We use a lot of mix technology PCB, double and single side.  Their may be
an IPC spec for lead to hole diameter, but it may depend on if you are
machine inserting the components.  Some machines may call out a minimum of
0.016" larger hole diameter than lead diameter.  A good rule is that hole
diameter should be no less than 0.004" plus the lead diameter (ex .0.038"
lead + 0.004 (space)  = 0.042" (hole) and should be less than 2.5 times the
lead diameter to promote capillary action of solder. Look out for small
annular rings if hole are being redrilled ( no design rules violation -
less than 8 mill have created problems if units are to be reworked.


Tom Braswell
Fawn Industries, USA

----------
> From: Vinit Verma <[log in to unmask]>
> To: [log in to unmask]
> Subject: [TN] Lead dia to Hole Dia ratio
> Date: Tuesday, December 08, 1998 6:43 AM
>
> Hi Technetters,
>
> Anybody using power diodes in a mixed tech. (SMT + Leaded) PCB, single
> sided, FR2 material?
>
> What is the Lead Dia to Hole dia ratio normally used by all of you in
case
> of POwer diodes? Otherwise also what ratio is most oftenly used?
>
> Thanks in advance
>
> Regards
> Vinit Verma
> Ph: 0124 372721,2,3(O)  Fax: 0124 372724 (O)
>     011 7871747 (R)          011 5783571 (R)
>
> --------------------------------------------------------------
> Bharti Telecom Limited, Gurgaon, India
>
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