Joel

Now we know you are using a UV curable, you should check the curing  
set-up with the coating manufacturer. Seems like too much energy...

Kindest regards,

Graham

[log in to unmask]



On 24 Apr 2007, at 15:12, Joel Alexander wrote:

> The application is very tight with many close keep out areas. That  
> is why
> we are using a precision coating machine with a UV cure. The boards  
> area
> cured seconds after that are coated so the coating does not spread out
> onto keep out areas.  This is new equipment and the manufacturer has
> resolved the bubble problem but we now have to determine what to do  
> with
> the product that is already coated.
>
>
>
> Joel Alexander
> Quality Assurance Manager
> TT APSCO, INC.
>
> ----- Forwarded by Joel Alexander/perry/apscoinc on 04/24/2007  
> 10:05 AM
> -----
>
> "Bloomquist, Ken" <[log in to unmask]>
> Sent by: TechNet <[log in to unmask]>
> 04/24/2007 09:24 AM
>
> Please respond to
> TechNet E-Mail Forum <[log in to unmask]>; Please respond to
> "Bloomquist, Ken" <[log in to unmask]>
>
>
> To
> [log in to unmask]
> cc
>
> Subject
> Re: [TN] Conformal  Coating Voids
>
>
>
>
>
>
> Joel,
>
> We use a moisture cure urethane and if we get the coating on too thick
> and the humidity is high we get foam like bubbles. I believe the  
> coating
> skins over too fast trapping all the volatiles underneath. We resolved
> this by doing a 40% first coat and then a 60% second coat to get the
> required thickness. We only allow about 20 - 30 minutes between coats.
> And like Ramon said, don't put them in an oven too soon after  
> coating if
> you oven dry your boards.
>
> KennyB
>
> -----Original Message-----
> From: BADRI [mailto:[log in to unmask]]
> Sent: Tuesday, April 24, 2007 6:15 AM
> To: [log in to unmask]
> Subject: Re: [TN] Conformal Coating Voids
>
>
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Joel Alexander
>> Sent: den 23 april 2007 21:47
>> To: [log in to unmask]
>> Subject: [TN] Conformal Coating Voids
>>
>> We are using Urethane coating on an assembly that uses  63/37 solder.
>> We are using organic water soluble flux. We are Ionic testing after
>> wash and we are well within IPC cleanliness specifications. We
>> installed a selective coating machine and in our initial run of
>> product we had some small bubbles that look like foam. Our customer
>> does not like it but our stand is that it meets IPC-A-610 and
>> J-STD-001 requirements since there in no obvious voids between
>> conductors. They were worried about corrosion if a bubble was against
>> a lead. The bubbles are fully encapsulated. Does anyone think this is
> a valid concern?
>>
>>
>>
>> Joel Alexander
>> Quality Assurance Manager
>> TT APSCO, INC.
>>
>>
>
> ForwardSourceID:NT000B42FA
>
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