Technical Library | 2012-12-26 14:18:24.0
Passive components including resistors, capacitors, inductors, and circuit-protection devices compose the highest percentage of all devices that are populated on today’s PCB assemblies. However, the successful isolation and testing of these components during ICT is perhaps the most challenging and the least understood of all modern-day validation practices.
Technical Library | 2020-12-10 15:49:40.0
Electronic assemblies should have longer and longer service life. Today there are partially demanded 20 years of functional capability for electronics for automotive application. On the other hand, smaller components, such as resistors of size 0201, are able to endure an increasing number of thermal cycles until fail of solder joints, so these are tested sometimes up to 4000 cycles. But testing until the end of life is essential for the determination of failure rates and the prognosis of reliability. Such tests require a lot of time, but this is often not available in developing of new modules. A further acceleration by higher cycle temperatures is usually not possible, because the materials are already operated at the upper limit of the load. However, the duration can be shortened by the use of liquids for passive tests, which allow faster temperature changes and shorter dwell times because of better heat transfer compared to air. The question is whether such tests lead to comparable results and what failure mechanisms are becoming effective. The same goes for active temperature cycles, in which the components itself are heated from inside and the substrate remains comparatively cold. This paper describes the various accelerated temperature cycling tests, compares and evaluates the related degradation of solder joints.
Technical Library | 2016-01-12 11:01:25.0
More and more Land Grid Array (LGA) components are being used in electronic devices such as smartphones, tablets and computers. In order to enhance LGA mechanical strength and reliability, capillary flow underfill is used to improve reliability. However, due to the small gap, it is difficult for capillary underfill to flow into the LGA at SMT level. Due to cost considerations, there are usually no pre-heating underfill or cleaning flux residue processes at the SMT assembly line. YINCAE solder joint encapsulant SMT256 has been successfully used with solder paste for LGA assembly. Solder joint encapsulant is used in in-line LGA soldering process with enhanced reliability. It eliminates the underfilling process and provides excellent reworkability. The shear st rength of solder joint is stronger than that of underfilled components. The thermal cycling performance using solder joint encapsulant is much better than that using underfill. Bottom IC of POP has been studied for further understanding of LGA assembly process parameters. All details such as assembly process, drop test and thermal cycling test will be discussed in this paper.
Technical Library | 2021-01-28 01:55:00.0
Printed circuit board surface finishes are a topic of constant discussion as environmental influences, such as the Restriction of Hazardous Substances (RoHS) Directive or technology challenges, such as flip chip and 01005 passive components, initiate technology changes. These factors drive the need for greater control of processing characteristics like coplanarity and solderability, which influence the selection of surface finishes and impact costs as well as process robustness and integrity. The ideal printed circuit board finish would have good solderability, long shelf life, ease of fabrication/processing, robust environmental performance and provide dual soldering/wirebonding capabilities; unfortunately no single industry surface finish possesses all of these traits. The selection of a printed circuit board surface finish is ultimately a series of compromises for a given application.
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