OSH Stencils ????

TC

Hello all,

I was wondering if anyone has used OSH Stencils before? I like the prices they offer, but they seam a little cheep to me. $0.60USD a square inch?!?!

How was the quality, shipping, etc....

Thanks
TC

Erik Friesen

If you ever try a real stainless stencil.... Its hard to be satisfied with polyimide, or any plastic.

TC

Ive never used a stencil before, never needed to. but now I have a few projects that could benefit using stencils.

How bad could plastic stencils be if they are only getting use a couple of times?

Erik Friesen

Its ok for a few, better than paste by hand. The biggest thing about plastic is that its hard to keep flat, and it the cut edges can have burrs.

TC

Thats what I was hoping for. I have 3 boards that have .5mm parts on it, and I was going to use a thin paint brush to put on the paste. But a stencil would be better. I'm just afraid I will pay for a service that I will not be happy with.

SRLM

TC wrote: »

Thats what I was hoping for. I have 3 boards that have .5mm parts on it, and I was going to use a thin paint brush to put on the paste. But a stencil would be better. I'm just afraid I will pay for a service that I will not be happy with.

A paint brush won't work at all. Solder paste is much thinker, like clay. Better than a paint brush would be a tooth pick. Even better is a syringe with a fine tip (the pressure helps prepare the paste).

Using plastic stencils for a 0.5 part might be a challenge. I tried it for a part with 0.45 and it didn't work very well at all. Solder paste would get stuck in the holes and miss pins entirely.

TC

SRLM wrote: »

A paint brush won't work at all. Solder paste is much thinker, like clay. Better than a paint brush would be a tooth pick. Even better is a syringe with a fine tip (the pressure helps prepare the paste).

Using plastic stencils for a 0.5 part might be a challenge. I tried it for a part with 0.45 and it didn't work very well at all. Solder paste would get stuck in the holes and miss pins entirely.

So it might be best just to use a toothpick. I dont want to spend an arm and a leg just for three boards that are about 1 square inch.

Don M

I have used their service and was satisfied with it. I have also used stainless steel. The smallest parts I placed with the mylar stencil were 0805.

Perhaps the only thing I didn't like about the mylar stencil was the fact it was small and flexible vs larger and rigid for the stainless. The stainless was easier to hold in place while "squeegy"ing the paste on.

The cost savings for mylar for a small run of boards, especially if you aren't 100% finalized on the design far outweighs the inconvenience factor.

tonyp12

I used OSH Stencil for 0603 no problems and I even did this little thing (pads done by me)

A LM4570 that is 2mm x 2mm (pads are 0.4 x 0.3)

File attached, it's NOT a zip file so rename .zip to .asc

OSHStencils

TC wrote: »

Hello all,

I was wondering if anyone has used OSH Stencils before? I like the prices they offer, but they seam a little cheep to me. $0.60USD a square inch?!?!

How was the quality, shipping, etc....

Thanks
TC

TC,

Our edge quality and precision is higher than what you may be used to with Kapton and Mylar.

Give us a try, if you aren't happy, I'll make it right

-Brent

TC

tonyp12 wrote: »

I used OSH Stencil for 0603 no problems and I even did this little thing (pads done by me)

A LM4570 that is 2mm x 2mm (pads are 0.4 x 0.3)

File attached, it's NOT a zip file so rename .zip to .asc

Don M wrote: »

I have used their service and was satisfied with it. I have also used stainless steel. The smallest parts I placed with the mylar stencil were 0805.

Perhaps the only thing I didn't like about the mylar stencil was the fact it was small and flexible vs larger and rigid for the stainless. The stainless was easier to hold in place while "squeegy"ing the paste on.

The cost savings for mylar for a small run of boards, especially if you aren't 100% finalized on the design far outweighs the inconvenience factor.

Thank you for the input. im still on the fence about needing a stencil. but I am afraid I will short out a few pins and have to start all over again.

TC

tonyp12 wrote: »

I used OSH Stencil for 0603 no problems and I even did this little thing (pads done by me)

A LM4570 that is 2mm x 2mm (pads are 0.4 x 0.3)

File attached, it's NOT a zip file so rename .zip to .asc

Thats great! my part has the same pad dementions just more pins ( TI's RGY pacage )

Also, I could not rename your file.

TC

OSHStencils wrote: »

TC,

Our edge quality and precision is higher than what you may be used to with Kapton and Mylar.

Give us a try, if you aren't happy, I'll make it right

-Brent

OK!?!? was not expecting that.
I will try you guys out in a couple weeks (Christmas can be a killer), you seam to have a good product, and people are recommending you, and like I said "I like the price". You just cant tell what kind of a service someone has by there website.

Thank You

tonyp12

>Also, I could not rename your file.
to rename a file extension, you need to be able to see them first.

1.Start Windows Explorer, you can do this by opening up any folder.
2.Click Organize.
3.Click Folder and search options.
4.Click the View tab.
5.Scroll down until you notice Hide extensions for known file types, un-check this line by clicking the check box.
6.Click OK

WBA Consulting

Polyimide stencils on a laser can be used down 0402s, I cut a stencil for for a board with 23 0402s about 2 weeks ago. There are a few tricks, which hopefully OSH has figured out already. In my opinion, the main trick is to never cut (vector) a polyimide stencil, but always engrave (raster) through it. This provides a much cleaner edge and therefore a better paste release from the apertures. The power and speed combination needed to cut Polyimide does not leave a clean, flat, square edge rsulting in poor printing and release.

Depending on the complexity of the board, I use either 2 mil or 5 mil Polyimide and the highest resolution, 1200 dpi. You can print some very fine features with the 2 mil thickness, but your printing process must be dialed in so you aren't fighting insufficient solder issues to the point they cause opens.

I make my stencils on an Epilog Legend EXT 75 watt (same as Parallax) using GC PowerPlace (a paid upgrade of the free viewer GCPrevue) because it allows me to edit the gerber which in turn allows me to make apertures exactly the way I want. This is the next trick. When making stencils out of Polyimide or Mylar, your apertures should be modified to compensate for the material's weaknesses as well as for it's strengths. As an example, I use circular apertures for 0402 pads. I get cleaner paste release than if I used a rectangular pad because they are so small.

I will not use mylar for anything smaller than 0805 as it is just not worth the hassle. Pololu's mylar stencils are a prime example. I had a customer try ordering mylar stencils from them earlier this year for two separate PCBs and the results were unusable. I ended up cutting Polyimide stencils for both instead, even after Pololu re-cut one of them in efforts to address our concerns.

As for stenciling boards with paste, you can find a lot of youtube videos showing the DIY method. Solderpaste has the consistency of toothpaste and should be spread with a firm tool; I use a plastic putty knife. Use just enough pressure that you do not leave smear streaks of paste on top of the stencil. On this other thread by TonyP12, I list out what I use to paste PCBs at home using stainless steel stencils, but most of the process is the same for polyimide.

TC

tonyp12 wrote: »

>Also, I could not rename your file.
to rename a file extension, you need to be able to see them first.

1.Start Windows Explorer, you can do this by opening up any folder.
2.Click Organize.
3.Click Folder and search options.
4.Click the View tab.
5.Scroll down until you notice Hide extensions for known file types, un-check this line by clicking the check box.
6.Click OK

Ill have to try that once I get home after work.

TC

WBA Consulting wrote: »

Polyimide stencils on a laser can be used down 0402s, I cut a stencil for for a board with 23 0402s about 2 weeks ago. There are a few tricks, which hopefully OSH has figured out already. In my opinion, the main trick is to never cut (vector) a polyimide stencil, but always engrave (raster) through it. This provides a much cleaner edge and therefore a better paste release from the apertures. The power and speed combination needed to cut Polyimide does not leave a clean, flat, square edge rsulting in poor printing and release.

Depending on the complexity of the board, I use either 2 mil or 5 mil Polyimide and the highest resolution, 1200 dpi. You can print some very fine features with the 2 mil thickness, but your printing process must be dialed in so you aren't fighting insufficient solder issues to the point they cause opens.

I make my stencils on an Epilog Legend EXT 75 watt (same as Parallax) using GC PowerPlace (a paid upgrade of the free viewer GCPrevue) because it allows me to edit the gerber which in turn allows me to make apertures exactly the way I want. This is the next trick. When making stencils out of Polyimide or Mylar, your apertures should be modified to compensate for the material's weaknesses as well as for it's strengths. As an example, I use circular apertures for 0402 pads. I get cleaner paste release than if I used a rectangular pad because they are so small.

I will not use mylar for anything smaller than 0805 as it is just not worth the hassle. Pololu's mylar stencils are a prime example. I had a customer try ordering mylar stencils from them earlier this year for two separate PCBs and the results were unusable. I ended up cutting Polyimide stencils for both instead, even after Pololu re-cut one of them in efforts to address our concerns.

As for stenciling boards with paste, you can find a lot of youtube videos showing the DIY method. Solderpaste has the consistency of toothpaste and should be spread with a firm tool; I use a plastic putty knife. Use just enough pressure that you do not leave smear streaks of paste on top of the stencil. On this other thread by TonyP12, I list out what I use to paste PCBs at home using stainless steel stencils, but most of the process is the same for polyimide.

That Is a lot of great info, Thank you for the advice.

TC

tonyp12 wrote: »

>Also, I could not rename your file.
to rename a file extension, you need to be able to see them first.

1.Start Windows Explorer, you can do this by opening up any folder.
2.Click Organize.
3.Click Folder and search options.
4.Click the View tab.
5.Scroll down until you notice Hide extensions for known file types, un-check this line by clicking the check box.
6.Click OK

I did it, now I found another problem, I dont have dip-trace, I use Eagle.

OSHStencils

Although we have a couple images on our website showing the quality, this link provided by one of our customers who compared our service to another well known provider of stencils should give you a good indication of our precision. It was taken under a microscope at very high resolution. 0.2mm apertures, and 0.5mm spacing.

http://imgur.com/dIHKSOK,KQMr1QV

We have several companies using our service for rapid prototyping with high precision components.

If you aren't happy with the results, we'll make it right

-Brent

TC

OSHStencils wrote: »

Although we have a couple images on our website showing the quality, this link provided by one of our customers who compared our service to another well known provider of stencils should give you a good indication of our precision. It was taken under a microscope at very high resolution. 0.2mm apertures, and 0.5mm spacing.

http://imgur.com/dIHKSOK,KQMr1QV

We have several companies using our service for rapid prototyping with high precision components.

If you aren't happy with the results, we'll make it right

-Brent

WOW Brent, that is impressive. on the Ohararp stencil you can see the inaccuracies between holes. I do have to say, you have my business after Christmas.