation. Then check four things.

1. Construction match: ceramic grade, copper thickness, pattern revision, finish and production site in the report match your part.
2. Conditions: the test ran at your temperature limits and dwell, not a gentler profile.
3. Failure criteria: the report states how failure was judged, and the criteria are yours.
4. Change control: the supplier will notify you before changing ceramic source, bonding process or site, and you have agreed which changes need requalification.

Older reports and family data can be valid evidence if the construction matches; a recent report on a different build is not. Our questions for evaluating a ceramic PCB manufacturer cover the supplier side in more detail.

How Can We Help?

QueenEMS is certified to IATF 16949 as well as ISO 9001 and ISO 14001, and makes ceramic substrates in alumina, AlN and silicon nitride by DBC, DPC, AMB, HTCC or LTCC. For an automotive substrate, send the drawing, the copper thickness and pattern, the customer’s cycling profile and the required submission level; we will quote the build and state which tests and samples the quote includes. Materials, processes and certificates are listed on our ceramic PCB manufacturing page.

Conclusion

Qualify the substrate against a written test plan, keep AEC-Q200 for the components, and make sure every report describes the construction you are buying. Contact us with your drawing, ceramic and copper specification, cycling requirement and quantities.

FAQ

What is AEC-Q200? The Automotive Electronics Council’s stress-test qualification for passive components such as capacitors, resistors and inductors. The current base document is Revision E (2023).

Is there an AEC-Q200 certification? No. AEC-Q200 states there is no certification or certifying board; suppliers qualify their components and give the data to customers.

What is a PPAP Level 3? The default PPAP submission: a Part Submission Warrant with product samples and complete supporting data sent to the customer.

How many documents are in a PPAP? The AIAG manual lists 18 elements, although the customer decides which ones are submitted at each level.

How should ceramic substrates be evaluated for repeated thermal cycling? Test the production construction to the application’s temperature limits and dwell, and inspect for cracks and copper delamination at set intervals. Compare materials only from reports that used the same profile and copper thickness.