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February 2004

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Subject:
From:
"Sklenar Vit (RBAU-AE/MFE4) *" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 3 Feb 2004 16:01:04 +1100
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Hi all, 

interesting communication on this issue - Matte vs Gloss. Apart from the solder balling issue , we found that the matte
solder mask could be more susceptible to the effect of washing detergent residues after washing when entrapped underneath of relays or other parts. This affected SIR, or reaction with copper when penetrated solder mask later on and could cause field failure. Anybody had a similar experience?

Vit Sklenar
Process Eng
Robert Bosch Australia 

-----Original Message-----
From: Dale Ritzen [mailto:[log in to unmask]]
Sent: Tuesday, 3 February 2004 12:05 AM
To: [log in to unmask]
Subject: Re: [TN] Matte vs. Gloss Finish for Solder Mask


David , Carrie, et al,

The only experiment we ever did with a matte finish PCB turned out badly. We
had been seeing solder balls after the solder wave on a legacy product (no
SMT, just PTH parts) and were having trouble getting a conformal coat to
adhere properly to the gloss solder resist on the board. We decided that the
matte finish would help in both cases. When we went to a "very matte"
finish, we lost the solder balls, but gained solder webbing like I've never
seen before! So, we went back up to a semi-gloss solder resist and were back
in business.

Whatever finish you choose, you MUST see what the result is and make your
final choice accordingly. It's the same with any process change you make.

Dale Ritzen, CQA
Quality Manager
Austin Manufacturing Services

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of David Hoover
Sent: Saturday, January 31, 2004 5:44 PM
To: [log in to unmask]
Subject: Re: [TN] Matte vs. Gloss Finish for Solder Mask


Carrie,

I remember some time (way) back where a SIC (SEC) test comparison
suggested that matte soldermask tended to yield higher numbers suggesting
potential flux residues (or something). I believe this would be due to the
additional surface area caused by the matte surface. This may not
necessarily
be applicable to all matte soldermasks. Just the ones that were ran in the
tests.
But it does bring up a valid subject on surface tensions associated with
surface
area. Someone who processes any kind of liquids, pastes, or inks may
encounter
some variation from the soldermask type.

I tend to agree with Mike's statement that most specify
"semi-matte/semi-gloss"
soldermask type. It's the best of both worlds.
Electrical Performance (Speed) is another topic for discussion.

Cheers,

See you all at IPC APEX/EXPO in Anaheim.

David Hoover  (aka, Groovy)

----- Original Message -----
From: "Barmuta, Mike" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, January 27, 2004 9:45 AM
Subject: Re: [TN] Matte vs. Gloss Finish for Solder Mask


> Carrie: First I am assuming your are asking about LPI soldermask only.
>
> From a board fabrication standpoint there should not be any additional
cost
> or processing steps. The major difference is in the formulation. So asking
> or specifying a matte mask should not effect the bare board cost.
>
> A full matte finish may be more susceptible to scratching depending on the
> filler system and amount of resin in the mask. It is also more prone to
> showing surface cosmetics and white haze/residue. Gloss finish boards do
not
> display this as much. However gloss soldermask can be hard to inspect, TU
> and manually load components due to it's high reflectivity.
>
> There is another issue and that is the electrical performance properties
of
> the mask. There are "some" matte masks that have reduced electrical
> properties than a gloss mask. This can be the result of higher filler
> content, less resin, etc. However there are many more things that play
into
> this than just the matte issue. The formulation, type and amount of resins
> and cure can also influence the electrical performance greatly. There are
> many matte masks that are comparable to non-matte types.
>
> Most people specify a semi-matte/semi-gloss as opposed to a full matte.
This
> provides a good compromise from the two ends of the spectrum.
>
>
> Regards
>
> Michael Barmuta
>
> Staff Engineer
>
> Fluke Corp.
>
> Everett WA
>
> 425-446-6076
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Morse, Carrie
> Sent: Tuesday, January 27, 2004 8:24 AM
> To: [log in to unmask]
> Subject: [TN] Matte vs. Gloss Finish for Solder Mask
>
>
> We are a CM and find that boards with a Matte finish are less susceptible
to
> solder balls at our wave processes.  We have discussed this with our flux
> suppliers and equipment suppliers and have read a few articles on why
solder
> balls are more likely to form on the gloss finish boards.  We have
received
> many recommendations on how to reduce or eliminate the solder balls
(change
> flux volume, change preheat, change this, change that) -- But, the one
theme
> from a root cause standpoint that recurs is the mask.
>
> What are the pro's and Cons of a Matte vs. Gloss finish for solder mask?
> Is one easier to apply, less expensive?
> Why would one be specified or used vs. the other?
>
> What is the specification for Gloss?  Normally I see "Solder mask per
SM-840
> Class T".  Is finish an option from a fab standpoint when it is not
> specified?
>
> Ultimately I'd like to be able to specify Matte Finish to the supplier,
but,
> I do not know how this may affect longevity of the board, cost, or even
> perception of quality.  I've heard some say that the end customers like
the
> way that the gloss boards look -- "shinier looks cleaner"?
>
> Any and all info including personal opinions about matte vs. gloss finish
> are welcome.
>
> Thanks,
> Carrie
>
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