Pan Pacific Symposium Conference Proceedings


Author: Guenter Schiebel
Company: Siemens Logistics and Assembly
Date Published: 2/25/2005   Conference: Pan Pacific Symposium

Abstract: Within advanced electronics assembly based on flip chip and chip-on-board (COB) with wire bonding the economic transfer of the required materials, such as fluxes and adhesives into the process is a critical issue. Dispensing, integrated in assembly equipment, is known as a standard.

With dispensing, doubtless, a drawback is the fact that the process is time-consuming. For flux application within solder reflow flip chip technology the dispensing principle lost importance and is nearly out of use. Flux application by dipping currently is the mainstream. In general, dip fluxing processes are clearly limited to area array type packages, such as CSPs and flip chips.

When the bottom side of packages, such as bare dies for COB or area array packages with wafer applied fluxing underfills have to be dipped over the full area into the process specific, tacky material, standard dipping cannot be used anymore. The placement machine's vacuum nozzle, in most cases could not reliably lift the package out of the tacky material.

In order to reduce manufacturing costs by improving throughput, in many chip assembly applications it makes sense to apply the relevant process material directly onto the component immediately prior to placement. The application of highly tacky (viscous) material is possible by using a specific dip process, where a special lift mechanism supports the vertical movement of the package out of the tacky material (patent pending).

The paper describes the principle of that specific dipping process and a variety of interesting special dipping applications including wafer-applied fluxing underfills (WAFU), economic application of adhesives for bare dies for COB with wire bonding and a specific assembly equipment calibration during production (patent pending).

Another interesting opportunity of transferring materials into assembly processes (e.g. adhesive for COB with wire bonding) is based on the stamping principle. The paper as well discusses the possibility to transfer process materials onto packages inside assembly machines based on the ink-jet principle (patent pending).

Key words: Stamping, dipping, fluxing underfill, ink jetting.

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