Sorry, Steve, just the same one but I have a few new signed copies left, 
complete with annotated PDF update file.

Brian

On 23.05.2013 19:33, Steve Gregory wrote:
> Hi Brian,
>
> You have a new one in publication? Where can I get it?
>
> Steve
>
> -----Original Message-----
> From: Brian Ellis [mailto:[log in to unmask]]
> Sent: Thursday, May 23, 2013 10:30 AM
> To: TechNet E-Mail Forum; Steve Gregory
> Subject: Re: [TN] White Residue Disappears with heat gun, what does that mean?
>
> You will then want a new, signed, copy! :D
>
> Brian
>
> On 23.05.2013 19:13, Steve Gregory wrote:
>> Hi Mike,
>>
>> Unfortunately a lot of what we build here is consigned
>> stuff...customer supplied boards and parts. So often times I won't
>> even know who built the fabs.
>>
>> One of the questions I have is; by using the heat gun am I actually
>> curing the mask? Why doesn't that happen during reflow or wave solder?
>>
>> Brian,
>>
>> Guess what? I found a used copy of your book on Amazon that I'm buying.
>> It should arrive in 2-3 weeks. It will be one that I'm going to
>> study....
>>
>>
>> Steve
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Mike Fenner
>> Sent: Thursday, May 23, 2013 3:34 AM
>> To: [log in to unmask]
>> Subject: Re: [TN] White Residue Disappears with heat gun, what does
>> that mean?
>>
>> I agree it probably is under cured resist, but as Brian says it may
>> not be.
>> If you were using a no clean and had this the explanation could be
>> unremoved resin which is melting back to its normal translucent state,
>> the white would be analogous to the water mark left by a coffee (tea
>> for
>> me) cup on a polished table. Probably not too bad a risk. The downside
>> with unremoved water soluble flux residues is much higher. You need to
>> be more certain. So you have done a simple test and have an
>> indicative, but not absolute result.
>> So you need to do some more work.
>> If it is under cured resist then boards from a different batch may not
>> show it, so all else being the same it's your board supplier's problem.
>> You could also try finishing off the cure by baking some unpopulated
>> boards for say a couple of hours at 100C. If it goes away on the baked
>> boards, but not on unbaked boards then it's your PCB suppliers problem.
>> Meanwhile you have a keep you going fix till the problem is rectified.
>> Another thought is - has PCB supplier changed the resist in some way,
>> if it is now shinier than before this may be highlighting an existing
>> problem.
>> So you could also contact your PCB supplier outline the problem,
>> ignore the never had that before etc, ask them to collaborate with you
>> to identify the problem by elimination all possible causes.
>> Anyway their contribution in the elimination process would be to
>> supply a batch which is definitely cured and do another side by side
>> test. No doubt you already doing that though.
>>
>> Best Wishes
>>
>>
>>
>> Mike
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
>> Sent: Thursday, May 23, 2013 7:38 AM
>> To: [log in to unmask]
>> Subject: Re: [TN] White Residue Disappears with heat gun, what does
>> that mean?
>>
>> There are a number of potential causes. A common one is the exposure
>> of solder mask fillers because the cleaning removes the surface
>> molecules of the solder mask. This is largely cosmetic but it may mean
>> the mask is insufficiently cured. As you state (or I did in the
>> earlier exchange!), heat will allow the filler to sink in.
>>
>> Another common cause is that a resin (synthetic or rosin) or
>> carboxylic activator from the flux has spread and hydrolysed. This
>> indicates a potential incompatibility of the flux and cleaning
>> chemistries. This was common in the days of cleaning DIN 8511 F-SW32
>> type fluxes in CFC-113 azeotropes, as well as aqueous cleaning of many
>> modern fluxes. The residues, which are not necessarily ionic, may form
>> a hydrogen bond to low MW components of the solder mask whose surface
>> may be incompletely polymerised.
>>
>> There are five pages devoted to these phenomena described in more
>> detail in my book from p. 157 ff.
>>
>> You should determine the cause and take measures to eliminate it,
>> rather than work in the dark. This means a series of systematic
>> diagnostic tests and can be a painful process because you may have
>> combinations of up to about half-a-dozen contributory factors, some of
>> which may require expensive analyses. Empirical trial-and-error is usually unsatisfactory.
>>
>> Hope this helps.
>>
>> Brian
>>
>>
>> On 23.05.2013 02:37, Steve Gregory wrote:
>>> Hi all,
>>>
>>>
>>>
>>> I know we've talked about this before, but I seem to forget the fine
>> details lately. (blame it on me getting old or something),
>>>
>>>
>>>
>>> Anyways, we've got a different (newer)cleaner and we've just gotten
>>> it
>> going over the last few days. The cleaner is close-looped which is
>> different than the way the old cleaner operated. Had a little foaming
>> issue that was solved by putting in another carbon bed. But today I
>> washed a board after it had come off the wave, and the bottom surface
>> of the board had what I call "Zebra Stripes" of what looked like white
>> residue along the bottom of the board. They are pretty much shadows of
>> the conveyer mesh chain that the board was sitting on through the
>> cleaner:
>>>
>>>
>>>
>>> http://stevezeva.homestead.com/ZebraStripes.jpg
>>>
>>>
>>>
>>> I ran the board through the Omegameter we have and of course it
>>> passed
>>
>>> at
>> 4.3 ?g NaCl/sq. in.. I took the board out of the Omegameter tank and
>> the stripes were gone, which didn't puzzle me too much. Boards always
>> seem to come sparkly clean out of an Omegameter tank.
>>>
>>>
>>>
>>> I ran the board through the cleaner again and the white stripes
>> re-appeared. Our cleaner is a Austin America Microjet, our water is at
>> 13 megohm, I'm running 135 F. in my wash at a belt speed of 2 fpm. My
>> dry section is 100 F. We're using a Indium 1095 water soluble flux in
>> a foam fluxer in our wave.
>>>
>>>
>>>
>>> I remembered something from the TechNet a long time ago about heating
>>> the
>> board with a heat gun to see if the white residue disappears. I
>> searched the archives and found this from Bill Kenyon:
>>>
>>>
>>>
>>> "Quick identification of the (solder mask) residue- if it is the
>>> white
>> powder fumed silica used to thicken liquid solder masks, you will
>> often see it appear as Brian has noted. If the solder mask is
>> undercured, any cleaning step may strip off part of the green solder
>> mask, exposing the white thickener powder (typical trade name is
>> 'Cab-O-Sil"). Heat the white area with a heat gun. If the residue is
>> the Cab-O-Sil, the heat softened solder mask will allow the Cab-O-Sil
>> to sink back into the green solder mask.
>> Residue disappears, problem is insufficient UV cure during solder mask
>> processing."
>>>
>>> So I tried that, and the stripes disappeared. I cleared almost all of
>>> the
>> stripes with the heat gun and re-ran the board through the cleaner and
>> the stripes pretty much stayed gone...I can barely see a shadow of them.
>> The information that Bill Kenyon shared with us was from quite some
>> time ago, but that still applies, correct?
>>>
>>>
>>>
>>> Steve Gregory
>>>
>>>
>>>
>>>
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