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Stencil maintenance approaches

Stencil maintenance approaches

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Hello, do you perform any stencil maintenance? What type of... - Sep 08, 2021 by Evtimov

Hello Evtimov , two parammeters must be controlled : 1) ... - Sep 09, 2021 by Djo

Thank you for your reply Djo. What do you consider a normal ... - Sep 09, 2021 by Evtimov

how thick is the stencil to measure? in µm , 29 µm ? ... - Sep 09, 2021 by Djo

We have built millions of circuit boards and do not perform ... - Sep 09, 2021 by Sr. Tech

Sr.Tech, do you evaluate the SPI data to capture any wear ou... - Sep 09, 2021 by Evtimov

Stencil thickness could be 3,4,5,6 mil but stencil is framed... - Sep 09, 2021 by Evtimov

I have never witnessed a "worn out" stencil in my ... - Sep 09, 2021 by Sr. Tech

I do not know of a way to measure the nano-coating. However,... - Sep 09, 2021 by Mike Vina

You don't really need to measure the center's thickness unle... - Sep 09, 2021 by Thomas

Evtimov , i agree with Thomas.. you don't have to take your ... - Sep 10, 2021 by Djo

Evtimov

#87032

Stencil maintenance approaches | 8 September, 2021

Hello,

do you perform any stencil maintenance? What type of controls do you use? Also interested if you have a way to measure nano coating thickness? Any ideas will be appreciated.

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Djo

#87033

Stencil maintenance approaches | 9 September, 2021

Hello Evtimov ,

two parammeters must be controlled : 1) Frames tension must be controlled with tension meter ( attached photo ) 2)Also stencil thikness must be controlled with a Micro meter palmer

Attachments:

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Evtimov

#87035

Stencil maintenance approaches | 9 September, 2021

Thank you for your reply Djo. What do you consider a normal range tension for 29" stencil on a hard frame? Also I am not sure how I can use micrometer in the middle of 29" stencil to measure the thickness? CAn you please clarify?

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Djo

#87040

Stencil maintenance approaches | 9 September, 2021

how thick is the stencil to measure? in µm , 29 µm ?

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Sr. Tech

#87041

Stencil maintenance approaches | 9 September, 2021

We have built millions of circuit boards and do not perform "stencil maintenance"

Your SPI machine is the judge.

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Evtimov

#87042

Stencil maintenance approaches | 9 September, 2021

Sr.Tech, do you evaluate the SPI data to capture any wear out of the stencils/coating?

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Evtimov

#87043

Stencil maintenance approaches | 9 September, 2021

Stencil thickness could be 3,4,5,6 mil but stencil is framed on 29 inch frame for SMT printer machine. I want to measure thickness in the center of this frame.

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Sr. Tech

#87044

Stencil maintenance approaches | 9 September, 2021

I have never witnessed a "worn out" stencil in my 30+ years. Take that with a grain of salt..My environment is CM so stencil usage is somewhat limited.

I have seen "coined" stencils. They look funky but some schools of thought say they work better because they conform with contours of the circuit board.

If you are thinking the middle of your stencil is thinner because of wear, that would take hundreds of thousands of cycles unless you have something weird going on with your printer parameters or squeegees.

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Mike Vina

#87048

Stencil maintenance approaches | 9 September, 2021

I do not know of a way to measure the nano-coating. However, it is easy to check if it is still on the stencil. Simply use a 'sharpe' pen and try and mark the bottom (PCB) side near any openings. If it easily marks, then the nano is no longer present, if it beads-up then the nano is still present.

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Thomas

#87049

Stencil maintenance approaches | 9 September, 2021

You don't really need to measure the center's thickness unless there is where the step up/down is at. As long as you can measure the the outer edge of the stencil, it would be the same thickness.

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Djo

#87051

Stencil maintenance approaches | 10 September, 2021

Evtimov , i agree with Thomas.. you don't have to take your mesure in the middle of the stencil since the sheet of the stencil has the same thickness everywhere either in the corners or in the middle.. So you can ask from your stencil supplier to make for you a small removable window in one of the corners to be able to remove it and take the thickness measurements on .. For the center of stencil , all that you need to control is stencil tension . Exp : Stencil with 100µm thinck => tension must be upper than 33N .

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