Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Design Guide

GregH

#19708

Design Guide | 29 April, 2002

If IPC-SM-782 is for Surface Mount Land Pattern, what is the Standard used for Through Hole Guide (eg. Component Lead Thickness versus Hole diameter etc.), where can I find them?

thanks

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Bob Willis

#19709

Design Guide | 29 April, 2002

The basic guidline is lead size plus 0.010" which you can also use for through hole reflow/intrusive reflow. Most suppliers of the insertion equipment quote this as the minimum clearance hence its a good guide.

Druing recent trials for through hole or odd form assembly with surface mount placement systems hole to lead clearance has also been quoted as a minimum of 0.008" but you must consider the tolerance of leads and the PCB.

There is a PCB Design For Manufacture CD and video in the SMTNet book shop you may care to check out.

Bob Willis, Airport Lounge on his way to San Jose

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GregH

#19729

Design Guide | 29 April, 2002

Thanks Bob! It gave good views..

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#19735

Design Guide | 29 April, 2002

There is no PTH analog to 782 done by IPC. The thinking could be PTH designs are: * Over designed, as is. * Established in practice and the IPC wouldn�t make much money selling such a standard.

Alternative are: * Machine suppliers, for instance: 'Design Guidelines For Leaded Component Insertion' by Universal Instruments Corp. * Smart guys: Bob Willis, Earl Moon, Jim Blankenhorn [search the fine SMTnet Archives for contacts]

As an aside, be aware that IPC is replacing 782 with a much improved version [IPC-7351] is either on or soon to be on the streets. It was done along the lines of design approach that Jim Blankenhorn has taken for years. => One size does not fit all. There are classes of products and there should be classes of pads.

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