I read the 240 -270 span as being guidance to the range in which the process can be
expected to be done, so in other words when you determine an optimum temperature it will
be somewhere in that range. Having done so you still need to have process control of plus
minus x.
In a perfect world: The operating temp would be determined by optimising setup to achieve
best yields for your inspection criteria, and maximum permitted deviation by how far you
can go with out losing your yield.
This might be different by job type according to criticality of lay out fine fitch etc.
Or you can be a little more pragmatic in the real world by surveying a knowledge pool like
Technet and write that in.
Also in the real world you can only inspect for and make what you can actually do. If your
machine only holds say plus minus 10 or your measurement technique has an inbuilt
sensistivty of plus minus 5, there ain't no point in the Quality people writing plus
minus 2, however desirable that might be, as this means you have to shut the shop.
Mike Fenner
Bonding Services & Products
T: +44 1295 722992
F: +44 1295 720937
----- Original Message -----
From: Paul Klasek <[log in to unmask]>
To: <[log in to unmask]>
Sent: 07 October 1999 07:15
Subject: Re: [TN] Wave solder pot temperatures...
> Hmmm, Eric, it's not quite like it ; I'd doubt good ol' KW would mean the
> sensible span of alloy applicability doubling at the same time as tolerance
> window of your process .
> To hit 270 straps can be interesting exercise if you did not design for it .
> After all, pot check is not for the sake of the pot , but the boards ; and
> they come like us (allsorts) .
> Some like it cool, some hot. +/- , naturlich .
>
> paul klasek
> ResMed
>
> -----Original Message-----
> From: Eric Kalgren [mailto:[log in to unmask]]
> Sent: Thursday, 7 October 1999 7:32
> To: [log in to unmask]
> Subject: Re: [TN] Wave solder pot temperatures...
>
>
> Steve,
> We used to have a Hollis Future 1 and we kept the solder temp at 500 degF
> and ran just like that.
>
> My Klein-Wassink book says that for "most machine processes the temperature
> of the solder bath must be chosen between 240 and 270 degC and the dwell
> time between 2 and 4 seconds."
>
> Would this be a good enough justification to discontinue checking the solder
> temp as the book gives a 30 deg C tolerence? After all, when I asked the
> TechNet, the response was overwhelming that K-W was a good source.
>
> Eric Kalgren
> BFGoodrich Aerospace
> Data Systems Division
> (505) 938-5139
>
>
> >>> Hinners Hans Civ WRALC/LYPME <[log in to unmask]> 10/06/99
> 01:38PM >>>
> Hey Steve,
>
> Ideally, the temperature should be measured in the same location as the
> Hollis' thermocouple. That's how you verify the machines' temperature
> reading. Doesn't sound like she understands thermodynamics. I've got
> Kittel (Stat. Thermo) and a really great book by Fermi (Notes on Thermo) if
> you'd like to borrow it. :-) Who ever came up with that procedure needs a
> refresher.
>
> 1). Ask for a copy of their written calibration procedure and get the
> bloody thing changed! Then it will be the way they do things.
>
> 2). Is the handheld unit calibrated?
>
> 3). Is there training & certification for this inspection?
>
> 4). How long was the probe in the solder? Did the probe reach equilibrium?
> (That's what killed the Challenger Shuttle, in part.)
>
> I feel for ya bud. Remember, if engineering were easy everybody would do
> it. ;-)
>
> Hans
>
> PS. This crisis calls for Starbucks! (Okay, I'm Jonesing for a Venti
> Hazelnut Mocha.)
>
> ~~~~~~~~
> Hans M. Hinners WR-ALC/LYPME Bldg. 640
> Materials Engineer 380 Second Street,
> Suite 104
> Manufacturing Eng. Sec. Robins AFB GA 31098-1638
> 912-926-1970 (Voice) 468 - 1970 (DSN) 912-926-7974 (Fax)
> mailto:[log in to unmask]
>
>
>
> > It's been a frustrating day...
> >
> > I was at our old wave solder machine this morning (a Hollis SMT Future-1,
> > about 12-years old) and one of our QA inspectors came in to check the
> > calibration on it. The procedure here is to verify that the speed of the
> > belt
> > is what's indicated on the readout of the machine, and to check that the
> > solder temperature in the pot is within +/- 5 degrees F (which seems
> > unnecessarily tight to me). from what is indicated. I run my pots a
> > 485-degrees F. We were in the middle of a run, so she said that she'll do
> > the
> > belt speed check after we were through, but would go ahead and check the
> > solder temperature. We had the laminar pump running and she put the
> > thermocouple in the wave. The readout on the machine was 484 F., and she
> > indicated 490 F. on the hand held unit she was measuring with. She said;
> > "The
> > machine is out of calibration, your temperature is 6-degrees too high, it
> > needs to be re-cal'ed.." I told her it wasn't, that she should wait until
> > we
> > finish the boards we were waving so I could shut the pumps off, let the
> > pot
> > stabilize, and then she could take a reading. Her reply was (which I'm
> > getting so sick of); "That's not the way we do it around here..." ARRRRG!
> > No
> > matter how much I tried to explain about the solder being pumped up to the
> > top to the wave formers and cooling down flowing back into the pot, then
> > the
> > thermocouple in the pot sensing this, turning the heaters on to maintain
> > the
> > set temperature and that's why the reading was a little high, I couldn't
> > get
> > through to her...so I gave up.
> >
> > But what's a realistic slop factor as far as the indicated temperature and
> > actual temperature of the solder. I think +/- 5-degrees F is way to tight,
> > I
> > was thinking more like +/- 15-degrees....any opinions?
> >
> > Thanks!
> >
> > -Steve Gregory-
> >
> > P.S. anybody need a good engineer?
> >
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