Electronics Forum | Mon Jul 29 18:59:08 EDT 2002 | davef
Stand-ups are a common problem with 0402. Search the fine SMTnet Archives to get started.
Electronics Forum | Wed Jul 31 17:35:16 EDT 2002 | davef
* Finally, when soldered by hand, do the problem pads take solder? Yes, the XRF analysis will be interesting.
Industry News | 2019-11-05 22:07:01.0
Tenting a via refers to covering via with soldermask to enclose or skin over the opening. A via is a hole drilled into the PCB that allows multiple layers on the PCB to be connected to each other. A non tented via is just a via that is not covered with the soldermask layer. Leaving these vias exposed or covered has pros and cons depending on the your design and manufacturing requirements.
Technical Library | 2019-06-07 14:49:54.0
ACI Technologies was contacted in regards to poor solder joint reliability. The customer submitted an assembly that was exhibiting intermittent opens at multiple locations on a ball grid array (BGA) component. The assembly’s functionality did not survive international shipping, essentially shock and vibration failures, immediately making the quality of the solder joints suspect. The customer was asked about the contract manufacturer and the reflow oven profile as well as the solder paste and surface finish used. The ACI engineering staff evaluated the contract manufacturer’s technique and determined that they were competent in the methods they used for placing thermocouples in the proper locations and developing the reflow oven profile. The surface finish was unusual, but not unheard of, in that it was hard gold over hard nickel, rather than electroless nickel immersion gold (ENIG). The customer was able to supply boundary scan testing data which showed a diagonal row of troublesome BGA pins.
Surface Mount Technology Association (SMTA) | https://www.smta.org/education/presentations/presentations.cfm
. Three surface finishes including OSP, ImAg, and ENIG are considered. The test vehicle consists of 15mm and 6mm Ball Grid Array (BGA) components. The assembled test boards were isothermally aged at 125oC for 12 months, which are then thermally cycled between -40oC to
Heller Industries Inc. | https://hellerindustries.com/wp-content/uploads/2022/06/Optimizing-Reflowed-Solder-TIM-sTIMs-Processes-for-Emerging-Heterogeneous.pdf
. The key factors preventing the bubble bursting are: Poor wetting on adjacent solderable surfaces, trapping the void against the surface Dishing (concavity) of upper surface Trapping by rough surface intermetallics, or by the solid content of a solder
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