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Board Level Reliability Testing: Current Challenges

Posted by DfR Solutions on Mar 7, 2019 1:16:29 PM

As the smartphone market has stagnated, semiconductor manufacturers have started to pivot their focus to automotive electronics to find the next large volume growth opportunity. This adjustment is for good reason: while smartphone volumes have not changed in over three years, automotive electronics will be the fastest growing market for integrated circuits until at least 2021.

To be successful in the competitive landscape that is automotive electronics, semiconductor manufacturers must account for differences in how automotive OEMs and their suppliers qualify integrated circuits compared to consumer products. While the differences are numerous, a key factor is the critical importance of board level reliability testing.

WHAT IS BLRT?

BLRT is the process of evaluating the robustness of the semiconductor package once the device is soldered to the printed circuit board (PCB). The primary focus of BLRT has been on the reliability of the solder joint, but increasingly there are other aspects of the semiconductor package which can be susceptible to failure only after assembly. BLR, while relatively common now, was a deviation from common semiconductor qualification practices. Legacy requirements, starting with the military standard MIL-STD-883, mostly focused on the robustness of the stand-alone device. All testing (temp cycling, mechanical shock, humidity, etc.) was performed without permanently attaching the device to anything. The semiconductor industry started to consider performing BLRT as part of a standard qualification process only after the introduction of BGA and QFN packaging and several high-profile solder failures (cyclic bending failure under cell phone keypads was the most prominent).

Download our free whitepaper here on 6 Steps to Successful Board Level Reliability Testing to learn more about designing relevant board level reliability testing plans.

However, even to this day, the process of BLRT is poorly standardized within the electronics industry. There is no better example than the qualification documents created by the Automotive Electronics Council (AEC). The AEC is effectively considered the component standards body for the automotive industry and therefore develops templates for qualifying integrated circuits (Q100), discretes (Q101), passives (Q200), and multi-chip modules (Q104). However, the first three documents (Q100, Q101, Q200) make no mention of any kind of BLRT to qualify devices for automotive applications. Only Q104 mentions BLR and, even then, provides limited guidance as to requirements for test parameters and duration. The typical results are costly surprises for automotive Tier 1 manufacturers when they perform their own qualifications tests at board or system-level.

HOW ARE ORGANIZATIONS CURRENTLY PERFORMING BLRT?

Despite the lack of standardization, there are still industry documents that can be helpful in developing individual BLR tests. The most overarching document is JEDEC JEP150 Stress-Test-Driven Qualification of and Failure Mechanisms Associated with Assembled Solid-State Surface Mount Components. Initially released in 2005 and then updated in 2013, the document provides a table of potential BLR tests and helpful standards for developing these tests. A pared down list of recommended BLR tests (some tests listed are considered optional) is shown below:

  • Assembly to the board: Per JESD22A113
  • Temperature/Humidity/Bias (THB): No test standard provided
  • Temperature/Humidity: No test standard provided
  • Temperature Cycling: Per JESD22A104, Condition J
  • Power Temperature Cycling: Per JESD22A105
  • Drop Testing: Per JESD22B110, Condition A
  • Vibration, Harmonic: Per JESD22B103, Condition 1
  • Bending, Monotonic and Cyclic: Per IPC/JEDEC 9702

As discussed above, AEC Q104 also provides a list of recommended BLR tests (Test Group H), but the number of tests is smaller than those provided in JEP150. The BLR tests included in Q104 are:

  • Temperature Cycling: Per IPC-9701
  • Low Temperature Storage Life: Per JESD22A119
  • Start Up and Temperature Steps: Per ISO 16750-4
  • Drop Testing: Per JESD22B111, Condition B

Other examples of industry standards that describe BLR tests include IPC-9703 Mechanical Shock, IPC-9707 Spherical Bend, and JESD22B113 Cyclic Bend. All these standards leave out, to some degree, clear guidance regarding test coupon design, test conditions, test duration, and definition of failures. This vagueness can be considered an advantage, providing flexibility to the semiconductor manufacturer in helping them pass any or all BLRT. Conversely, it can be considered a disadvantage when a customer makes certain assumptions regarding BLRT that are not valid.

With no universal standard for BLRT, the result is confusion, delay, and dissatisfaction up and down the supply chain.

Download our free whitepaper here on 6 Steps to Successful Board Level Reliability Testing to learn more about designing relevant board level reliability testing plans.

CONCLUSION

Semiconductor manufacturers are in a bind: while there is accepted documentation to serve as a guide, there is a gap in the requisite qualifications between consumer products and automotive suppliers. For semiconductor manufacturers entering the automotive environment, this lack of universal qualifications standards often leads to inconsistent reliability expectations. The established standards are not wrong, rather they do not address the complex and abundant automotive applications of today. DfR Solutions has consistently found that the most efficient solution is to establish a robust and thorough BLR testing plan that is uniquely designed for a specific manufacturer and validated by a broad range of industry experiences. 

Contact a DfR Solutions representative today to learn more about the turnkey implementation and execution of a BLRT plan in which manufacturers can have a high degree of confidence.

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Topics: electronics failure, electronics test design, reliability testing, Reliability Physics, Standards Based Testing

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