Recommendations for Solder Paste Printer

[ehughes]

I am looking for any recommendations for a decent solder paste printer.

1.)    This is for low volume in-house prototypes
2.)    Max board size will be 8x11
3.)    No budgetary requirements as of yet.  This would be my 1st purchase so I am unsure what is a good price target for my application.  It looked like decent printers were $2k to 4k.

[ivaylo]

Stencil and a squeegee not good enough?

[jmelson]

I've done several thousand boards with an unframed stencil etched from .003" brass shim stock.  I had a tooling plate with a grid of 10-32 holes on 1" centers.  I made some bars with a step on one edge to hold the board, and grooves so that socket head screws could hold the bars and adjust their position to just hold the board by the edges.

I use masking tape to make a living hinge for the stencil.  I apply the tape to one edge of the stencil, align the stencil to the board and then press the tape down onto the bars.  After applying the paste, I hinge up the stencil and take out the board.  This really works well, and these stencil aligner-printer units are way overkill for anything less than full production work.

Jon

[DTJ]

I use masking tape to make a living hinge for the stencil.  I apply the tape to one edge of the stencil, align the stencil to the board and then press the tape down onto the bars.  After applying the paste, I hinge up the stencil and take out the board.

Jon

I do the same only I use vinyl duct tape for the stencil hinge - it sticks REALLY well but still removes cleanly. I found masking tape didn't stick hard enough for my fumble fingers.

[Corporate666]

at the price point you mentioned, I am guessing you are talking about a manual printer?

There is a pretty good thread on manual printers here:

https://www.eevblog.com/forum/manufacture/looking-for-framed-stencil-printer/

I bought this one:

https://www.aliexpress.com/item/high-precious-TK3245-double-side-SMT-PCB-stencil-printer/32827005614.html

and after a little tweaking, I am very happy with it.  It was producing somewhat inconsistent results, but I went through the whole thing and tightened up all the nuts and bolts which removed all of the slop and play, and after doing so, I get beautiful results. 

Previously we would tape boards to a flat surface and tape a frameless stencil on top and screen, then lift the stencil and put new boards in.  It worked OK, but getting registration perfect was always a challenge, and after pasting maybe 10 boards, the tape loosened and it would throw things off.

The printer I linked to above can easily print dozens and dozens of boards one after another and they are all equally perfectly aligned.

[janekm]

Like others I would suggest you try printing without a "printer" frame first. I've visited assembly shops in Shenzhen which have the fancy printer (like that TK3245) but don't use it except on very rare exceptions, as the setup time isn't worth it. With a bit of practice you can just line up the stencil on each board and print.

A good quality squeegee may be more important 

[Corporate666]

Like others I would suggest you try printing without a "printer" frame first. I've visited assembly shops in Shenzhen which have the fancy printer (like that TK3245) but don't use it except on very rare exceptions, as the setup time isn't worth it. With a bit of practice you can just line up the stencil on each board and print.

A good quality squeegee may be more important 

Having printed many thousands of boards both ways, I would disagree that the manual printer takes long to setup, or that it takes longer than a frameless stencil taped to a desk. 

If you tape the board down, you have to tape some PCB scraps to make a frame, line up the stencil manually and tape it down and paste - then do the same for the other side. 

The printer gets rid of all the taping and lining up hassles.  The only extra work is putting the pins in the base to support the board, but this doesn't take much time at all.

Cleanup is easier with framed stencils since excess paste is contained.

If you are printing 1 or 2 boards at a time and neither method is already set up, I'd say it takes the same amount of time.  If you are doing more than 5 or 10, the actual stencil printers linked are faster.  If you're doing 0603 sizes or QFN's, a real stencil printer makes it much easier to align and get repeatable/accurate results, too.

[ehughes]

We currently use the "tape it down method".   It is OK for some designs but 0.5mm pitch QFPs almost always result in in shorts that involve rework.   Also,   it makes cleaning the stencil difficult in between applications. After a couple lifts the orientation is off a bit.

The volume is pretty low here as we go to a real assembly house when real quantities but would like to avoid as much rework as possible when doing small development batches.   That and I am getting prepped for a 0.65mm BGA and would like to get a bit better setup.

For some prototypes we do use a the real fab house but often times the lead time is not acceptable for the small prototypes.

[jmelson]

Not all my boards have 0.5mm pitch, but a lot of them do.  I rarely have any problem with solder bridges due to that.  My P&P machine is not accurate enough for that lead pitch chip, so I sometimes have to manually touch up the alignment.  But, it is not the fault of the stencil alignment.  Also, not all boards are routed that accurately, so unless you align each board to fiducials, you can only get the stencil so close.

Jon

[DerekG]

We currently use the "tape it down method".   It is OK for some designs but 0.5mm pitch QFPs almost always result in in shorts that involve rework.

Perhaps consider using a thinner solder paste stencil.

[janekm]

Like others I would suggest you try printing without a "printer" frame first. I've visited assembly shops in Shenzhen which have the fancy printer (like that TK3245) but don't use it except on very rare exceptions, as the setup time isn't worth it. With a bit of practice you can just line up the stencil on each board and print.

A good quality squeegee may be more important 

Having printed many thousands of boards both ways, I would disagree that the manual printer takes long to setup, or that it takes longer than a frameless stencil taped to a desk. 

If you tape the board down, you have to tape some PCB scraps to make a frame, line up the stencil manually and tape it down and paste - then do the same for the other side. 

The printer gets rid of all the taping and lining up hassles.  The only extra work is putting the pins in the base to support the board, but this doesn't take much time at all.

Cleanup is easier with framed stencils since excess paste is contained.

If you are printing 1 or 2 boards at a time and neither method is already set up, I'd say it takes the same amount of time.  If you are doing more than 5 or 10, the actual stencil printers linked are faster.  If you're doing 0603 sizes or QFN's, a real stencil printer makes it much easier to align and get repeatable/accurate results, too.

I didn't explain it well enough... they don't tape either the board or the stencil, just line up the framed stencil on top of the PCB. With a lot of practice it's quicker than either other method, but not really advisable for someone who only does it once in a while, I suppose...

[jmelson]

We currently use the "tape it down method".   It is OK for some designs but 0.5mm pitch QFPs almost always result in in shorts that involve rework.

Perhaps consider using a thinner solder paste stencil.

Right, I use a 0.003" stencil, and reduce the aperture size to about 50% of the pad area on fine-pitch parts to avoid shorts.  I'm still learning the optimum aperture size, but this seems to be getting pretty good.

Jon

[l0wside]

Thinner stencils (120µm, i.e. 0.005") are usually just fine down to about 0.4mm pitch. 0.003" sounds more like foil.

On each PCB prototype order, I am haggling with myself whether to spend the extra money for a proper stainless steel stencil or not. With one-sided boards, the polyimide stencils by OSH Stencils are just fine. With two-sided boards, it is a PITA as you can´s place the board properly - with the stencil printer, life is a lot easier.

Just my 2ct.

Max

[jmelson]

Thinner stencils (120µm, i.e. 0.005") are usually just fine down to about 0.4mm pitch. 0.003" sounds more like foil.

No, in brass, it is still fairly stiff stuff.  MUCH stiffer than kitchen aluminum foil, for instance.  But, yes, it is noticeably less stiff than .005" brass, which is what I started with.  To avoid bridges, the apertures would have to be REALLY small with a .005" stencil, that's why I went down to .003"

Jon

[sugi]

I made a solder stencil printer for less than $50.

https://youtu.be/06pBT5ii6Hc

[Reckless]

I have a couple for sale in the $4500 range.  They are MPM fully automatic which are much nicer and easier to use especially for small fine pitch components.

I'm in Chicago and can ship from my office.

[soubitos]

very nice implementation! Where does one find those hinges and do they have a specific "name" i can search for them online?

[TimCambridge]

Where does one find those hinges and do they have a specific "name" i can search for them online?

"Butterfly hinge clamps" or just "hinge clamps." A pair should cost you around $20.