Hi, John,

Your comment is comprehensive and helpful.  Concerning your suggested
Monoethanol Amine based stripper, is it perfectly applied for the aqueous
dry film we are currently using?

Secondly, do you recommend autodosing or batchwise replenishment still
fine.  By the way, when caustic soda stripper is used, the dry film is
detached from the board in strong alkali condition, not dissolved in it,
how about your recommended one?  I firstly apologize for the lengthy
questions but I eagerly to make everything clear at one time.


At 10:27 AM 4/10/99 -0400, Nelson, John wrote:
>Chris is right.  It is not a good idea to strip resist in caustic when there
>is solder or tin present.
>Most proprietary strippers contain Monoethanol Amine (70-80%) and 1,2
>Ethanediamine (5-10%)
>and trace amounts (1-5%) of anti-tarnish like Benzotriazole to keep the
>copper bright.  In a previous
>life we used generic Monoethanolamine as a resist stripper.  It can be a bit
>malodorous (smells like dead fish) but it gets the job done.
>
>The waste stripper is pH neutralized to precipitate out the resist and then
>treated for dissolved metals if necessary.  There should be much less
>dissolved metal than a caustic styripper because the amine based strippers
>do not remove as much metal from the boards.
>
>> -----Original Message-----
>> From:        Albert Mok [SMTP:[log in to unmask]]
>> Sent:        Saturday, April 10, 1999 6:44 AM
>> To:  [log in to unmask]
>> Subject:     [TN] Problem during strip dry film
>>
>> Dear team,
>>
>> We have problem during dry film stripping, which is the process just
>> before
>> etching.
>>
>> During the dry film stripping, two stages of dry film stripping processes
>> are used and some of the Tin(act as etch resist) seems dissolve a bit at
>> the bare copper area just after stripping when in contact with stripping
>> solution of caustic soda and result etching problem.  Especially for fine
>> spacing of 6-8mil, the incomplete etching problem are more serious and
>> sometimes re-etch the boards for twice again are required.
>>
>> Do anyone have any idea to resolve it?  The temperature employed is 40 C
>> and the conc. of NaOH is 150 g/L.
>>
>
>

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################