This is the most debated IPC acceptance topic we have with customers- completely wetted top fill requirements. Even after explaining that the acceptance criteria is based on what is consistently achievable with typical manufacturing methods, customers still demand above and beyond IPC-610 and we have to top fill, by hand, every hole that isn't completely filled and wetted. Pins connected to a ground plane without thermal relief (by their design) are especially fun...
Ron
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: Thursday, March 17, 2016 10:54 AM
To: [log in to unmask]
Subject: Re: [TN] Hole Fill and Thermal Relief
Thanks Ed,
I was looking at 7.3.5.2 from that same document that declares "Less than 180degree wetting" as a defect for Class 2 and "Less than 270degree wetting" as a defect for Class 3.
The words say "lead to barrel wetting"
but pictures look like they are pointing to land wetting.
I would hate to be an inspector trying to evaluate that, especially if I'm looking at a hole that is only 75% full
Jack
On Wed, Mar 16, 2016 at 4:36 PM, Ed Popielarski <[log in to unmask]>
wrote:
> IPC-A-610-F Table 7-4 Line C states: "Percentage of land area covered
> with wetted solder on solder destination side (see 7.3.5.3)" = 0% for
> all classes.
>
> Ed Popielarski
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> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
> Sent: Wednesday, March 16, 2016 2:25 PM
> To: [log in to unmask]
> Subject: Re: [TN] Hole Fill and Thermal Relief
>
> no, I'm not referring to vias.
> I'm trying to solder a connector into plated through-holes.
> IPC-A-600 7.3.5.1 allows a partial fill, see Figure 7-84
>
> In the next section
> IPC-A-600 7.3.5.2 requires wetting on the DESTINATION side which
> implies the hole is FULL of solder
>
> How can you have ANY destination side pad wetting on a PARTIALLY
> filled (but still ACCEPTABLE) hole?
> Those two seem incompatible, so I'm sure I'm misunderstanding.
>
> What's worse is Figure 7-91, which shows a solder joint not wetted to
> the lead.
> How could you ever know how far down the UNWETTED portion extends into
> the hole?
> (It IS labelled as a defect, I agree, but it still might be 75% wetted
> down the barrel) So you have a 360 degree wetted pad labelled as a
> defect because you can see the unwetted lead, but how can you APPROVE
> a 75% filled hole that you CAN'T see if it is wetted or not?
>
> Jack
>
>
>
>
>
> On Wed, Mar 16, 2016 at 2:57 PM, <[log in to unmask]> wrote:
>
> > you mean something like this?
> >
> > http://www.cree.com/~/media/Files/Cree/LED%20Components%20and%20Modu
> > le s/XLamp/XLamp%20Application%20Notes/XLamp_PCB_Thermal.pdf
> >
> > filled via vs partially filled do have difference. you might need
> > x-ray inspection... my 1.4 cents.
> > jk
> > > Maybe I should know better than to ask two questions in the same
> > > email, but they're related...
> > > I got into a discussion about the hole fill requirement for some
> > > large through-hole power devices and connectors. The supplier is
> > > worried about using a "percentage" hole fill measurement, because
> > > he says that even if the hole is 75% full (or whatever percentage
> > > we want to use) the hole
> > wall
> > > will not be WETTED 75%. He maintains that the cold solder can
> > > extend up farther than the actual portion that makes a good joint.
> > > So he is looking at the TOP PAD WETTING for verification of a good
> > > solder joint, even though we don't require it.
> > >
> > > Q1) It seems like an inspection procedure looking for WETTING
> > > instead of HOLE FILL is not what is intended in IPC, but does he
> > > have a point? The hole fill problem is with Selective Soldering,
> > > not Reflow
> > >
> > > Q2) Wanting to provide bare board designs using good DFM
> > > practices, I would be willing to reduce my thermal spoke widths so
> > > the solder will flow better, but I can't find a calculation that
> > > would tell me what I need for something like 10A. There is nothing
> > > about this in the IPC-2152 Current Carrying standard. Is there a
> > > rough guideline I can use for current through planes using thermal relief??
> > >
> > > thanks
> > > Jack
> > >
> > >
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