Polymer Ball Interconnect - A
The use of plated polymer cored balls to replace solder balls in BGAs and CSPs has been developed and trailled over several years but has yet to see signifcant take up in the industry. However with larger ceramic components presenting increasingly challenging long term reliability concerns the flexible nature of polymer ball technology is becoming increasingly attractive.This project looked into latest products from two polymer ball manufacturers, including multiple polymer compositions, coatings and soldering methods. Bend testing and thermal cycling were conducted on different size ceramic BGAs. The project team was made up of member companies from across the supply the supply chain.
Polymer Ball Interconnect technology is a recent development designed as replacement to traditional solder balls in ball grid array and chip scale component packaging. The technology offers the potential for improved package to PCB joint reliability, particularly in hand held and portable applications where mechanical shock test resistance is a critical design criterion.
Cross section of a polymer core BGA solder ball attached to a printed circuit board
The technology consists of an accurately produced, polymer based, spherical core which is metalized with a solderable external finish. The balls are attached to both component package and PCB using conventional mass soldering techniques.
The technology is still in its infancy but several packaging companies are showing interest.This project has the objective of assessing the feasibility of polymer ball interconnect by exploring demand and specific business/technical requirements as well as conducting preliminary practical reliability assessments of the technology.
In order for the polymer ball interconnect to become universally accepted in the component packaging industry the technology must be demonstrated to meet mechanical and electrical requirements as well as satisfying commercial expectations. As these requirements are not currently clearly defined the project will be structured to identify industry needs. A demonstrator will then be developed and tested to evaluate the capabilities of polymer ball interconnect to meet these requirements.
Assess polymer core ball technology as a viable component packaging alternative to SAC solder balls for large ceramic CBGAs.
- Drop in (or near drop in) technology for balling process
- Reliability performance – ATC and monotonic bend testing
The project leveraged the expertise of the HDPUG member companies to identify the key criteria that the polymer ball interconnect technology should be assessed against. A working team was formed with inputs and support from team members representing a broad spectrum of the electronics manufacturing supply chain, including materials and component suppliers, PCB fabricators and assemblers and OEMs / systems integrators.
Several test vehicles were designed to enable a direct reliability performance comparison between SAC solder balls and polymer cored balls for a range of components. Accelerated thermal cycling, drop testing and monotonic bend testing will be used to evaluate component to board interconnect integrity.
Project activity flow chart