Jack, with the 75% hole fill, it requires full wetting to the wall all the way around, as well as to the lead. However the solder does not need to come up onto the pad, it just has to be wetted to the wall and lead and not have a negative wetting angle.
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: Wednesday, March 16, 2016 4:27 PM
To: [log in to unmask]
Subject: Re: [DC] Hole Fill and Thermal Relief
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?
On Wed, Mar 16, 2016 at 2:35 PM, Guy Ramsey <[log in to unmask]> wrote:
> The standard requires the solder be wetted to the lead and the PTH.
> On Mar 16, 2016 3:30 PM, "Jack Olson" <[log in to unmask]> wrote:
>
>> I posted this to IPC TechNet, but I think many people are busy at
>> APEX this
>> week:
>>
>> -=-=-=-
>>
>> 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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