Not Just Chips: Challenges to Develop a Reliable Lead Free Solder Column To Replace Solder...

Challenges to Develop a Reliable Lead Free Solder Column To Replace Solder Balls in Large Heterogeneous Packages
Martin ("Marty") Hart
Topline Corporation
Solder balls are well suited for interconnecting normal sized ball-grid array (BGA) components to printed circuit boards (PCB).
However, solder balls may be subject to failure (delamination) caused by excessive stresses inherently found in super-sized Heterogeneous 2.5D packages.
In particular, the growth trend is to make larger and larger BGA processors often exceeding 60mm square in size for hyperscale data centers.
Currently solder column technology is approaching 40 years old and is limited to employing Tin-Lead (SnPb) alloys.
The challenge is to make Lead Free solder columns that satisfy demand for RoHS compliance, while still providing adequate stress relief to enable very large packages and extend the operational life of the system.
We are developing a next generation of solder columns with an exoskeleton copper braided sleeve to make it possible to build fully Lead Free compliant interconnects to replace solder balls for use on large sized Heterogeneous processors.
Our Lead Free non-collapsible Braided Solder Columns reduce the stress between the package and the PCB. Their unique copper sleeve construction also offers lower thermal impedance, as compared to solder balls, possibly reducing the need for a heavy heat sink on top of the chip.
We are extending this technology to support the market trends to scale up the size of chip packaging while maintaining reliability.
In addition to the market and technical requirements, we will be presenting our work to extend the technology along with initial characterization data.