- Irvine, California, United States
Electronic devices require a greater degree of functionality in smaller spaces. While this trend is rampant in handheld devices (mobile phones, tablets, MP3 players, etc.), the components, materials, and methods used there soon find... more
Electronic devices require a greater degree of functionality in smaller spaces. While this trend is rampant in handheld devices (mobile phones, tablets, MP3 players, etc.), the components, materials, and methods used there soon find there way into other applications. For many years underfill materials that have been used to increase the reliability of BGA and CSP packages on SMT boards have focused more on enhancing drop testing reliability versus enhancing thermal cycling performance. With the advent of smaller pitch wafer level chip scale devices (WLCSPs), the thermal cycling enhancement is becoming more critical. These consumer device applications also require that this increase in performance does not affect the other underfill attributes that have become more commonplace, such as: room temperature flow, reworkability, and drop-test improvement. These same performance characteristics can also lead to improved performance for CSP and WLCSP devices used in other applications beyond consumer devices as well.
This paper will describe the material properties that affect these various aspects of underfill performance and the challenges around the performance of such materials.
This paper will describe the material properties that affect these various aspects of underfill performance and the challenges around the performance of such materials.
Research Interests:
Reflow profile has significant impact on solder joint performance because it influences wetting and microstructure of the solder joint. The degree of wetting, the microstructure (in particular the intermetallic layer), and the inherent... more
Reflow profile has significant impact on solder joint performance because it influences wetting and microstructure of the solder joint. The degree of wetting, the microstructure (in particular the intermetallic layer), and the inherent strength of the solder all factor into the reliability of the solder joint. This paper presents experimental results on the effect of reflow profile on both 63%Sn
Research Interests:
This paper presents the drop test reliability of 0.5 mm pitch lead-free chip scale packages (CSPs). Fifteen 0.5 mm pitch CSPs were assembled on a standard JEDEC drop reliability test board with Sn3.0Ag0.5Cu lead-free solder. Eight boards... more
This paper presents the drop test reliability of 0.5 mm pitch lead-free chip scale packages (CSPs). Fifteen 0.5 mm pitch CSPs were assembled on a standard JEDEC drop reliability test board with Sn3.0Ag0.5Cu lead-free solder. Eight boards were edge-bonded with a UV-cured acrylic; eight boards were edge- bonded with a thermal-cured epoxy; and twelve boards were assembled without edge bonding.
Research Interests:
Reflow profile has significant impact on solder joint performance because it influences wetting and microstructure of the solder joint. The purpose of this study is to investigate the effects of reflow profile and thermal shock on the... more
Reflow profile has significant impact on solder joint performance because it influences wetting and microstructure of the solder joint. The purpose of this study is to investigate the effects of reflow profile and thermal shock on the shear performance of eutectic SnPb (SnPb) and Sn3.0Ag0.5Cu (SAC305) solder joints. Test boards were assembled with four different sized surface mount chip resistors (1206, 0805, 0603 and 0402). Nine reflow profiles for SAC 305 and nine reflow profiles for SnPb were developed with three levels of peak temperature (12ºC, 22ºC, and 32ºC above solder liquidus temperature, or 230ºC, 240ºC, and 250ºC for SAC 305; and 195ºC, 205ºC, and 215ºC for SnPb) and three levels of time above solder liquidus temperature (30 sec., 60 sec., and 90 sec.). Half of the test vehicles were then subjected to air-to-air thermal shock conditioning from -40 to 125°C. The shear force data were analyzed using the Analysis of Variance (ANOVA). The fracture surfaces were studied using...
