Solder Immersion Process of Ceramic Column Grid Array Package Assembly for Space Applications

Abstract

Ceramic column grid array (CCGA) packages are progressively being utilized for logic and microprocessor functionalities requiring very high-density interconnections. These packages offer various advantages, such as high reliability, good thermal and electrical performance, and reduced size and weight, due to which the use of these packages in space applications is becoming more and more popular. Assembly of such packages is always challenging for assembly and quality assurance engineers due to its post assembly inspection and rework limitations. These packages are usually assembled using the standard surface-mount technology (SMT) assembly processes involving solder paste printing on printed circuit boards (PCBs), component placement, and reflow soldering. An innovative tweak to the SMT process named solder immersion process (SImP) for assembly of CCGA is invented, where the solder paste is applied on the columns of the CCGA packages replacing the conventional solder paste printing/dispensing. SImP is useful for prototyping and reworkability and results in substantial improvement of the solder joint quality. This article explains the SImP in detail, test vehicle preparation, quality evaluation and subsequent accelerated thermal cycling test results, its applications, and advantages in the field of prototyping and reworkability.