Hey, don't forget that in the civilised world, an eraser is called a
rubber. In fact that's how caoutchouc got its name, because it was first
used for rubbing out mistakes when writing. Nothing to do with friction
between men and women, even when they live in condominiums!
Brian
David D. Hillman wrote:
> Hi Mike, Brian and gang! I'll go chase down Brian's InterNepcon '69 paper
> and the book chapter segment. Our Rockwell Collin's Technical Reference
> database is pretty extensive but I was striking out on this one. I haven't
> heard back from ITRI yet and was getting impatient so I thought I would
> ask TechNet for help. The reason I am chasing that reference is that I
> have finally gotten feed up with addressing the issue of well intended but
> misguided internal/external customers using "Pearl Pink" erasers as a
> surface finish oxide/discoloration removal protocol. The pink erasers come
> from multiple sources, have uncharacterized chemical compositions and
> leave contamination on the printed board surfaces that have been
> "cleaned". My co-op students and I have completed a small investigation
> demonstrating the issues using SEM and FTIR results on a variety of
> printed wiring board surface finishes and now I am just pulling together
> the external data sets on the topic that other investigators have
> published. Oddly, it seems to be a topic that everyone fully understood in
> the late '60s but has been erased (what a pun!) from the industry tribal
> knowledge pool. The pumice and ScotchBrite information has been captured
> in the external data sets as well so I am going to include that
> information in the our paper. Probably something that I'll publish at one
> of the IPC or SMTA conferences. Looks like I'll be giving the TechNet an
> acknowledgement for everyone's most valuable assistance! Thanks to
> everyone for their assistance - TechNet is such a great tool!
>
> Dave
>
>
>
> Mike Fenner <[log in to unmask]>
> Sent by: TechNet <[log in to unmask]>
> 02/06/2009 06:04 AM
> Please respond to
> [log in to unmask]
>
>
> To
> [log in to unmask]
> cc
>
> Subject
> Re: [TN] In Search of a Technical Reference
>
>
>
>
>
>
> I remember Colin Thwaites's paper very well and Brian's, was grateful for
> them, but no longer have copies.
> I would be surprised if the ITRI people don't find a copy. I asked them
> for
> an actual reference to some information of the industry legend type -
> meaning everyone knows it but not why or how they know it - and they found
> first references in early 1940s.
>
> Regards
>
>
> Mike
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
> Sent: Friday, February 06, 2009 7:30 AM
> To: [log in to unmask]
> Subject: Re: [TN] In Search of a Technical Reference
>
> Dave
>
> I hadn't realised that Colin Thwaites had published such a paper. I
> believe that his research of the subject may have been instigated by
> myself, following publication of the paper I presented at Inter/Nepcon
> '69, in Brighton, England, 'New Aspects on the Solderability of Printed
> Circuits'. Unfortunately, I no longer have a copy of the Technical
> Proceedings but, as I remember it (40 years is a long time ago!!!), I
> evoked the problems caused by both pumice and ScotchBrite cleaning,
> whereby the abrasive particles were embedded into the copper pore
> structure and then the copper was swaged over them. The only way they
> could be released was with a light persulfate etch and forceful rinse,
> without which dewetting was inevitable after abrasive cleaning.
>
> Having written this, I then re-read what I wrote in Section 7.2.4 (p.
> 76) of my book and found that it's similar in essence but more complete,
> so my aged memory can't be that bad! Whatever, abrasives and
> solderability make poor bedmates!
>
> Hope this helps.
>
> Brian
>
> David D. Hillman wrote:
>> Hi gang! Ok, I am in search of a technical reference and my usual,
> "always
>
>> works" sources have failed me. I am looking for the following technical
>> reference:
>>
>> Thwaites, C. J. and Mackay, C. A. , " Some Effects of Abrasive Cleaning
> on
>
>> the Solderability of Printed Circuits", Metal Finishing Journal, Sept.
>> 1968, pp. 291-294, (also may be listed as ITRI Publication 386)
>>
>>
>> Anyone have a copy or can direct me to where a copy can be obtained? And
>
>> yes, I have sent a request to the ITRI folks already (International Tin
>> Research Institute)
>>
>> Dave Hillman
>> Rockwell Collins
>> [log in to unmask]
>>
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