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Screen tension (measuring)

George Verboven

#12276

Screen tension (measuring) | 15 March, 1999

In the early days, we used screens made of stainless steel or polyester. Sometimes - after A period - the tension was not good, because A wire was broken. Later on we started to us metal stencils, glued in A polyester screen. even than we had sometimes problems with the tension. Nowadays we use metal stencils from DEK (Vector mask) that is clamped in A frame from Micromount. This solved our problem. So what is the question?:

Well, our customer strictly demands that we buy and use A screen tension measuring equipment. As far as I know it has no sense to measure this on A system like we have now, because there are no wires that can be broken. So who has experience with this, has our customer right in arguing that we need it?

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#12277

Re: Screen tension (measuring) | 15 March, 1999

| In the early days, we used screens made of stainless steel or polyester. Sometimes - after A period - the tension was not good, because A wire was broken. | Later on we started to us metal stencils, glued in A polyester screen. even than we had sometimes problems with the tension. | Nowadays we use metal stencils from DEK (Vector mask) that is clamped in A frame from Micromount. | This solved our problem. So what is the question?: | | Well, our customer strictly demands that we buy and use A screen tension measuring equipment. | As far as I know it has no sense to measure this on A system like we have now, because there are no wires that can be broken. | So who has experience with this, has our customer right in arguing that we need it? | | George: As more companies strive to achieve industry certification, they place greater emphasis on process control. In the current business environment, knowing that you can deliver defect-free product is not enough, you must be able to prove it to your customer.

Some customers take a prescriptive approach, kinda like the old mil specs. And then find themselves "wrapped around the axle" (or izzit axial) with conflicting demands and burdensome costs. Other customers take a more descriptive approach by defining the conformance of the end-product.

It�s possible that your customer, with good intentions, lacks insight in how to describe what is really required ("We want paste to be printed real nice. Er, really, we want nice solder connections, according to 610B.") and is twitchin a little bit when thinking too much about your stencil frame. If you can�t steer �em to the path, how about:

1 "Dropping a US Govmnt (or what ever) one cent piece (or what ever) from a height of 12 inches will cause the penny to rebound from the surface of a properly tightened stencil by a height of greater than 6 inches." Eeeyew the dropping the coin could damage the stencil couldn�t it? How about "Dropping a regulation US Table Tennis Association �" 2 That�s going no where. How about specing the torque on the screws?

Good luck

Dave F

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George Verboven

#12278

Re: Screen tension (measuring) | 16 March, 1999

| | In the early days, we used screens made of stainless steel or polyester. Sometimes - after A period - the tension was not good, because A wire was broken. | | Later on we started to us metal stencils, glued in A polyester screen. even than we had sometimes problems with the tension. | | Nowadays we use metal stencils from DEK (Vector mask) that is clamped in A frame from Micromount. | | This solved our problem. So what is the question?: | | | | Well, our customer strictly demands that we buy and use A screen tension measuring equipment. | | As far as I know it has no sense to measure this on A system like we have now, because there are no wires that can be broken. | | So who has experience with this, has our customer right in arguing that we need it? | | | | | George: As more companies strive to achieve industry certification, they place greater emphasis on process control. In the current business environment, knowing that you can deliver defect-free product is not enough, you must be able to prove it to your customer. | | Some customers take a prescriptive approach, kinda like the old mil specs. And then find themselves "wrapped around the axle" (or izzit axial) with conflicting demands and burdensome costs. Other customers take a more descriptive approach by defining the conformance of the end-product. | | It�s possible that your customer, with good intentions, lacks insight in how to describe what is really required ("We want paste to be printed real nice. Er, really, we want nice solder connections, according to 610B.") and is twitchin a little bit when thinking too much about your stencil frame. If you can�t steer �em to the path, how about: | | 1 "Dropping a US Govmnt (or what ever) one cent piece (or what ever) from a height of 12 inches will cause the penny to rebound from the surface of a properly tightened stencil by a height of greater than 6 inches." Eeeyew the dropping the coin could damage the stencil couldn�t it? How about "Dropping a regulation US Table Tennis Association �" | 2 That�s going no where. How about specing the torque on the screws? | | Good luck | | Dave F | |

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George Verboven

#12279

Re: Screen tension (measuring) | 16 March, 1999

Thanks Dave,

But still I have the following question unanswered, in a technical point of view: Has it sense to measure this on A system like we have now, because there are no wires that can be broken.

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#12280

Re: Screen tension (measuring) | 16 March, 1999

| Thanks Dave, | | But still I have the following question unanswered, in a technical point of view: | Has it sense to measure this on A system like we have now, because there are no wires that can be broken. | George: While I agree that no wires can be broken, I'm not sure that having no wires is sufficient reason for not making sure that your stencil is taut enough (secured to the frame properly) to print properly. For me, measuring the tautness of the stencil is not the answer. Obtaining outstanding looking bricks of paste and properly attaching components are the measures of a stencil that is properly tensioned (amoung things). TTYL Dave F

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Dan Hughes

#12281

Re: Screen tension (measuring) | 23 March, 1999

George,

No it does not make sense to measure the tension on a mounted foil, however, if you wish to please your customer you might want to find a tension gauge that measures in mils of deflection.

In the beginning, screen tensions were all measured with deflection gauges. A one ounce weight is connected to a micrometer that measures its movement. Any suspended material will deflect under wieght. The micrometer measures the travel. A uniform spec. should be possible and your customer will be happy.

The gauges are typically less than $1000, but are hard to find, but they do exist. good luck...dan.

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