Environmental stress test for electronic products
The purpose of the environmental stress test mainly focuses on package assembly test quality of semiconductor components. The critical environment that affects package quality including: the temperature resistance level of the package structure, the temperature and humidity resistance of the package structure, the fatigue aging factors of the package structure, and the requirements related to storage and control.
The complexity of environmental stress test is more diversified and traditional single test has been gradually replaced by composite benefits due to environmental changes. Acid rain and exhaust gas derived from air pollution may cause corrosive speed mode under high temperature state, and it hasn’t been verified effectively by non-traditional concepts.
Environmental stress test
- Moisture Sensitive Level / MSL： For surface mount device (SMD) and non-hermetic (Non-hermetic) components or other ones that shall be proceeded SMT reflow process (Reflow) for verification. Ultrasonic scanning(SAT、SAM or CSAM)is applied to judge the delamination position and the delamination ratio, in order to establish the moisture sensitive level. As the moisture sensitive level is differentiated clearly, it enables to be employed for precondition test. The purpose of reliability pre-processing is to simulate the cycle process from component production, transportation to the customers’ mass production. The pre-treatment moisture absorption condition is based on the moisture sensitive level of the component and it is also the management reference for factory to use. Many reliability environmental stress tests need to be implemented before the pre-treatment is carried out.
- Temperature Cycling Test：Temperature cycling test is also called the foundation of reliability test, which is a very important one in reliability test. Apply the temperature cycling on components and create the effect of mismatched expansion coefficients in order to cause long-term fatigue of the component and result in failure. As for the component package, the problems that often occur including: Wiring drop off, structural delamination, metal fracture, soldering joint fatigue cracking and other phenomena are the simulation that is closest to practical usage.
- Temperature Humidity Bias Test：Apply the voltage to occur corrosion condition and form an accelerated mode chemical reaction under a high temperature and humid environment. Except for the static environmental test, the bias test is often applied to understand the risk of ion migration of metal materials inside the package and test the product corrosion resistance simultaneously. Owing to the long experiment period, a highly accelerated stress test (HAST) can be used instead. The difference is that the greater atmospheric pressure is generated will speed up the corrosion rate during the humidification process. According to JEDEC definition, a 96-hour HAST test can replace a 1000-hour high temperature and high humidity test (85 ° C / 85% RH).
- High / Low Temperature Storage Test：The purpose of this test is to verify the temperature tolerance and aging for the packaging material and accelerate the package material aging under continuous high or low temperature condition. Mechanical deformation is caused by expansion and contraction at extremely low temperature under low temperature test. Cracks is caused by embrittlement on the structure. Because the high and low temperature storage test is not in light of the package structure, but for the aging of the package material, therefore, the test can be performed without a pretreatment procedure.
- Thermal Resistance Test：Since most electronic products need to assemble, disassemble and repair in a hot environment, so they must withstand various heat-resistant simulations to ensure that the process is not damaged by thermal shock. The common methods include reflow, solder iron, hot air gun, solder dipping and other methods.
Package quality test
Besides environmental stress tests, there are a number of test items for the quality of component package:
- Solderability Test：Solderability test (Solderability Test): The purpose of the solderability test is to ensure the plating quality of the component pins or if the solder balls are contaminated. The standard experimental method uses the solder pot method, which must reach a coverage of more than 95%. For the BGA solder ball dip test, although there is still no regulatory standards, the SMT process simulation is adopted in industry to realized the practical usage.
- Wetting Balance Test：Wetting Balance Test: The purpose of the wetting balance test is to analyze the soldering controversy. The contact reaction speed between the component pin and tin can be estimated the potential risk of the component pin. The blind spot of the solderability test is also an effective way to verify expired materials.
- Pull / Shear Test：Pull / shear test: The tensile test is mainly aimed at the quality of the package and wire bonding process. The push / pull force value is collected for SPC calculation to determine its variation and continuous optimization through this test. Additionally, for BGA solder balls, solder ball thrust can be performed and refer to its value of AEC to determine whether they are qualified to ensure that the joint strength of the solder meets the standard.
- Pb-Free Test：Lead-free process test (Pb-Free Test): Lead-free process test is a broad definition. The lead-free process to introduce in electronic products has been about fifteen years, so it is quite mature now. In recent years, the lead-free process has been adopted in the automotive market and the demand for tin whiskers has been reopened. Therefore, the lead-free process has become a standard test project in the field of automotive products.
VESP Technology Corp. has recruited senior staffs who have many years of practical experience in semiconductor component reliability testing in industry. In order to provide customers with a better service platform, we have established dedicated personnel for services to provide experimental designs and overall plans.
Mr. Su / Hardware evaluation and integration engineering / 03-6669700 ext. 6261
Mrs. Huang / Project Management / 03-6669700 ext. 6265