Interview with Chris Underhill, General Manager of Finetech USA

As annual cell phone production surpasses the 1 billion unit level and circuit complexity increases due to the integration of new families of components (PoP, PiP, etc.), the need to execute high-yield rework becomes an essential component for OEM producers. With this ever-increasing investment in PCB/substrate material, there is a cost-reluctance to discard cell phone PCBs that are found to be faulty during the manufacturing process.

How then do Finetech's products and services help to reduce manufacturing costs in this, the consumer market with the highest annual unit sales?

In three important ways, Finetech is able to offer key rework solutions to the OEM cell phone producers worldwide that establish rework as a value proposition � no longer the problem child of the manufacturing process.

1. Residual Solder Removal (sometimes called site-cleaning). It is essential not only to replace the faulty component, but also the solder left behind as the package is removed. Finetech's contactless solder removal module ensures �one-pass� cleaning of either the substrate or the component. It can be implemented as either a fully automated process, together with remove and replace functions, or as a stand-alone process step in a manual rework station.

2. Package proximity � �Closer and closer and stack them higher� seems to be the designers' mantra. How does this effect rework? Rework equipment vendors must follow this path with continual improvements to the thermal management capabilities of the heat delivery system. It is of no use to remove one component only to disturb several neighbors, thus multiplying the rework workload. The key is the ability to concentrate hot-gas (typically nitrogen) where it is needed and keep it away from where it is not. Finetech's COMISS� system, which controls component temperature by mixing heated and unheated gas, ensures minimal temperature overshoot � a failure that many systems exhibit. Such failures cause excessive localized heat, board warpage and reflow and disturbance of neighboring components.

3. Leadless packages QFN, MLF, etc. present additional issues, the foremost being the need to print solder paste on the component rather than the board. With pitches down to 0.35 mm (350 micron), efficient printing should be an integral process step in the rework cycle. Why try to print paste away from the rework system, attempt to transfer it �smudge-free� and then manipulate it into a rework nozzle? Too much material handling � too great a source of mishap. With Finetech's Print-and-Flip module, the leadless package is printed on the system using the same reflow nozzle to both remove the pasted component from the module and reflow it to the board.

Finetech provides manual to fully automated rework solutions for cell phone repair, which also include processes for shield can removal/replacement, as well as an integrated solder paste dispense.