Ask the Experts
April 30, 2007 - Updated
July 4, 2007 - Originally Posted

Through-hole ratios for PCB's

In Through Hole technology, what is the best lead to hole ratio to be maintained? Is the lead to hole ratio the same for any kind of PCB finishes or does it vary? What should be the pad size on the primary side and secondary side?


Expert Panel Responses

We ran some recent tests and reported at APEX 06 "Lead Free Intrusive Reflow" by Coleman and Oxx. In this study 1:1.3 and 1:1.4 provided good results while greater than 1:1.5 gave voids or insufficient fill. I don't have information on Wave Solder process.

Bill Coleman
Vice President Technology
Photo Stencil
For over 18 years, Dr. Coleman has been the vice president of technology for Photo Stencil, working closely with customers to understand their printing requirements. His efforts have resulted in several new stencil products.
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