Title :
A novel epoxy flux on solder paste for assembling thermally warped POP
Author :
Ming Hu ; Lee Kresge ; Ning-Cheng Lee
Abstract :
A novel epoxy flux EF-A was developed with good compatibility with no-clean solder pastes, and imparts high reliability for BGA assembly at a low cost. This compatibility with solder pastes is achieved by a well-engineered miscibility between epoxy and no-clean solder paste flux systems, and is further assured with the introduction of a venting channel. The compatibility enables a single bonding step for BGAs or CSPs, which exhibit high thermal warpage, to form a high-reliability assembly. Requirements in drop test, thermal cycling test (TCT), and SIR are all met by this epoxy flux, EF-A. The high viscosity stability at ambient temperature is another critical element in building a robust and user-friendly epoxy flux system. EF-A can be deposited with dipping, dispensing, and jetting. Its 75°C Tg facilitates good reworkability and minimizes the adverse impact of unfilled underfill material on TCT of BGA assemblies.
Keywords :
ball grid arrays; chip scale packaging; resins; semiconductor device reliability; semiconductor device testing; solders; viscosity; BGA assembly; CSP; EF-A; POP assembly; SIR; TCT; ball grid array; chip scale package; drop test; epoxy flux; high-reliability assembly; no-clean solder paste flux system; package on package assembly; thermal cycling test; thermal warpage; venting channel; viscosity stability; Assembly; Curing; Joints; Liquids; Polymers; Powders; Reliability; BGA assembly; Epoxy flux; SMT; TCT; drop test; flux; reliability; solder paste; thermal cycling test;
Conference_Titel :
Electronics Manufacturing Technology Conference (IEMT), 2014 IEEE 36th International
DOI :
10.1109/IEMT.2014.7123074
