-
- News
- Books
Featured Books
- pcb007 Magazine
Latest Issues
Current IssueFueling the Workforce Pipeline
We take a hard look at fueling the workforce pipeline, specifically at the early introduction of manufacturing concepts and business to young people in this issue of PCB007 Magazine.
Inner Layer Precision & Yields
In this issue, we examine the critical nature of building precisions into your inner layers and assessing their pass/fail status as early as possible. Whether it’s using automation to cut down on handling issues, identifying defects earlier, or replacing an old line...
Engineering Economics
The real cost to manufacture a PCB encompasses everything that goes into making the product: the materials and other value-added supplies, machine and personnel costs, and most importantly, your quality. A hard look at real costs seems wholly appropriate.
- Articles
- Columns
Search Console
- Links
- Media kit
||| MENU - pcb007 Magazine
How to Feed Test Data Back to Engineering for Process Improvement
August 1, 2019 | Todd Kolmodin, Gardien ServicesEstimated reading time: 3 minutes

Some people think of the PCB manufacturing process as a black box: design data goes to the manufacturer (fabrication house), and magically, the finished PCB is produced. While it may have been like that in the past—such as manufacturing in the ‘80s, which now looks archaic and sometimes unbelievable—in actuality, fabricating PCBs today is quite a ballet of processes. All of the complex steps must be taken in place and in sync to deliver a successful product. The challenge is to identify and feed back as-built testing information to help optimize the design data over time.
Today, as in years past, the OEM design is sent to the manufacturer for processing. There, the design data is massaged to produce the required PCB within the fabrication modes and methods of the manufacturer while still producing the required end product. Now, however, this same design data is also used in other processes throughout the manufacturing process in addition to creating the photo-imaging data and CNC drill/route programs.
This same design data drives other quality control processes too. There are tools and software programs in the verification processes that utilize this same customer supplied data to drive the quality control feedback loop. The design data is used to verify inner layer and outer layer circuits, such as in the AOI and AVI processes (automated optical and visual Inspection). The design data also drives electrical test (ET) processes.
Now, in the PCB manufacturing arena, the ET game has changed considerably. To close the quality feedback loop, even more checks must be included with the board design’s tooling. And the new ET results data requires new presentation methods for an efficient response from the inspectors.
Getting Here From There
Back in the ‘80s, most ET was done by means of “self-learning” a board and then comparing it to the rest of the lot; there was no such thing as netlist test. The risk was extreme with this method because the testing standard relied on a “known good board” to use as the master. If there was no gold-standard board to use, then testing had to make do with a learned comparison test on a sample from the build lot. The risk that the sample board was bad was significant, setting up the age-old “two wrongs make a right” scenario. For example, if the board had a repeating film defect that affected the entire lot, the learn comparison test for ET would have been performed on a bad board. As would be expected, when a bad board is learned and tested against an entire lot of bad boards, they all “pass.” More than once, this false-premise test data resulted in catastrophic failures at the assembler and a 100% reject back to the manufacturer.
Complicating matters in the ‘80s were the challenges of ET verification. The fixture or grid testers of the day supplied fault data in an X-Y grid coordinate system based on the test fields of the machine. The fixtures used pins that matched the footprint of the PCB and translated down to the X-Y grid where the machine learned the electrical signature of the board. When opens or shorts were detected, they were reported in the X-Y grid. This results data had to be translated by hand to identify the locations on the board where the fault was reported. This was usually done with the help of a mylar grid overlay that the inspectors placed over the board and a datum point identified on the fixture to match to the PCB. The difficulty for the inspectors was in properly identifying the locations on the PCB that the machine had reported. Multimeters or “beepers” were used to ring out the probable fault and determine whether it was an open or a short. This methodology was risky and could easily lead to misdiagnosing a fault, which would then result in an escape.
To read the full article, which appeared in the July 2019 issue of PCB007 Magazine, click here.
Suggested Items
Husqvarna, Flex Announce Strategic Partnership
02/07/2025 | FlexHusqvarna and Flex announced a strategic manufacturing partnership, which will enable Husqvarna to further enhance flexibility, efficiency, and time to market through Flex's strategic supply chain management solutions and expand Flex's Lifestyle portfolio into outdoor and power equipment.
AIM Solder Acquires the Assets of Canfield Technologies
02/07/2025 | AIM SolderAIM Solder, a leading global manufacturer of solder assembly materials, is pleased to announce the acquisition of the assets of Canfield Technologies, a renowned producer of high-quality solders and fluxes since 1844.
New IPC White Paper Focuses on Use of Artificial Intelligence in Automated Optical Inspection in Electronics Manufacturing
02/06/2025 | IPCA new white paper, “Unlocking AI for Automated Optical Inspection” released today by IPC’s Chief Technologist Council, focuses on AI’s role in AOI processes for printed circuit board assemblies (PCBAs). According to data within the white paper, recent advancements in technology, particularly in Cloud AI, IoT and Smart Manufacturing, have provided opportunities to further enhance AOI performance.
I-Connect007 Editor's Choice: Five Must-Reads for the Week
02/07/2025 | Marcy LaRont, I-Connect007For my top picks this week, I wanted to highlight some other important content we’ve featured. First is the incomparable Stephen Chavez, who provides insight into what the future PCB designer will look like. Bob Duke of American Standard outlines the seven key challenges he sees in offshore manufacturing. We move seamlessly from there to tariffs, one of today’s most talked about topics. Jeffrey Beauchamp of NCAB looks back at a recent timeline regarding tariffs, and it’s quite interesting. I’m also pointing you toward a feature on a thriving EMS company in Malaysia, one of the two most popular locations for China Plus One manufacturing expansions. Finally, we acknowledge the expansion news of a long-time PCB and EMS global supplier.
Geopolitics Reshapes the Global PCB Landscape as Trump 2.0 Looms
02/06/2025 | TPCAThe global PCB industry is undergoing a period of significant transformation driven by geopolitical shifts, protectionism, and supply chain restructuring.