We experienced the same issue. Implemented a 30 minute room temperature gel time prior to UV cure fixed the issue. I understand this may not always be preferable, but it works. I tried a pre-heat function prior to UV cure, that seemed to make the edge-peeling worse instead of better.
But Joyce is absolutely correct, the surface must be super clean and free of humidity; super dry. We use a DR Storage drybox for cuing up the CCAs to be bonded. Do not allow more than 1 hour of exposure to humidty between the final cleaning, bake, and entry in the drybox. Minimize the time from removal from the drybox to bonding application.
-----Original Message-----
From: TechNet <[log in to unmask]> On Behalf Of Yuan-chia Joyce Koo
Sent: Wednesday, January 13, 2021 10:58 AM
To: [log in to unmask]
Subject: Re: [TN] [External] [TN] Latex Masking Material for Conformal Coating
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in general - edge lifting due to possible following (1) floor life exceeding allowable between the process - usually happened when the
clean room is boarder line on "clean" - reduce allowable floor life.
(2) residue on the surface of the coated surface and (3) viscosity too high - surface tension pull back the coating before UV hits - either due to non-uniform mixing or at end of the batch (solvent evaporated). Of course there are many other possible causes, but all the above can be eliminated if someone pay attention to control process and leave some safety margin (not push to the limit. e.g. I will never use batch at end of its shelf life, 70% is my sleep sound bench mark... sure you can extend the shelf life, but you need to do testing on properties, surface tension, solid content, share ratio,
etc.etc. the cost usually didn't show on MGR desk, but 100% of the
time is more than the batch - except special materials. plus the risk you take on possible issue you didn't test - you never can test it fully at cost as coating MFG for sure).
my 1.4 cents.
jk
On Jan 13, 2021, at 8:38 AM, Richard Kraszewski wrote:
> We don't use enough UV masking to give you a solid opinion.
> I assume what you are seeing may be related to shrinkage.
>
> Rich Kraszewski
> Senior Staff Process Engineer
>
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> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of lduso - Diamond-
> MT.com
> Sent: Friday, January 8, 2021 9:17 AM
> To: [log in to unmask]
> Subject: Re: [TN] [External] [TN] Latex Masking Material for Conformal
> Coating
>
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>
> Have you ever had any issues with the UV cure lifting slightly from a
> flat surface and allowing some creepage under? I had it happen a
> couple times but for the most part no issues.
>
> Lloyd Duso
> Diamond-MT
> (814) 535-3505
> www.Diamond-mt.com
>
>
> On Fri, Jan 8, 2021 at 10:07 AM Douglas Pauls < 0000000b68b3b1cd-
> [log in to unmask]> wrote:
>
>> Good morning Rich,
>> We have used the following with good success.
>> Kester Wondermask P - heat curable
>> Dymax Emax 906B and Dymax 9-20515 - UV curable masks. The 906B is
>> blue and thicker. The other is red and thinner.
>> Loctite AS8998 hot melt masking agent.
>>
>> ---
>> *Douglas Pauls *| Principal Materials and Process Engr | Advanced
>> Operations Engineering
>>
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>>
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>> *Tel:* +1 319 295 2109 | *Mobile: *+1 319 431 3773
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>>
>> On Fri, Jan 8, 2021 at 8:53 AM Richard Kraszewski <
>> [log in to unmask]> wrote:
>>
>>> Our preferred "non-ammoniated" liquid masking material for coating
>>> is on back order.
>>> I need to find another product.
>>> Can anyone please share which masking they have good success with?
>>>
>>> Rich Kraszewski
>>> Senior Staff Process Engineer
>>> Phone: (920) 969-6075
>>>
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>>> and any attachments are confidential from Plexus Corp. and
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>> by
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