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electroformed stencils

Al Carrillo

#11221

electroformed stencils | 3 June, 1999

Hi everybody,

Somebody know the advantages of electroformed stencils on laser cut stencils ?

any coment is apreciated.

thanks

Al

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Earl Moon

#11222

Re: electroformed stencils | 3 June, 1999

| Hi everybody, | | Somebody know the advantages of electroformed stencils on laser cut stencils ? | | any coment is apreciated. | | | thanks | | Al | We use electroformed when xtra or very fine pitch devices are involved. Very expensive proposition though just a little more than laser. Just for information, we use laser cut mostly in step down requirements when using xtra/very fine pitch or uBGA applications with those non-fine pitch. Another note is we use PSI, mostly, in CO Springs.

Earl Moon

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DNC

#11223

Re: electroformed stencils | 3 June, 1999

| Hi everybody, | | Somebody know the advantages of electroformed stencils on laser cut stencils ? | | any coment is apreciated. | | | thanks

Deon Response:

Hi Al,

Electroforming a is basically an atomic post lazer plating chemical process. (Previously Xerox patented.)Resulting in smother apertures. Thus better paste release for very high$$$'s.

For my typical assmebly process I personally do not see much of an advantage that will justify using electroforming process. I prefer ( a much less$$) lazer/chemetch process on stencils with any devices >.020" pitch spacing. Which have yielded my process excelent results. My main stencil supplier is I-Source in Irvine, CA and has pretty much standardized on 100% lazer cut stencils for competetive pricing. Hope this helps.

Deon Nungaray SMT Mfg. Engineer GMI Inc. USA CA

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Earl Moon

#11224

Re: electroformed stencils | 3 June, 1999

| | Hi everybody, | | | | Somebody know the advantages of electroformed stencils on laser cut stencils ? | | | | any coment is apreciated. | | | | | | thanks | | Deon Response: | | Hi Al, | | Electroforming a is basically an atomic post lazer plating chemical process. (Previously Xerox patented.)Resulting in smother apertures. Thus better paste release for very high$$$'s. | | For my typical assmebly process I personally do not see much of an advantage that will justify using electroforming process. I prefer ( a much less$$) lazer/chemetch process on stencils with any devices >.020" pitch spacing. Which have yielded my process excelent results. | My main stencil supplier is I-Source in Irvine, CA and has pretty much standardized on 100% lazer cut stencils for competetive pricing. | Hope this helps. | | Deon Nungaray | SMT Mfg. Engineer | GMI Inc. USA CA | | Deon,

Outstanding! I worked at Xerox (xrocks) in the late 60's and early 70's in Pomona. This is where we used electroforming to construct the gold plated, aluminum, light amplification mirror assemblies for some of the earliest night vision devices. Electroforming provided, as it does still, very precise surface finishes on which to rely for whatever application. The process hasn't changed much, just the application.

Earl Moon

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Steve A

#11225

Re: electroformed stencils | 3 June, 1999

| Hi everybody, | | Somebody know the advantages of electroformed stencils on laser cut stencils ? | | any coment is apreciated. | | | thanks | | Al | Hey Al,

An Electroformed (an additive process) stencil is comparable quality wise as a laser cut/Electropolished (a removal process)stencil.

Electroformed stencils are primarily used for wafer bumping and applications when a thin stencil (under .003") is necessary. Thickness can be specified to the nearest .0001", so if you want a stencil at .0023, you can get it made.

Both laser and Electroformed stencils can provide a trapezoidal aperture, but the electroformed process provides an additional aperture lip (or they call a gasket).

Another application is for standard SMT stencils when the process is cheaper than Laser cutting due to a high number of apertures. In electroforming, all apertures are created together, thus cost is regulated by the X, Y and Z dimensions of your stencil and not by aperture count. Say the set cost for a 26" x 26" x .005" Electroformed stencil is $1000. If you have 10,000 fine pitch apertures, a laser stencil may cost $500 (with 2000 fine pitch apertures) and each additional aperture might cost 10 cents. That stencil would then cost (.1 x 8000) + $500 = $1300. A wafer bumping stencil may have 50,000 apertures.

Hope this helps.

Steve A

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#11226

Re: electroformed stencils | 3 June, 1999

| | Hi everybody, | | | | Somebody know the advantages of electroformed stencils on laser cut stencils ? | | | | any coment is apreciated. | | | | | | thanks | | Deon Response: | | Hi Al, | | Electroforming a is basically an atomic post lazer plating chemical process. (Previously Xerox patented.)Resulting in smother apertures. Thus better paste release for very high$$$'s. | | For my typical assmebly process I personally do not see much of an advantage that will justify using electroforming process. I prefer ( a much less$$) lazer/chemetch process on stencils with any devices >.020" pitch spacing. Which have yielded my process excelent results. | My main stencil supplier is I-Source in Irvine, CA and has pretty much standardized on 100% lazer cut stencils for competetive pricing. | Hope this helps. | | Deon Nungaray | SMT Mfg. Engineer | GMI Inc. USA CA | Deon: I agree that AMTX, Inc. (Advanced Microfabrication Technology) was a part of Xerox, I believe the business is shuttered. I believe that electroplating is more like a deposition process than "an atomic post lazer plating chemical process." Check the link below for a more coherent description.

Al: Check the archives for suppliers.

Ta

Dave F

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John Thorup

#11227

Re: electroformed stencils | 3 June, 1999

| | | Hi everybody, | | | | | | Somebody know the advantages of electroformed stencils on laser cut stencils ? | | | | | | any coment is apreciated. | | | | | | | | | thanks | | | | Deon Response: | | | | Hi Al, | | | | Electroforming a is basically an atomic post lazer plating chemical process. (Previously Xerox patented.)Resulting in smother apertures. Thus better paste release for very high$$$'s. | | | | For my typical assmebly process I personally do not see much of an advantage that will justify using electroforming process. I prefer ( a much less$$) lazer/chemetch process on stencils with any devices >.020" pitch spacing. Which have yielded my process excelent results. | | My main stencil supplier is I-Source in Irvine, CA and has pretty much standardized on 100% lazer cut stencils for competetive pricing. | | Hope this helps. | | | | Deon Nungaray | | SMT Mfg. Engineer | | GMI Inc. USA CA | | | Deon: I agree that AMTX, Inc. (Advanced Microfabrication Technology) was a part of Xerox, I believe the business is shuttered. I believe that electroplating is more like a deposition process than "an atomic post lazer plating chemical process." Check the link below for a more coherent description. | | Al: Check the archives for suppliers. | | Ta | | Dave F | I have never had the need to use anything but electropolished chem etch down to 25 mil or laser down to 20 mil. I believe that the results are a "softer" stencil that tends to wear out sooner than stainless. John W has previously suggested Chepaume Industries in NY for electroformed stencils (315/768-7001) JT

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se

#11228

Re: electroformed stencils | 4 June, 1999

Al,

We make stencils, and I was personally involved at AMTX when the electroformed process was developed. Some of this will sound like an ad, but everyone has been volunteering vendors and so look at this as a suggestion.

Electroforming is an additive process, nickel plated to a brass sheet or mandrel with resist bumps that prevent plating in the areas where the apertures are going to be. The lip or gasket formed around the aperture is the plated nickel building or climbing the side of the resist during the plating process. It can be dialed-in to very specfic thicknesses as was suggested above. However, cost and turnaround can be a problem because the resist has a tendency to fall off during plating and several attempts are needed to produce a quality product.

Electroplating nickel to a laser cut stencil can also be done to minimize the sidewall scoring that takes place during the cutting process. The nickel helps the paste release in smaller apertures. There are also, electroplating techniques used on screens to increase durability over polymer emulsions.

Nickel is soft, even the "XL" brand AMTX had before it was sold to a competitor of mine. Xerox sold it (AMTX), that should tell you something right there. Too small a market, too high a price, too limited a competitive edge. If anyone reading this is using nickel, be sure to use a nickel squeege blade, the stainless blades will chew-up the nickel eventually.

I would recommend a good chemetch-electropolished stencil first for apertures down to 8 mils wide in their smallest dimension. We do that stuff all the time at half the cost of laser or electroformed nickel and the customers are more than pleased to save the money. I recommend Hybrid Screen Technologies @ 800-219-9950 in Minneapolis for your stencils.

Good luck...Dan H.

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tannlin

#11229

Re: electroformed stencils | 7 June, 1999

| Hi everybody, | | Somebody know the advantages of electroformed stencils on laser cut stencils ? | | any coment is apreciated. | | | thanks | | Al

Al As far as I am aware most of the big OEM's and CEM's have tried and rejected frameless stencils - so unless space saving counts for more than quality you have to question this technology.

Fraser |

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tannlin

#11230

Re: electroformed stencils | 7 June, 1999

| Hi everybody, | | Somebody know the advantages of electroformed stencils on laser cut stencils ? | | any coment is apreciated. | | | thanks | | Al

Al

I have a quote for you from one of the major CEM's

"anyone who thinks they are controlling paste volumes using an electroformed stencil is kidding themselves" | Perhaps someone can give us a spec on the resulting foil thickness variation on a REAL production stencil. It is well known that uniformity of plating current density is almost impossible to achieve on a foil with variation in aperture density ( a REAL stencil!) so the foil thickness will vary. On top of that you have all the other Photo mechanical tolerances to worry about each of which will affect regestration and aperture accuracy. Electroformed stencils do have very clean apertures which will print better than a poor quality laser stencil. Unfortunately many people think that all laser stencils are the same. This is plainly not true some have cleaner cuts than others some have sharper draught angles than others and some have better axis control and hence better accuracy and registration. The only true way of testing a stencil is to use a proper paste volume measurement system.

Fraser

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