Project: Polymer Core Solder Balls (PCSB) for Volume Manufacturing of High Reliability Electronics

The CO goal of the project is for CP to become a sought after supplier of high quality PCSBs (polymer core solder ball) to the electronics industry. First of all the project will develop a manufacturing process that can be up-scaled and industrialized for large volume manufacturing of the polymer core solder balls. The process will include all aspects of the manufacturing, from polymer core to finished solder plating, including characterization and quality control. Equally important is the activity to develop guidelines and "best practices" for use of these novel materials, as well as to evaluate and qualify the technology for use in large scale manufacturing of electronics. As a part of this project, plating techniques will be developed, including a puls-electroplating and autocatalytic silver plating process developed by Polymer Kompositer AB, which will be improved and adapted for use with barrel plating of polymer core balls. This process has in itself a number of applications, most importantly connected to plating of fingers and bus bars for solar cells, where the present screen printing of silver is much to expensive._x000D__x000D_It is well known that interconnect of electronic components is a serious bottleneck in the design and manufacturing of consumer electronics. “CTE mismatch between materials used in these packages becomes a reliability issue as the package size increases, and reliability assurance becomes problematic. Current technology road maps suggest that thermo-mechanical problems are becoming a key issue in packaging...” (Mario Loeffler, Circuit Tree, May 2006)._x000D__x000D_In the PCSB project, the consortium is performing ground-breaking work related to material technology that can have a significant impact on electronics manufacturing. By introducing a soft polymer core as the CO structural element in the solder ball for the Ball Grid Array (BGA) and Chip Scale Package (CSP), the result is an electrical interconnect with supreme mechanical flexibility. Hence the solder itself is exposed to substantially less mechanical strain during use. This allows more complex and advanced components to be mounted onto the PCB (or other substrates) combined with improved reliability thus eliminating the need for the costly underfill process. _x000D__x000D_The particular challenge in this project is to overcome the limits caused by the traditional solder balls used in area array packaging. Traditional BGAs and CSPs lack the compliance of leads previously used in the surface mounted and hole mounted devices. The balls are therefore subjected to stresses due CTE differences between component and PCB or to flexing of the PCB, for instance during drop test. _x000D__x000D_Polymer cored solder balls (PCSBs) or polymer ball interconnect (PBI), has been proposed as a more reliable alternative to solid solder balls for use in ball grid array (BGA) and chip scale package (CSP) interconnects by several research teams. Their potential advantages are dependant on their increased compliance compared with a solid solder ball, thereby reducing the stress level in the interconnection system both during thermal cycling and due to the shock loads occurring during impacts. The latter is of particular importance for hand held products assembled using lead free solders, which are much more brittle than traditional tin-lead alloys. It may also facilitate the adoption of array packages for safety critical applications in harsh environments._x000D__x000D_Last year Conpart finalised a pre project related to BGA/CSP balls in electronic interconnect. The project was supported by the programme “Nanotechnology and New Materials”, by The Research Council of Norway. In this project, Conpart has evaluated the technical feasibility of develop Polymer Core Solder Balls for BGA and CSP applications using our unique technology. A number of polymer particle technologies were evaluated, singling out a particular interesting candidate. This work was done in collaboration with Sintef and Microbeads AS, who also will be subcontractors in this project. With a plating technique based on a combination of chemical plating and electroplating using a barrel technique we were able to add sufficient amounts of copper (typically 15-20 micron) to the polymer core. Parallel to this feasibility evaluation we started an activity together with potential customers to better understand the interest from the market and their requirements both technically and commercially. The market interest turned out to be formidable, and a new major project was initiated within the High Density Packaging User Group, called Polymer Ball Interconnect (PBI). HDPUG is a nonprofit trade organization that offers memberships to companies involved in the supply chain of producing products that utilize high-density electronic packages. In this project, a number of large companies are involved in the evaluation, including SUN Microsystems, National Semiconductor, Freescale, Alcatel Lucent, ASE and Celestica, among others._x000D__x000D__x000D_

Acronym PCSB (Reference Number: 7083)
Duration 01/03/2012 - 28/02/2015
Project Topic The CO goal of the project is to develop high quality PCSBs for the electronics industry. The project will develop the balls from polymer core to finished solder plating, as well as to develop user guidelines and to qualify the balls for use in electronics manufacturing.
Network Eurostars
Call Eurostars Cut-Off 7

Project partner

Number Name Role Country
4 Conpart AS Coordinator Norway
4 Infineon Partner Germany
4 PK Plating Technology AB Partner Sweden
4 SWEREA IVF AB Partner Sweden