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Through holes



Through holes | 9 May, 2002

Could someone provide help regarding IPC's recommendation on Plated Through hole's --- lead to hole ratio. I can't find it in IPC-2221 and IPC-SM-782.

Thank you very much

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Through holes | 9 May, 2002

First, SM-782 elates to surface mount pads. So, expecting to find PTH design rules there is a bit of a stretch.

Search the fine SMTnet Archives for similar threads. For instance here�s one from last week:

Additionally, �DFM For Through-Hole Technology� [Vivek Sharma, Printed Circuit Design, 1/01, p 14-20] is a good general point of reference.

Finally, 2221, 8.3.1 Leads Mounted In Through-Holes says, �Requirements for lead-to-hole relationships are detailed in 9.2.3 through 9.3 of the related design sectional.� This makes sense because you�d expect that relationship to change according to the type of board [ie, rigid organic, flexible, etc].

As an example, 2222, Table 9-4 Plated-Through Hole Aspect Ratio has the information you seek for rigid organic boards. Leading-up to that table, 2222 goes into a rather involved discussion on the proper gap between lead and hole according to product class. This is too burdensome to discuss here and not knowing the type of board you�re designing or the equipment class could be a waste of time anywho.

Consider obtaining the section design standard for the type of board you are designing to compliment and expand on 2221.

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