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July 2004

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Subject:
From:
Daan Terstegge <[log in to unmask]>
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Date:
Thu, 29 Jul 2004 22:02:52 +0200
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Hi Charles,

This kind of problem is exactly why I ask the question. Normal requirement
is indeed having an amount of solder in the heel which is equal to the
leadthickness (for class 3), but for toe-down the solder must extend to the
midpoint of the lower bend, which is -as you say- not always possible.
Therefore it is important to know if one has to look at the whole lead, the
last millimeter of the lead, the last 10th of a millimeter or whatever. When
(only) the last few mils of the tip of the lead are parallel to the pad,
would that mean it is no longer a "toe-down configuration" ?
Accepting your definition, my question would be: which part of the lead is
exactly defined as the "foot of the lead" ?

Daan

----- Original Message -----
From: "Charles Caswell" <[log in to unmask]>
To: <[log in to unmask]>; <[log in to unmask]>
Sent: Thursday, July 29, 2004 9:15 PM
Subject: RE: [TN] Toe-down configuration for gull wing leads


If the foot of the lead is not parallel to the pad it is toe down. The
solder
requirement would be one lead thickness, On toe down this does not usually
come up to the heel bend radius.I have trouble with this every time.
Inspectors want to see the fillet above the midpoint of the heel, but with
toe down it is not always possible or practical.

-----Original Message-----
From: Daan Terstegge [mailto:[log in to unmask]]
Sent: Thursday, July 29, 2004 12:12 PM
To: [log in to unmask]
Subject: [TN] Toe-down configuration for gull wing leads


Hi Technet,

The IPC-A-610 (and related specs) mentions special requierments for solder
joint heel fillets when the leads have a "toe down configuration". I was
wondering if a definition exists of what exactly a toe down configuration
is. If the last portion of the tip of the lead is not 100% parallel with the
solderpad but has a small angle, does that mean it's a toe down
configuration ?
You help is appreciated as always,

Daan Terstegge
http://www.smtinfo.net

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