As Dana Carvey once said, " Well, Isn't that Special".

On Tue, Mar 29, 2022 at 10:48 AM Wayne Thayer <[log in to unmask]>
wrote:

> Hi Ben-
>
> Well said.
>
> I see an epidemic of poorly designed systems using these types of joints.
>
> As these "special" connections are now commonplace, perhaps it is time for
> IPC to update the butt joint section to include them. Or perhaps include
> their own section called "highly stressed solder joints". After all, that's
> the predominant engineering challenge with these things: (Pin-to-pad
> contact area) / (potential lever arm) is relatively small, especially when
> compared to the pin stiffness.
>
> Wayne Thayer
>
> On Mon, Mar 28, 2022 at 12:27 PM Gumpert, Ben <[log in to unmask]>
> wrote:
>
> > Wayne,
> >
> > Since J-STD-001 and IPC-A-610 describe what has traditionally been
> > considered a butt-joint as PTH parts that have been trimmed to the butt
> > configuration, and mentions new "versions" of a butt joint such as those
> > used in solder-charged connections, I see the termination shown in 8-180
> as
> > "different" from the butt joints that are not permitted. So they are
> > "special".
> >
> > I agree with you that "special" terminations need to have acceptance
> > criteria agreed to with the customer, so if that's done, then it wouldn't
> > matter if they were butt joints since that would imply that they are
> > documented in the engineering and therefore take precedence over the
> > J-STD-001/IPC-A-610. Unless you could convince yourself that other
> criteria
> > in the J-STD-001 is close enough to be applicable (they are kind of
> > butt-joints so that the butt joint criteria applies, but not really
> > butt-joints so the prohibition doesn't? lol)
> >
> >
> > Ben Gumpert
> >
> >
> > -----Original Message-----
> > From: TechNet <[log in to unmask]> On Behalf Of Wayne Thayer
> > Sent: Saturday, March 26, 2022 11:18 AM
> > To: [log in to unmask]
> > Subject: EXTERNAL: [TN] Specialized Connections
> >
> > Over the last 15 years there has been an explosion in the availability of
> > surface mount board-to-board connections. Some of these use traditional
> > folded pins, but more and more are using stamped pins with no stress
> > limiting bends in the connection.
> >
> > Photo 8-181 in IPC-A-610H Section 8.4 is an example of this.
> >
> > Can someone explain to me why IPC calls these "special" as opposed to
> what
> > they are: butt joints? I have a module supplier who claims the butt joint
> > requirements don't apply because they are "special". Thus, whereas butt
> > joints are dis-allowed in Class 3 and must not overhang the pad for Class
> > 2, this module supplier claims they are fine. No doubt the "butt joint"
> > section of 610 should be updated to explicitly show this type of
> > termination, but anyone who categorizes soldered interconnects would have
> > to label these as common butt joints (where the metal is sheared out of
> > whatever stock it is made from and then soldered with the sheared side
> > against the pad.
> >
> > If there were only a few of these types of connectors on the market, or
> if
> > they were seldom used, the "special" would be a valid term. But today
> > industrial PCBAs I see more commonly have these than not.
> >
> > (And yes, a supplier who uses the "special" clause still isn't out of the
> > "hot seat" because they are supposed to bring this up with the customer
> > when they accept the job.)
> >
> > By the way, another photograph in Section 8.4, 8-180, shows a standard
> > surface mount dual row header (which is made up of pins bent into an "L"
> > shape) with a surface mount to through hole adapter installed. What makes
> > that "special"? The fact it has something plugged into it? So if it
> leaves
> > the assembly plant without that adapter installed, it wouldn't become
> > "special" until a user plugged in that adapter socket?
> >
> > Thanks!
> >
> > Wayne Thayer
> >
>