Al,
I agree with other comments that it shouldn't be too difficult to
demonstrate joint reliability with destructive testing, but if your
customers are like some I know, they my think that the letter of the
spec is the only definition of acceptability. If so, we have improved
heavy board solderability by pre-heating to around 200'F just before
placing on the solder conveyor. This is not very handy 'cause the part
is so hot, but it may get you over the hump.
Ralph Vaughan
Boeing-Atlanta
> ----------
> From: McMonagle, Michael R.[SMTP:[log in to unmask]]
> Reply To: TechNet E-Mail Forum.;McMonagle, Michael R.
> Sent: Friday, June 26, 1998 1:22 PM
> To: [log in to unmask]
> Subject: Re: [TN] Thru-hole Reliability
>
> If you have already done everything you can with wave parameters such
> as
> preheat/speed/dwell/flux activity you now have a quandry with quality
> assurance and possibly end users. You may want to approach it from the
> same way you would prove integrity of an intrusive reflow/pin in paste
> connection. If you cannot achieve acceptable volume per industry spec,
> you need to assure quality/engineering/customer of a robust
> physical/electrical connection. Begin by cross sectioning a variety of
> connections on a few boards to get real average expected volume
> measurements under your existing process and to show
> consistency/repeatability. It will also show that the joint, though
> minimal, has no hidden voids which would further reduce volume. You
> can
> then take non-cross sectioned joints from the same boards and perform
> pull testing to demonstrate physical integrity. Pull testing will
> normally prove that either the pin breaks before the joint, or the
> whole
> barrel will come out of the board with the pin. Rarely (I have never
> seen) will the solder joint itself fail. Best of luck....
>
> > -----Original Message-----
> > From: Alan Kreplick [SMTP:[log in to unmask]]
> > Sent: Friday, June 26, 1998 9:42 AM
> > To: [log in to unmask]
> > Subject: [TN] Thru-hole Reliability
> >
> > I have a board that is .250" thick with 34 layers with 1 and 2 oz.
> > copper. I
> > have been able to achieve a 25-50% hole fill both by hand and wave
> > soldering.
> > The only component that is being soldered are sixty-four tantalum
> > capacitors
> > (assembled with a partial clinch).
> >
> > We normally follow IPC's 75% hole fill guideline.
> >
> > Is the solder connection reliable both electrically and mechanically
> > (we build
> > ATE products that do not require thermal cycles or vibration tests)?
> >
> > Is 25-50% of .250 (.062"-.125") hole fill more reliable than a 75%
> > hole fill on
> > a .060" board (.045 hole fill)? I've used this argument to say that
> > it is more
> > reliable even though it does not meet the 75% hole fill criteria.
> >
> >
> > Thanks for any help,
> >
> >
> > Al Kreplick
> > Sr. Mfg. Eng.
> > Teradyne, Inc.
> > 617-422-3726
> >
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