There are a couple of ways. In the back of the IPC-A-610 there is a standard
improvement form. You can FAX it to the IPC. You can also contact Jack
Crawford ( [log in to unmask] ) with your proposed change and rational. It
is very helpful if you identify the clause you want changed, propose a new
requirement, and explain why you think the change is an improvement.

I see your point. I guess you might get parts with insufficient bend,
causing a gap underneath the component lead. Solder results would be poor
because of insufficient solder volume. I don't know how the committee would
reach on consensus for that case. I think they would lean toward rejecting
the components.

> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Daan Terstegge
> Sent: Friday, July 30, 2004 3:19 AM
> To: [log in to unmask]
> Subject: Re: [TN] Toe-down configuration for gull wing leads
>
> Hi Guy,
>
> Also larger packages sometimes have their leads bent in such
> a way that it makes a really huge difference whether the
> fillet should extend to the mid-point of the lead bend or
> not, and even with thick stencils and long solderpads it is
> not always possible.
> I don't think there's a mistake, but the exact definition of
> "toe-down configuration" should be included the spec,
> otherwise you can call everything "toe-down" even when the
> angle with the pad is 0.0001°. But from the A-610 and
> J-STD-001 it seems that toe-down is not the rule but the
> exception to the rule.
> So how can I contact the comittee ?
>
> Daan Terstegge
>
> >>> [log in to unmask] 07/29/04 11:41pm >>>
> The standards Both J-STD-001 and IPC-A-610 (C not B) say that
> the solder must extend to the mid-point of the outside of the
> lead bend. It is possible to achieve this condition if the
> land pattern and solder stencil are properly designed. There
> is a pretty large process window, as this lead configuration
> is generally associated with low lead packages and the
> maximum solder condition allows solder to extend under and
> touch the component body.
>
> If you think there is a mistake in the standard, now is the
> time to act. The committees are well along in the development
> of revision D.
>
>
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Charles Caswell
> > Sent: Thursday, July 29, 2004 5:24 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] Toe-down configuration for gull wing leads
> >
> > J-STD rev.B in front of me. You are correct, it does say to the
> > midpoint of the lower bend radius. My opinion is this is a mistake.
> >
> > -----Original Message-----
> > From: Daan Terstegge [mailto:[log in to unmask]]
> > Sent: Thursday, July 29, 2004 3:03 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] Toe-down configuration for gull wing leads
> >
> >
> > 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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