In its continuous quest to deliver reliability-enhancing materials for today’s advanced devices, Henkel Corp. has engineered a cost-effective CornerbondTMunderfill material for BGA and CSP devices.

The new material, Loctite®3508, is a one-component epoxy that is pre-applied to the board at the corners of the CSP pad site using a standard dispensing system. Unlike capillary flow underfills that require dedicated equipment and subsequent process steps, Henkel’s Loctite 3508 can be applied in-line with existing capital equipment with curing taking place during the normal solder reflow process, thus delivering considerable cost savings and dramatically improving throughput.

While next-generation capillary flow underfills remain the best option for drop-test protection of BGAs and CSPs used in modern handheld devices, Henkel’s Loctite 3508 material is the most cost-effective solution for packages within other mobile products - such as laptops and gaming consoles - that may experience only occasional vibration. As the material is cured during solder reflow, Loctite 3508 was specifically designed to be compatible with this process and the higher temperature requirements of lead-free manufacturing. The BGA solder reflow process dictates that solder balls collapse and self-center so that proper interconnections between the device and the board can be formed. When adhesives that were not designed for this process are used as corner support materials, self centering does not occur, thus resulting in poor interconnections and solder joint opens and fractures that may cause decreased reliability or total device failure.

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