Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Solder mask registration

Yngwie

#21773

Solder mask registration | 27 September, 2002

Dear all, My customer is asking me to add chevron solder mask registration marks to their board design, drive fabrication capability study from their board vendor(s), and make sure tolerances are established correctly for copper traces and solder mask opening. We were asked to review their pad/trace/solder mask design to verify if there are any potential issues.

Can someone help me to understand what is that means by chevron solder mask, and what is the advantage of adding this chevron solder mask, to ensure good registrations and how can this help. Likewise, what would be the potential issues if this is added/not added and what is the criteria for it. What is the limit does the PCB manufacturer has in order to meet my customer requirement esplly on the mask registration.

Pls guide me on this matter.

TQ

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pr

#21775

Solder mask registration | 27 September, 2002

Chevron marks are sets of lines (at right angles, on either side of component) placed on the board to help verify placement (we used it on BGA's) since you can't look at lead to pad to check placement accuracy. That's the only time I've seen it used.

good luck, pr

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Yngwie

#21779

Solder mask registration | 27 September, 2002

Thank you pr. It was much appreciated.

Is this mark normally act like a global fiducial/local fiducial for mBGA ? Is this a standard mark that can be read by the placement machine? what is the typical size of this mark ? are they masked ?

thank you

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pr

#21781

Solder mask registration | 27 September, 2002

We used it only for operator verification of placement accuracy, your boardhouse should be able to show you examples of what they look like. They basically outline the outside edge (corner)of the part so you have a visual, after placement (since you can't see ball to pad). Once you see them on the board you will understand immediatly, I'm sure.

good luck, pr

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#21793

Solder mask registration | 1 October, 2002

Board fabricators purchase laminate in preferred panel sizes, such as: 16 x 18 inches, 18 x 24 inches, and 21 x 24 inches. A larger panel size provides more effective cost per unit area processed. In producing a board, the fabricator requires maybe 3/4� around the outer edges of the pane for tooling and processing. So, an 18 x 24 inches panel only has a usable area of 16.5 x 22.5 inches available for an active board.

For process set-up and control, fabricators put all kinds of coupons and registration targets that they use on: * Coupons * Registration targets * Tooling holes * Electrical connection * What not

Your customer has determined that they like chevron [�V�] shaped registration targets. It�s curious how they even determined their preference. Assemblers and users don�t even see registration targets. Registration targets are not an element of the board design, because if they were, your customer would have added the registration targets themselves. Registration targets are an element of the fabricators� internal process control. It�s like fiducials. Some machines can image on any old feature. Other machines require a fairly specific feature to image on. The fabricator knows what they prefer for their process.

I think it�s interesting that your customer is asking you to: * �Add chevron solder mask registration marks to their board design. * Drive fabrication capability study from their board vendor(s). * Make sure tolerances are established correctly for copper traces and solder mask opening. * Review their pad/trace/solder mask design to verify if there are any potential issues.�

So, tell us. For you do this: * When are they cutting a PO? * How much are they paying you? * How did you or your boss even price-up a job like this? * How many hours do figure this is going to take to complete?

What the hey, if you�re making good money and making your customer happy, life is good. And you�ll be able to learn a heck of a lot about fabrication on your customer�s nickel.

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