Manoj,

This is a calculation that I found while teaching at ITT Tech from the
"Drafting for Electronics" text book.  I've found it works very well for
finding the minimum Center-to-Center pin spacing for leaded components.
By using some algebra, I shortened the one that was in this book to:

d  =  lead diameter
CL =  Component length

If d <=.027 inches:           7(d) + CL
If d >=.028 & <=.041 inches:        8(d) + CL
If d >=.042 inches:           9(d) + CL

Then round UP to nearest .100 inch for lead bending machines.  This
insures that the component won't break while bending the lead.  Also,
check with your manufacturer to find out what their lead bending
capabilities are.

It's been awhile since I looked at my notes, but I think this is
correct.  If you need more information about the text for reference, let
me know and I'll go through my library.

Hope this helps,
Cherie Litson
President, IPC Cascade Chapter
Senior PCB Designer, NYTEC
425-703-0441
425-883-3337 ext. 207
[log in to unmask]

-----Original Message-----
From: Manoj Viswambharan [mailto:[log in to unmask]]
Sent: Friday, May 11, 2001 4:59 PM
To: [log in to unmask]
Subject: [DC] Pin Length


I searched the several internet sites and couldn't find a standard that
covers the following question:

What is the MINIMUM pin length in order to be able to reliably solder a
through-hole component to the PWB?

The pin diameter is 25mils. Hole diameter is 40mils. Pad diameter is
hole
diameter + 15mils. Board thickness is 78mils.

Can you point me to a reference regarding this matter?

Thanks in advance for any assistance.

Regards,
Manoj Viswambharan
Principal Design Engineer
Village Networks, Inc.
[log in to unmask]

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