Advantage and challenge of coreless flip-chip BGA

Abstract

This paper described the shadow moiré measurement of bare flip chip coreless and standard (3/2/3) BGA substrate to inspect the change of each thermal history (0hr, after pre-baking, IR-reflow), the warpage increased significantly on IR reflow peak temperature and largest warpage located around the C4 area of coreless FCBGA substrate and standard FCBGA substrate change was not obvious. Electrical performance was simulated by Ansoft Q3D and HFSS software, the coreless flip chip BGA substrate showed higher insertion loss and lower return loss than standard (3/2/3) flip chip BGA substrate. Bump stress, die stress and Cu trace stress of substrate were simulated by FEA (Finite Element Analysis) method, the results indicate that coreless flip chip BGA performs lower die stress and bump stress and higher trace stress than standard (3/2/3) flip-chip BGA. Furthermore, this study also found out the optimal assembly process condition. For the reliability evaluation, all of packages were subjected to pre-condition of JEDEC Level 3, TCT (Temperature Cycling Test), HTSL (High temperature Storage Life) and HAST (High accelerated stress test) and the results showed passed.

Study on the Nonlinear Characteristic Effects of Dielectric on Warpage of Flip Chip BGA Substrate

“…Despite many technical challenges, ultra thin or coreless substrate has been studied for its capabilities for high-end flip-chip BGA (Ball Grid Array) applications. 4,5) Robert Sung compares the coreless (6 layers or 4 layers) and the standard (6 layers, 0.8 mm core layer) flip-chip substrate from the viewpoint of electrical performance.…”

New dummy design and stiffener on warpage reduction in Ball Grid Array Printed Circuit Board

“…Accordingly, the electrical properties between the chip and the PCB must be optimized if new technologies are to be implemented successfully. Thin core or coreless PCB has been developed to meet both high density interconnection and high electrical performance requirements for the Flip Chip Ball Grid Array (FCBGA) PCB [1,2]. Nevertheless, warpage is one of most difficult issues to develop thin core or coreless PCBs.…”

Numerical Analysis on the Design Variables and Thickness Deviation Effects on Warpage of Substrate for FCCSP

“…[8][9] 특히, 최근 FCCSP 기판의 코어두께가 감소하거나 코어가 없는 코어리스 구조가 확대되면서 기판의 warpage 가 증가하고 있으며 이러한 warpage는 패키지의 신뢰성불 량과 생산성 하락에 근원적 원인이 되고 있다. [10][11] FCCSP용 Table 2~Table 4와 같은 기판의 설계인자 조건 참고문헌…”