Failure Mechanism and Testing of PCB Pad Cratering
作者: Shangguan, Dongkai ; Cai, Miao ; Xie, Dongji ; Geiger, David ; Wu, Boyi ; Martin, Ivan
Pad cratering of printed circuit board (PCB) is becoming a prevailing issue encountered in the PCB assemblies which is accelerated when switching to leadfree process. These units with pad cratering may not fail during functional test as and raise potential failure in the field. This paper uses both experimental and finite element analysis (FEA) approaches to understand the pad strength and pad stresses. An extensive mechanical test by pin pull tests are performed on PCB materials. Cohesive elements are employed to simulate the bonding at the interfaces of pad, laminate and fibers. The results from FEA show that the laminate cracking can be successfully simulated. The design variables such as traces and solder fillet impact are also critical for pad cratering.
2002-12-05·ELECTRONICS LETTERS
Semi-insulating buried heterostructure laser with PN fence
作者: White, J.K. ; Pakulski, G. ; Knight, G. ; Jones, T. ; Blaauw, C. ; Das, S.R.
The design, fabrication, and performance, of an Fe-doped InP semiinsulating buried heterostructure laser using a PN fence that prevents Zn and Fe interdiffusion is described.
2002-11-01·Journal of Optics A: Pure and Applied Optics
Flexible polymer waveguides for optical wire bonds
作者: Clayton, Richard ; Robinson, Jason ; Clark, Cynthia
Low-loss flexible polyimide waveguides have been fabricated and optoelectronic components have been successfully connected together using these waveguides.The waveguides were fabricated from com. available polyamic acid and heat cured to form polyimide.Low bulk material absorption of the core polymer was measured in the 1300-1600 nm range.A processing technique which produced buried core waveguides removable from a Si wafer was developed.Low (2 dB cm-1) fiber-to-fiber losses of flexible waveguides were measured.A novel optical wire bonding technique which removed flexible waveguides from a Si wafer and connected them to optoelectronic chip facets is successful.