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Chip Scale Review September • October • 2018

[ChipScaleReview.com]

with respect to any final inspection process. Keeping this process

in place without the need for mechanical dicing screening just adds

unnecessary cost to the final product.

Step 3.

Step 3 is to strategically implement a final inspection

capable die attach or tape and reel process to successfully screen parts

for issues encountered during die pick processing. In general, die are

processed without issue during the full front-end-of-the-line (FEOL)

flow only to be damaged during the die pick process. Once this process

is complete, detection capabilities today are limited. Implementing

visual inspection at this point in the process with a control system to

flag lots that have pick issues or trigger limits puts a system in place to

control and prevent the customer from receiving damaged parts.

Summary

A drastic change is needed in the semiconductor back end assembly

flow. With today’s push toward higher resolution images, today’s

processes are creating cases where overkill and dispositions are

becoming a way of life for the back-end-of-line (BEOL) assembly areas.

This trend cannot continue long term, as fundamental changes

with the dicing processes and technologies used continue to

improve. This article discussed the use of new dicing technologies

and proposed the elimination of long-standing expensive

inspections that still typically do not prevent or contain damage

created at the pick processes downstream. The key to solving the

challenges is to fix these chipping issues, and direct process controls

and containment procedures at the die attach and tape and reel level

to detect out of control set-ups and pick issues during processing.

Our collective goal is to eliminate chipping at the source and

redirect the focus of long-standing inspections to stop and contain

downstream processes. If we do that, we can resolve the many

“dppm” issues our industry experiences today, which are where

the majority of the challenges arise when customers raise the flag.

Reference

1. M. Todd Wyant, “Wafer chip-scale package cost reductions,”

Mar/Apr 2015,

Chip Scale Review

, Vol. 19 No. 2, pp. 54-56.

Biography

Todd Wyant earned a BSME from Purdue U. in Mechanical

Engineering and a Six Sigma Black Green Belt from AIT; he is the

Manufacturing Technology Manager at Texas Instruments; email

m-wyant@ti.com

Figure 5:

a) Fault tree for chipping factors; b) Common edge chip; c) Corner

crack examples.