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Design for test has traditionally been viewed as the last checkpoint before a product enters production. Bert Horner's The Printed Circuit Assembler's Guide to... Design for Test challenges that thinking. In his book, he argues that testability should influence every stage of PCB and CCA development, from the first schematic through layout, manufacturing, inspection, and long-term product support. The result is a practical guide that connects engineering decisions with measurable manufacturing outcomes.
Here are three key takeaways from the book:
1. Good testing begins with good design.
Test access, component placement, and inspection strategy aren't manufacturing details to solve later; they're design decisions that determine how efficiently a product can be verified and supported. Building those considerations into the design process reduces troubleshooting, shortens debug cycles, and helps prevent expensive redesigns before production ever begins.
2. Effective testing relies on complementary methods rather than a single solution.
Horner explains how boundary scan, built-in self-test, flying probe, in-circuit test, automated optical inspection, X-ray inspection, and functional testing each reveal different types of defects. The real value comes from combining those methods into a layered strategy that balances coverage, cost, and manufacturing efficiency, rather than relying too heavily on any one technique.
3. Everyone shares responsibility for testability.
This guide’s focus is on people as much as process. The PCOLA-SOQ framework provides teams with an objective way to measure inspection and test coverage while reinforcing the need for collaboration among design, manufacturing, quality, and leadership. When everyone shares responsibility for testability, improvements in first-pass yield, product reliability, compliance, and time-to-market become far more achievable.
The technology behind modern electronics will evolve, but the principles behind effective testing remain remarkably consistent. Organizations that make testability part of the design process, not an afterthought, will spend less time finding problems and more time delivering reliable products with confidence.
If you haven't already, be sure to download The Printed Circuit Assembler's Guide to... Design for Test and other titles from the I-Connect007 book library.
