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

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Mike Demos

#9028

Elimination of Silk Screen | 11 October, 1999

In a cost-reduction effort, our Design group is attempting to eliminate silk-screen (legend ink) on some new products. By the elimination of this process, there will be a slight decrease in the cost of the bare board.

Presently, the silk screen denotes reference designators on the circuit board. These are used for performing first piece inspection as well as troubleshooting.

I'd be interested to see opinions on this ...

Thanks!

Mike Demos

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#9029

Re: Elimination of Silk Screen | 11 October, 1999

| In a cost-reduction effort, our Design group is attempting to eliminate silk-screen (legend ink) on some new products. By the elimination of this process, there will be a slight decrease in the cost of the bare board. | | Presently, the silk screen denotes reference designators on the circuit board. These are used for performing first piece inspection as well as troubleshooting. | | I'd be interested to see opinions on this ... | | Thanks! | | Mike Demos

I suppose that the value of eliminating the screen would be highly dependent on volume but in our captive, high mix low volume shop they would have to shoot me before I would let them eliminate the silk screen. Every department finds them useful for the cost and we had to fight too hard to get them in the first place. John Thorup

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#9030

Re: Elimination of Silk Screen | 11 October, 1999

| In a cost-reduction effort, our Design group is attempting to eliminate silk-screen (legend ink) on some new products. By the elimination of this process, there will be a slight decrease in the cost of the bare board. | | Presently, the silk screen denotes reference designators on the circuit board. These are used for performing first piece inspection as well as troubleshooting. | | I'd be interested to see opinions on this ... | | Thanks! | | Mike Demos | Mike, here's the drill:

1 Your designers are trying to save 50� per board plus any NRE they take on rejiggering the designers in their CAD. Which is 50� per board total. 2 The troops in production and field support have to show that they have more than 50� of heart ache, frustration, lost time, and what not, because they do not have designaters on the board.

I like designaters, because they aid in communication. Writing work instructions without designaters is very hard, especially when operators reading skills are not great. I can see that they have limited value in some price sensitive products.

Good luck

Dave F

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Wendy Casker

#9031

Re: Elimination of Silk Screen | 11 October, 1999

Mike, Three Words: DON'T DO IT!!

Been there. It is a nightmare to work on boards without legends. Have the designers look elsewhere for the nickel they want to save.

Wendy

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Chris May

#9032

Re: Elimination of Silk Screen | 12 October, 1999

| In a cost-reduction effort, our Design group is attempting to eliminate silk-screen (legend ink) on some new products. By the elimination of this process, there will be a slight decrease in the cost of the bare board. | | Presently, the silk screen denotes reference designators on the circuit board. These are used for performing first piece inspection as well as troubleshooting. | | I'd be interested to see opinions on this ... | | Thanks! | | Mike Demos | Mike, I agree with the other guys & gals. If you have enough space on your boards then leave it on. The benefits far outweigh the cost savings of not having it. You will have a one off minimal saving per board and a revolution in assembly/inspection / test / service etc;

You are lucky to have the choice. The products I am dealing with as an OEM, are small CCD cameras on flexi-rigids that are "rolled up" into a small tube. We have no room literally for a silk screen legend. We have to manage with various visual aids etc; so I know the downsides.

As Wendy said, Don't Go There.Draw up a list of failings, predicted increases in build/inspection times & costs and present your case financially that way . I respect design guys a lot, I couldn't design my way out of a paper bag, but these guys don't have to build it.

Regards,

Chris.

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Mike Demos

#9033

Re: Elimination of Silk Screen | 12 October, 1999

Thanks for all of your replys. I will include these in our design review meeting tomorrow!

| In a cost-reduction effort, our Design group is attempting to eliminate silk-screen (legend ink) on some new products. By the elimination of this process, there will be a slight decrease in the cost of the bare board. | | Presently, the silk screen denotes reference designators on the circuit board. These are used for performing first piece inspection as well as troubleshooting. | | I'd be interested to see opinions on this ... | | Thanks! | | Mike Demos |

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Brian W.

#9034

Re: Elimination of Silk Screen | 12 October, 1999

| | In a cost-reduction effort, our Design group is attempting to eliminate silk-screen (legend ink) on some new products. By the elimination of this process, there will be a slight decrease in the cost of the bare board. | | | | Presently, the silk screen denotes reference designators on the circuit board. These are used for performing first piece inspection as well as troubleshooting. | | | | I'd be interested to see opinions on this ... | | | | Thanks! | | | | Mike Demos | | I suppose that the value of eliminating the screen would be highly dependent on volume but in our captive, high mix low volume shop they would have to shoot me before I would let them eliminate the silk screen. Every department finds them useful for the cost and we had to fight too hard to get them in the first place. | John Thorup | In the contract world, we do not always have a say in this, so we found some interesting ways to work around it. For example, some boards were too small to have any silk screen. In others, that $.50 was critical to the customers ability to compete. All work instructions had the designators on them, usually transferred from the CAD data. As we moved to a paperless factory, using work instructions generated from CAD data, having the ref des's on the board became less critical. It also decreased the time necessary to generate work instructions. At inspection and test, we had a real-time system that used smart graphics. It would bring up the board image to enter the data. All the operator had to do was click on the part on the computer screen, and all the information about the part was available from the CAD data. Our operators loved it, and didn't care about having ref des's on the board. They could also highlight circuit traces and compile other historical data.

What I'm trying to say is that it depends on the situation you are in and resources you have.

Brian

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se

#9035

Re: Elimination of Silk Screen | 13 October, 1999

As a stencil vendor to some assembly houses and small in-house assembly shops, both without CAD people rushing to put the paste layers (if they even generate one) into stencil friendly format, the silk screen is the only communication tool we have to reference items that may be questionable.

Try having a conversation with an assembly shop, a designer and a stencil vendor without a board (because we're all trying to produce our products just in time) and without a silk screen layer in the CAD file trying to decide what pads on what components to reduce for on the stencil. Keep any and all reference tools you can...Dan.

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