The study of plastic package cracking induced by the moisture/solder reflow process

2003 ◽  
Author(s):  
H. Kitagawa ◽  
Y. Kido ◽  
K. Maeda ◽  
Y. Umeda ◽  
H. Sano ◽  
...  
Keyword(s):  
Reflow Process ◽  
Plastic Package ◽  
Solder Reflow

Thermoplastic Optical Polymers with Lead-Free Solder Reflow Resistance for HB-LED Packaging and Assembly

2010 ◽  
Vol 2010 (1) ◽  
pp. 000156-000163
Author(s):  
Weijun Zhou ◽  
Quan Yuan ◽  
Chris Li ◽  
Stephen F. Hahn ◽  
Kurt A. Koppi ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Dimensional Stability ◽  
Moisture Absorption ◽  
Lead Free ◽  
Lead Free Solder ◽  
Optical Polymers ◽  
Reflow Process ◽  
Short Period ◽  
Solder Reflow ◽  
Free Solder

A new class of thermoplastic optical polymers made by substantially fully hydrogenating block copolymers of styrene and butadiene, known as cyclic block copolymers (CBCs), were recently discovered to exhibit lead-free solder reflow resistance with peak reflow temperature up to 260°C. This kind of behavior is uncommon for traditional thermoplastic polymers. The block copolymer design and the resulting nanostructured morphology lead to strong elastic and soft solid material characteristics for CBC, which may explain why CBCs can maintain good dimensional stability at high temperatures (i.e., above its glass transition temperature, Tg) for a short period of time such as in a solder reflow process. This hypothesis was examined by computational fluid dynamics modeling on a molded CBC lens of LUXEON K2 LED package configuration. When the CBC lens is subjected to a simulated solder reflow process, the change in physical dimension due to thermal expansion and gravity effects is predicted to be negligible. However, the residual stress in the molded lens may play a profound role on its dimensional stability. There exists a critical stress value below which no observable deformation is predicted for the CBC lens. With excellent optical transparency and good long term optical stability, low moisture absorption, and good injection moldability, CBCs is a promising class of materials for LED packaging that contributes to improved LED manufacturing economics.

scholarly journals Design for Plastic Packages of LSI Chips to Prevent Cracking during Solder Reflow Process.

2001 ◽  
Vol 4 (1) ◽  
pp. 47-55
Author(s):  
Toru IKEDA ◽  
Yuya UENO ◽  
Noriyuki MIYAZAKI ◽  
Nobutaka ITO
Keyword(s):  
Reflow Process ◽  
Plastic Packages ◽  
Solder Reflow

Sequential Reflow-Process Optimization to Reduce Die-Attach Solder Voids

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Youmin Yu ◽  
Victor Chiriac ◽  
Yingwei Jiang ◽  
Zhijie Wang
Keyword(s):  
Heat Transfer ◽  
Theoretical Prediction ◽  
Integrated Circuit ◽  
Sequential Optimization ◽  
Solder Paste ◽  
Lead Frame ◽  
Reflow Process ◽  
Sequential Method ◽  
Die Attach ◽  
Solder Reflow

Solder voids are detrimental to the thermal, mechanical, and reliability performance of integrated circuit (IC) packages and must be controlled within certain specifications. A sequential method of optimizing solder-reflow process to reduce die-attach solder voids in power quad flat no-lead (QFN) packages is presented. The sequential optimization consists, in turn, of theoretical prediction, heat transfer comparison, and experimental validation. First, the theoretical prediction uses calculations to find the optimal pause location and time for a lead frame strip (with dies bonded to it by solder paste) to receive uniform heat transfer during the solder-reflow stage. Next, reflow profiles at different locations on the lead frame strip are measured. Heat transfer during the reflow stage at these locations is calculated from the measured reflow profiles and is compared to each other to confirm the theoretical prediction. Finally, only a minimal number of actual trials are conducted to verify the predicted and confirmed optimal process. Since the theoretical prediction and heat transfer comparison screens out most of the unnecessary trials which must be conducted in common design of experiment (DoE) and trial-and-error methods, the sequential optimization method saves significant time and cost.

An Investigation into Moisture-Induced Cracking in Plastic Packages Using Thermal Analysis Techniques

1996 ◽  
Author(s):  
S. Chew
Keyword(s):  
Thermal Analysis ◽  
Degree Of Polymerization ◽  
Analysis Techniques ◽  
Design Changes ◽  
Plastic Package ◽  
Solder Reflow ◽  
The Difference ◽  
Precautionary Measures ◽  
Thermal Analysis Techniques ◽  
And Storage

Abstract Pop-corn package cracking in thin quad flatpack packages (TQFP) during surface mount solder reflow can be minimized by adopting precautionary measures such as design changes, selection of new grades of epoxy mold compound (EMC) with lower affinity for moisture and lower expansivity, shipment and storage of epoxy mold compound under dry pack, as well as drying of plastic package prior to solder reflow. This paper investigates, using thermal analysis techniques, the cause of pop-corning phenomenon from pad-plastic interface in a particular batch of TQFPs despite the precautionary measures adopted. By comparing the difference in EMC properties between a control and reject batch of TQFP, this study suggest that ensuring optimum degree of polymerization or cure of the epoxy encapsulant can also assist in minimizing package delamination and pop-corn cracking.

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