Pan Pacific Symposium Conference Proceedings


USING TEST OPTIMIZATION TO IMPROVE REWORK EFFECTIVENESS

Authors: Juan Coronado, et al.
Company: Flextronics International Inc.
Date Published: 1/26/2010   Conference: Pan Pacific Symposium


Abstract: Currently with increasing PCBA density and complexity, it has become challenging to produce higher yields. Sometime we have to face a large number of rework boards in manufacturing. We use Automated X-ray Inspection (AXI) and 2DX for finding the defective location and type for printed circuit boards, however most AXI machines were designed to test boards directly from the SMT line (not for rework board). We are faced with two questions: 1) How can we effectively use test machines to diagnose the defects? And 2) How can we reduce defects for the current SMT line with Real test data and results?

This paper will discuss the following:
1. The X-ray machine is a Non-Destructive method for detecting defects on PCBA boards. How can we effectively use different X-ray machines (AXI and 2DX)?
2. How can we reduce test time? Set right Algorithm and Threshold for programming; manual test mode only for critical parts; several programs are just for critical components.
3. Real time data feedback to line. Prevention is much more important than detection.

We have done the following:
1. Evaluated AXI, 2DX, AOI, and other test machines’ capability in order to understand their advantages and disadvantages, and to use them efficiently.
2. Kept the machines at the optimized conditions. Maintained AXI programs with high detection coverage and low false call ratio.
3. Performed sampling test for production boards at AXI.
4. For some critical parts, used individual program to test them at AXI or examine at 2DX.
5. Studied and analyzed the AOI, AXI, 2DX data, provided REAL time feedback to SMT line.
6. Used SPC data, focused main existing defects daily, found root cause, and solved issue as soon as possible with process, test and SMT programming engineers.

Key words: AXI, 2DX, AOI, SPI, Efficiency, and Yields.



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