SMTA International Conference Proceedings

Probe Technologies To Improve First Pass Yields

Authors: Brian Crisp, Ken Snyder and Tom Merline; Brook Sandy-Smith
Company: Everett Charles Technologies and Indium Corporation
Date Published: 10/13/2013   Conference: SMTA International

Abstract: Test coverage for printed circuit board assemblies (PCBAs) has decreased due to product miniaturization and other design constraints. To counter this trend, manufacturers have been using via structures for test access points, however, vias are not typically optimal test targets based on their finished geometry and tendency to accumulate residual flux material.

Also, the proliferation of new PCBA material finishes, including various types of OSPs and lead-free solders, has led to flux contamination challenges and other manufacturing issues, which complicate contact reliability during test.

These two trends are driving the test probe industry to develop new technologies to improve first-pass yield and help lower the cost of test in manufacturing by increasing throughput.

By leveraging its expertise in semiconductor probe technology, Everett Charles Technologies (ECT) has pioneered two “breakthrough” PCBA test probe technologies that significantly improve contact reliability and increase mean-time-between-replacement (MTBR). The first is LFRE. The industry standard for POGO® pin plating is gold electroplate alloyed with either cobalt or nickel to enhance its hardness. The hardness of 99.7% pure electroplated gold is increased from 90 Knoop to 130-200 Knoop when alloyed with nickel or cobalt. However, these gold alloys can still attract solder transfer and may exhibit premature tip wear from contemporary solders.

Conversely, LFRE plating is significantly harder than the industry’s standard gold plating, providing an impressive hardness range of 550 to 650 Knoop. It is also more durable and less susceptible to solder and material transfer.

A second development is ECT’s new EDGE™ test probe technology, used for contacting test pads and vias. The EDGE™ design incorporates “flat” steel LFRE-plated tips which are up to 10x sharper than conventional machined tips. EDGE also features an innovative new internal “microwipe” biasing technology.

Field studies have demonstrated the performance of these new technologies with up to a 50% increase in production cycle life.

Key Words: 

pogo pin, pogopin, test probe, test pin, spring probe, spring contact

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