Issued Date: 2018/4/11
Issued By: iST
Which standard, AEC-Q100 or ISO16750, should be employed for automotive tests by manufacturers of complex multichips like MCM and SIP?
Which specification should be adopted for automotive IC mounting and PCB solder joints Board Level Reliability Test (BLR)?
This year, problems that baffled IC design houses and Tier 1 automotive module manufacturers for a long time could be solved with an official answer! The AEC Q-104 MCM specification, recently released by the Automotive Electronics Council (AEC)-appointed Multichip Modules (MCM) committee, including Lattice, Intel, Infineon, Microchip, NXP, On Semiconductor and TI will eventually eliminate the problem of testing by IC or module specification for complex multichip types including MCM, System in Package (SIP), and Stacked chips. In addition, the AEC-Q104 is the first automotive industry specification of its kind to define Board Level Reliability Test (BLR).
In addition to the four existing specifications, AEC-Q100, AEC-Q101, AEC-Q102, and AEC-Q200, the AEC-Q series will have the new AEC-Q104 for automotive multichip module reliability test added as well.
- The automotive electronics industry performs car grade verification based on standards created by the Automotive Electronics Council (AEC), including AEC-Q100 (IC chips), AEC-Q101 (discrete components), AEC-Q200 (passive components).
- AEC-Q102 (discrete optoelectronic components) and AEC-Q104 (multichip modules) are two automotive electronics specifications that have been released recently.
- In spite of being tougher than its consumer IC peers, the AEC test criteria are JEDEC or MIL-STD based along with additional specification including electromechanical compatibility (EMC) for example.
Please read the following six differences between AEC-Q104 and AEC-Q100 to get familiar with the AEC-Q104 in no time.
The AEC-Q104 specification comes with eight categories identified by the letters “A” to “H”. One rule of thumb is that MCM products shall be subject to just 7 items of AEC-Q104 Group H tests as long as its components include passive components (resistors, capacitors, and inductors), diode discrete components, and ICs that passed the AEC-Q100, 101 or 200 tests before being assembled. These 7 test items cover 4 reliability tests (temperature cycle test (TCT), drop, low temperature storage life (LTSL), start up and temperature steps) and 3 failure inspection tests (X-ray, acoustic microscopy (AM), destructive physical (DPA)). On the contrary, if the components within MCM products have not passed the AEC-Q100, 101 or 200 tests first, the verification items shall be chosen from all 49 items out of the eight categories based on product application. This, in turn, suggests more verification items would be required.
Diagram (click to enlarge): test items contained in AEC-Q104 A-H (source: AEC-Q104 specification)
Extra sequential tests
AEC-Q100 test items may be tested in random sequence. This is not the case with AEC-Q104. To mimic the compound environment encountered by MCM in practical driving scenario the sequential tests are required and the qualification condition gets tougher. As an example: you have to test High Temp Operating Life (HTOL) successfully before proceeding with Thermal Shock (TS) but not vice versa.
Extra test items
The AEC-Q104 adds an “H” category for tests addressing MCM product. In addition, the tests of thermal shock and visual inspection for migration (VISM) are added addressing component level reliability.
Revise ESD electrostatic discharge test specification
Addressing internal complexity of MCM internal components some changes are introduced in the AEC-Q104 specification. Regarding ESD test items: the minimum requirements of the Human Body Model (HBM) are down to 1KV from 2KV defined in AEC-Q100; Regarding Charged-Device Model (CDM): the AEC-Q100 set the corner pin at 750V and the rest at 500V while AEC-Q104 sets all pins, regardless of the pin out position, to 500V (see Table 1 for details).
ESD測試 AEC-Q100 AEC-Q104 HBM 2KV 1KV CDM Corner Pin is 750V and all the rest are 500V Pin Out: 500V for all
Table 1: Difference in ESD tests defined in AEC-Q100 and Q104
Change in quantity of test samples
The AEC-Q100 sets test quantity samples at 77 pieces in each of 3 lots while the AEC-Q104 specification lowers this to 30 pieces in each of 3 lots due to high costs of MCM complex chips.
Define automotive BLR test items for the first time
The Board Level Reliability (BLR) is the most common global method to verify IC component solder joint reliability after being mounted on PCB. It has been a routine test item for hand-held devices; however, as more IC components are used in cars which increase the complexity of the automotive electronic system, the BLR has gradually become one of the important test items of automotive electronics.
Tier 1 module makers are making rising efforts in creating proprietary board level tests, including Bosch, Continental, and TRW. More strikingly, the AEC has also come up with the latest AEC-Q104 qualification to clearly define the test items of BLR. Although the AEC-Q104 covers only Temperature Cycle Test (TCT), Drop Test, Low Temperature Storage Life (LTSL) and Start up & Temperature Steps (STEP), etc, and has not been completely close to the specification of Tier 1 makers; AEC-Q104 is treated as a big step in the BLR general standard.
AEC-Q104 BLR test items description
- Reference standards of TCT, Drop, LTSL come the same as those for consumer electronics and without special requirements.
- Start up and temperature steps: adopts reliability standards set forth in ISO 16750 automotive modules by keeping test samples at discrete temperature levels for function tests.
The iST has been accessed by multiple international chip makers for use in testing after the AEC-Q104 specification was released. This suggests the specification is quite important! However, the AEC-Q104 specification is aimed at global automotive IC design houses, and is less likely to meet requirements of vehicle manufacturers and Tier 1 automotive module makers. AEC-Q104 is the entry ticket for suppliers trying to step into the automotive industry. To take a hold in the automotive supply chain the MUST is to comply with the custom specifications of individual car makers. For more details, please contact Ms. Sherry Wu at +886-3-579-9909 Ext. 6403 or email her at TID@istgroup.com.