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Sample Profile
Wafer Bumping is growing in importance with the increasing use of
flip chip packaging. The process involves depositing eutectic, high
lead or lead-free solder onto the
wafer to form bumps that are reflowed to form perfect spheres. Wafers
are diced and either packaged or attached directly to a circuit board.
With the transition from 200mm to 300mm wafers, the challenge to increase
yields becomes greater as each wafer’s value rises dramatically.
KEY PROCESS REQUIREMENTS
Temperature uniformity and atmosphere integrity are crucial to the
wafer bump reflow process. Any oxide formation can disrupt the subsequent
chip join processes. Two different processes, nitrogen with flux or
hydrogen/fluxless, can be used to control oxygen. The flux-based
process presents the challenge of integrating the flux coating
process and dealing with volatilized flux in the reflow process chamber.
The hydrogen process requires tight atmosphere control. Both processes
can be run at temperatures up to 400oC depending on the
solder type.
300mm processing will increase emphasis on maximizing yields and minimizing
scrap costs. Reducing wafer breakage will require robust automation
solutions for wafer level packaging.
PRODUCTS:
Pyramax | Controlled
Atmosphere Furnace | Flux Coaters
| Wafer Handlers
PROCESS:
Wafer Bump | Die Attach | Lead
Free
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