The requirement is for a heel fillet only. Side and to fillets are
formed to exposed basis metals. While nice to have, they are not
required. Heel fillets are required and the specs are listed in
IPC-A-610D and J-STD-001D for Class 1, 2 and 3. The focus is on aquiring
a good heel fillet, as that is the part of the solder joint that is
formed with the finished surface of the lead. Side fillets and toe
fillets are suspect, at best, as the solder is forming an intermetallic
with oxidized basis metal.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of James Verrette
Sent: Thursday, August 09, 2007 11:54 AM
To: [log in to unmask]
Subject: [TN] Minimum toe fillet for SOT23-3 land pattern

What should be the goal toe fillet for an IPC 7351 land pattern with
density level C for a SOT 23 - 3 pin package?  (least protrusion,
highest density)

 

 

Jim Verrette

Electrical Engineer

 

 


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