CSPs in portable devices pose new reliability requirements due to the high mechanical stresses experienced during their service lifetime. They offer robust interconnects and higher standoffs in comparison to flip chips. SrihariĪbstract: Chip Scale Packages (CSPs) are widely used in portable devices. Process Development And Mechanical Testing Of Csp UnderfillsĪuthors: Murtuza Rampurawala and K. X-ray analysis of the assemblies showed no cases of solder bridging, misregistration, or opens. All the components exhibited good solder joint formation on both Electroless Nickel Immersion Gold (ENIG) and Copper Organic Solderability Protection (Cu-OSP) coated Printed Circuit Board pads. No 'time-zero' failures were observed in any of the assemblies. The assemblies were characterized through x-ray analysis, cross-sectional analysis, and electrical testing. The assembly process, including stencil printing process, component placement, and reflow soldering, was optimized through experimentation. Four types of CSPs were assembled onto organic Printed Circuit Boards. All of these packages pass the electrical testing.Ĭsp Assembly Build At Manufacturers' Services Limited (Msl)Ībstract: The primary goal of this project was the implementation of a 'robust' CSP assembly process in a contract manufacturing environment. Package BD and BE show that no time-zero failure. Other cross-section shows that the solder mask partly covered the pad surface. One cross-section shows that the solder mask completely covered the pad surface. Two time-zero failures were observed on Package BH due to incomplete developed solder masks on several pads at site F1 and F3.

The cause of assembly defects was also investigated.

The assemblies were characterized through electrical testing, x-ray, and cross-sectional analysis to inspect the integrity of the solder joints. Packages BD and DE (stacked CSPs) and Package BH (extremely thin profile BGA) were assembled on Test Board 7-side F (TB7-F) using no-clean, eutectic Sn/Pb, Type 4 solder paste. This report discusses the assembly process and issues related with the assembly of these area array devices on different pad sizes and surface finishes. Assembly Build And Characterization Of Test Board 7-Side FĪbstract: Test Board 7-side F is a multilayered test vehicle with sites for the assembly of stacked Chip Scale Packages (CSPs) and thin profile Ball Grid Arrays (BGAs).

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