I missed the beginning of this exchange due to my trying to upgrade
computer, software and ISP all at the same time [and managed to achieve my
new antivirus software intercepting the new system health checking software
and crashing the computer - there's irony for you], so my apologies if I
duplicate responses already made.
Contrary to marketing blandishments a large number of UV cured applications
actually turn out in practise to be dual cure, this sounds a reasonably high
probability of being one.
In the reality of production what actually happens is that the UV is used as
a quick tack, and final cure is accomplished thermally. In this SMT adhesive
application it is possible, maybe intended, that the subsequent soldering
operation will give sufficient thermal input to finish off the cure, but I
would recommend that this is actually verified by testing using worst case
scenarios. ie large deposits in the centre of large area devices.
Mike
-----Original Message-----
From: Graham Naisbitt <[log in to unmask]>
To: Michael Fenner <[log in to unmask]>
Date: 23 June 1999 14:29
Subject: Fw: [TN] Epoxy
>
>Regards,
>Graham Naisbitt
>
>[log in to unmask]
>
>Concoat Ltd
>Alasan House, Albany Park
>CAMBERLEY GU15 2PL UK
>
>Tel: +44 (0) 1276 691100 Fax: +44 (0) 1276 691227
>----- Original Message -----
>From: Graham Naisbitt <[log in to unmask]>
>To: TechNet E-Mail Forum. <[log in to unmask]>; joyce <[log in to unmask]>
>Sent: Wednesday, June 23, 1999 2:20 PM
>Subject: Re: [TN] Epoxy
>
>
>> Joyce et al,
>>
>> Very interesting. One other observation is that we have measured many
>> standard UV epoxy coatings and found that the uncured material in the
>> shadowed areas was 10000 times more conductive than the exposed/cured
>> material.
>>
>> Regards,
>> Graham Naisbitt
>>
>> [log in to unmask]
>>
>> Concoat Ltd
>> Alasan House, Albany Park
>> CAMBERLEY GU15 2PL UK
>>
>> Tel: +44 (0) 1276 691100 Fax: +44 (0) 1276 691227
>> ----- Original Message -----
>> From: joyce <[log in to unmask]>
>> To: TechNet E-Mail Forum. <[log in to unmask]>; Graham Naisbitt
>> <[log in to unmask]>
>> Sent: Tuesday, June 22, 1999 1:45 AM
>> Subject: Re: [TN] Epoxy
>>
>>
>> > I saw a demo few weeks ago. The trick is to use a hand held UV point
>> source
>> > positioned at (almost) glazing angle to the PWB (maximum exposure to
the
>> > adhesive) to get under the components. The unit may have reflective
>> mirrors
>> > to reflect the light in different angles... It took 10 - 15 sec to cure
>> the
>> > adhesive. I have little concern about the un-exposed photo-activators.
>> > These un-exposed photo-activators will cause instability of the
material
>> if
>> > it is not passivated by either thermal cure or other method. (based on
>my
>> > out dated knowledge, the excess photo-activators were normally used to
>> > ensure the material reach the full cure easily. If anyone have updated
>> > infor. please let me know).
>> > My 2 cents.
>> > jk
>> > At 01:08 PM 6/21/99 +0100, you wrote:
>> > >Iain and other TechNetters
>> > >
>> > >Forgive my ignorance but is there such a material?
>> > >
>> > >I would have thought that a UV adhesive couldn't be used in such an
>> > >application unless you can bend light to get under the component and
>> react
>> > >the photo-initiator.
>> > >
>> > >I thought bending light was tricky so if there are such things, I have
>> some
>> > >applications in mind so would love to hear from the experts.
>> > >
>> > >Regards,
>> > >Graham Naisbitt
>> > >
>> > >[log in to unmask]
>> > >
>> > >Concoat Ltd
>> > >Alasan House, Albany Park
>> > >CAMBERLEY GU15 2PL UK
>> > >
>> > >Tel: +44 (0) 1276 691100 Fax: +44 (0) 1276 691227
>> > ><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
>> > ><HTML><HEAD>
>> > ><META content="text/html; charset=iso-8859-1" http-equiv=Content-Type>
>> > ><META content="MSHTML 5.00.2314.1000" name=GENERATOR>
>> > ><STYLE></STYLE>
>> > ></HEAD>
>> > ><BODY bgColor=#ffffff>
>> > ><DIV><FONT size=2>Iain and other TechNetters<BR><BR>Forgive my
>ignorance
>> > but is
>> > >there such a material?<BR><BR>I would have thought that a UV adhesive
>> couldn't
>> > >be used in such an<BR>application unless you can bend light to get
>under
>> the
>> > >component and react<BR>the photo-initiator.<BR><BR>I thought bending
>> light was
>> > >tricky so if there are such things, I have some<BR>applications in
mind
>> so
>> > would
>> > >love to hear from the experts.<BR></FONT></DIV>
>> > ><DIV><FONT size=2>Regards,<BR>Graham Naisbitt</FONT></DIV>
>> > ><DIV> </DIV>
>> > ><DIV><FONT size=2><A
>> >
>>
>>href="mailto:[log in to unmask]">[log in to unmask]<
/
>> > A></FONT></DIV>
>> > ><DIV> </DIV>
>> > ><DIV><FONT size=2>Concoat Ltd<BR>Alasan House, Albany
Park<BR>CAMBERLEY
>> > GU15 2PL
>> > >UK</FONT></DIV>
>> > ><DIV> </DIV>
>> > ><DIV><FONT size=2>Tel: +44 (0) 1276 691100 Fax: +44 (0) 1276
>> > >691227</FONT></DIV></BODY></HTML>
>> > >
>> >
>> >
>>
>
>
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