Jack,
Your question is difficult to answer because it relates to terms different
people use. Historically the difference (last 15 years or so) between
silkscreen and soldermask is silkscreen is nomenclature marking on PWBs
and solder mask is the dielectric covering the circuits. Simply stated
that is usually the difference between the two terms.
Hope this helps!
Regards,
Bob Metcalf
Western Regional Manager
Atotech USA Inc
1750 Overview Drive
Rock Hill, South Carolina 29730 USA
Mobile: 714-334-7667
e-mail: [log in to unmask]
Internet: www.atotech.com
Managing Director: Kuldip Johal
This e-mail and any attachments hereto are business documents of Atotech
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From: Jack Olson <[log in to unmask]>
To: <[log in to unmask]>
Date: 08/09/2011 07:04 AM
Subject: Re: [TN] White SolderMask
Sent by: TechNet <[log in to unmask]>
Thanks everyone, for taking the time to respond.
That was a new one for me.
(its interesting what I take for granted until something goes wrong!)
one more question:
Is there a difference between soldermask material and silkscreen material?
Aren't they both just colored epoxies?
(ok, two questions!)
Jack
.
On Mon, 8 Aug 2011 08:51:36 -0700, Bob METCALF <[log in to unmask]>
wrote:
>White mask historically has performed different than it's green
>counterpart. Depending on the pigment used to make it white, it can have
>an affect on cure, but also the initial exposure step that created the
>image (I'm assuming we are talking about a liquid photoimagable solder
>mask). If the UV light does not cross link the mask enough in the initial
>exposure step the developer will "attack" the mask more in the
development
>stage and diminish performance during the assemble process.
>
>In addition to insuring the proper curing steps are observed, which could
>include a UV cure, I would make sure they are tack drying and exposing
the
>white mask to the manufactures recommendations. If the fabricator is
>simply using the same steps used to process green mask, this could be
>creating your problem.
>
>Regards,
>
>Bob Metcalf
>Western Regional Manager
>
>Atotech USA Inc
>1750 Overview Drive
>Rock Hill, South Carolina 29730 USA
>
>Mobile: 714-334-7667
>e-mail: [log in to unmask]
>Internet: www.atotech.com
>
>Managing Director: Kuldip Johal
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
>Sent: Monday, August 08, 2011 7:47 AM
>To: [log in to unmask]
>Subject: [TN] White SolderMask
>
>Greetings,
>
>Have any of you experienced mask problems like the ones shown in these
>pictures?
>
>http://frontdoor.biz/PCBportal/WhiteMask.jpg
>
>The bottom picture shows exposed copper, and I believe there is a copper
>plane on the top layer.
>(this has happened to different boards, different lot codes, but MIGHT be
>the same batch of mask)
>
>What I'm wondering is, is it more likely that the problem is related to
>the
>fact that the mask is WHITE, or that it is some other problem?
>If the properties of white mask are different, maybe it doesn't adhere as
>well to the surface? I remember back in the olden days they used to ask
us
>to break up solid copper planes so the mask would stick better to the
>laminate, but I haven't heard of anyone having problems with that for a
>long
>time.
>
>The supplier said they baked some bare boards and ran them through the
>oven,
>and the problem went away, but we are reluctant to just blindly add a
>permanent baking step if there are other considerations.
>
>Jack
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