I'm working on a consumer electronics product made primarily from injection molded plastic that encloses a PCB. I'm not sure of what tolerances I can expect from the PCB. I need a better understanding of tolerances so I can correctly define boss diameter sizes and spacing as well as all the other features that meet PCB to plastic. Does anyone have any info on this :?: :?: Thanks.
Hi Kenny, IPC is widely recognized as the governing standards organization by PCB manufacturers. IPC-2221 has tables that list, for example, the flexural modulus, tensile strength, thermal expansion, and glass transistion temperatures of many different pcb dielectrics. In the association's own words: "IPC-2221A is the foundation design standard for all documents in the IPC-2220 series. It establishes the generic requirements for the design of printed boards and other forms of component mounting or interconnecting structures, whether single-sided, double-sided or multilayer. Among the many updates to Revision A are new criteria for surface plating, internal and external foil thicknesses, component placement and hole tolerances. Expanded coverage is provided for material properties, dimensioning and tolerancing rules, and via structures as well as updated coupon designs for quality assurance. 112 pages. Released May 2003." They charge $65 for the latest copy and you can quickly get a downloadable version. Source(s): http://www.ipc.org
