Probe Heatmap Tool Helps EMS Company Pinpoint a Costly Issue

 Bringing a new product to market requires agility and speed. That typically means streamlining the testing process to keep production costs and downtime under control. But when an unknown issue caused a low first pass yield (FPY) on a new printed circuit board assembly (PCBA), the electronics manufacturing services (EMS) company that makes it turned to Keysight. Its PathWave Manufacturing Analytics solution helped the company identify the problem.

The Key Issue: Identify and Resolve the Root Cause of Low First Pass Yield

A global EMS company based in China makes a computing PCBA for a large original equipment manufacturer. The PCBA is in the new product introduction stage and will move to mass production soon. However, a pin contact issue in the in-circuit test (ICT) station was resulting in FPY as low as 76%. This would have a huge impact on production, which the company expects will reach as many as 1,500 boards per line per day. Because of the low FPY, the existing systems would not meet the volume demand per day. The EMS company would have to add systems to the production line to meet the target volume. In a typical scenario, the EMS company executes a pin test upon board failure. This helps in overall test throughput; the test team assumes production boards are good and do not require the pin test.

Only boards with failure are subject to a pin test, which incurs additional test time. Knowing it had a pin contact issue, the EMS company had no choice but to execute a pin test for every board.

To overcome the low FPY the pin contact issue caused, the EMS company implemented the following measures:

Modifying the test plan to actuate (turn on and off) the fixture three times before the test begins This helps achieve better pin contact between the test points and the fixture (beds of nails)

Implementing a retest using Keysight’s Intelligent Yield Enhancement Test up to three times

Scheduling more frequent tester/fixture maintenance, including probe replacement, to maintain good probe condition

These measures added test time and cost while reducing production throughput. And the EMS company was still unable to identify the root cause. It could only work around the problem.

The Solution: PathWave Manufacturing Analytics

Keysight approached the EMS company with its PathWave Manufacturing Analytics solution. Keysight, the domain expert in ICT testing, was confident it would be able to identify the root cause and resolve the pin contact issue. The EMS company used PathWave Manufacturing Analytics to leverage and analyze big data collected from the ICT datalog files (including both pass and fail measurements) of every board. PathWave Manufacturing Analytics unlocked a new level of transparency to determine the issue.

During testing, the user was unable to see the measurement trends, especially the passing measurements. If a test is passed, that meant the measurement was within the upper and lower limits. However, the user did not know if the passing measurement was too close to either the upper or lower limit, which may contribute to false failures. The user would replace the probe only when the test started failing. This resulted in more unplanned downtime, reducing productivity and lowering overall equipment effectiveness (OEE).

Degradation anomaly detection in PathWave Manufacturing Analytics can determine probe deterioration via test measurement. Once PathWave Manufacturing Analytics detects a measurement deterioration trend away from the main population, it triggers an alert. The user can then plan to replace the probe — before failure occurs — during breaks, shift changes, or scheduled downtime. This process converts unplanned downtime to planned downtime, maximizing machine uptime and resulting in a higher OEE score.