The Universal PCB Design Grid System
Paper reviews reviews one of the single most important aspects of the electronics industry - The PCB Design Grid System.
Materials Tech
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Authored By:
Tom Hausherr
Valor Computerized Systems
Summary
Mixing PCB Design Layout units will compromise perfection every time. PCB Design perfection starts with building CAD library parts and quickly moves to part placement, via fanout and trace routing challenges. Outputting data for machine production can be extremely complex or very simple based on the PCB Design Layout units that were used throughout the PCB design process. This paper reviews one of the single most important, but sometimes overlooked or taken for granted, aspects of the electronics industry - The PCB Design Grid System
Conclusions
The Universal PCB Design Grid System is based on the 0.05mm unit. All shapes and sizes for every aspect of the PCB layout should be in increments of 0.05mm. Transitioning to the metric system for PCB layout is necessary to achieve electronic product development automation. The United States is now the only industrialized country in the world that does not use the metric system as its predominant system of measurement. However, PCB design worldwide has been driven historically by the component manufacturers and CAD vendors to use the Imperial measurement system. Clearly, U.S. companies that do not produce products or services to metric specifications will risk being increasingly noncompetitive in world markets.
Japan has identified the U.S. lack of metric usage as a strategic impediment to access of U.S. products to the Japanese home market. In addition, consolidation of the European market product standards will make sales of non-metric products increasingly difficult and uncertain. Most U.S. companies understand that using metric units is essential to future economic success. Their hesitation may be due to uncertainty as to when and how to convert. Through their actions, U.S. federal agencies are demonstrating an increasing determination to use the metric system of units in business-related activities.
Example: Most component manufacturers have converted their component dimensional datasheets to millimeter units. Many of the results are not yet very visible to the public, which is not a direct target of current federal transition activities. Most veterinary and medical institutions have completed the transition to metric units however, industry is the main target, and is becoming increasingly aware of and generally welcomes the government's progress. Industry acceptance of the wisdom of proceeding with the metric transition is due partly to the realization that producing to metric specifications and surviving in tomorrow's economic environment are synonymous. Most companies today export their products to a global market where metric based products are expected
Initially Published in the IPC Proceedings
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Comments
Just read your article pertaining to the "Universal PCB Design Grid System". While I agree with your position stated in the article I do not approve of your math as stated on the last page. All of those metric/mil conversions are wrong. Like so many other people, those values are derived and rounded from not using 5 decimal places when converting. 5 mils = .127mm, not .125mm. Otherwise, good article, and thanks.
Roger Castro, Wireless Seismic, USA
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