0 Members and 1 Guest are viewing this topic.
Check now
ehughes
Recommendations for Solder Paste Printer
«
on: December 22, , 03:46:57 pm »
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
Re: Recommendations for Solder Paste Printer
«
Reply #1 on: December 23, , 08:25:43 am »
Stencil and a squeegee not good enough?
jmelson
Re: Recommendations for Solder Paste Printer
«
Reply #2 on: December 24, , 04:01:27 am »
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
Re: Recommendations for Solder Paste Printer
«
Reply #3 on: December 24, , 04:06:43 am »
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
Re: Recommendations for Solder Paste Printer
«
Reply #4 on: December 24, , 05:38:08 am »
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-TK-double-side-SMT-PCB-stencil-printer/.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.
It's not always the most popular person who gets the job done.
janekm
Re: Recommendations for Solder Paste Printer
«
Reply #5 on: December 24, , 06:48:00 am »
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 TK) 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
Re: Recommendations for Solder Paste Printer
«
Reply #6 on: December 24, , 11:03:31 am »
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 TK) 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 sizes or QFN's, a real stencil printer makes it much easier to align and get repeatable/accurate results, too.
It's not always the most popular person who gets the job done.
ehughes
Re: Recommendations for Solder Paste Printer
«
Reply #7 on: December 24, , 07:06:56 pm »
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
Re: Recommendations for Solder Paste Printer
«
Reply #8 on: December 24, , 11:43:55 pm »
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
Re: Recommendations for Solder Paste Printer
«
Reply #9 on: December 25, , 12:55:19 am »
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.
I also sat between Elvis & Bigfoot on the UFO.
janekm
Re: Recommendations for Solder Paste Printer
«
Reply #10 on: December 26, , 07:37:14 am »
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 TK) 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 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
Re: Recommendations for Solder Paste Printer
«
Reply #11 on: December 26, , 06:09:35 pm »
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
Re: Recommendations for Solder Paste Printer
«
Reply #12 on: January 02, , 10:38:05 am »
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
Re: Recommendations for Solder Paste Printer
«
Reply #13 on: January 03, , 02:40:57 am »
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
Re: Recommendations for Solder Paste Printer
«
Reply #14 on: September 03, , 05:30:37 pm »
I made a solder stencil printer for less than $50.
https://youtu.be/06pBT5ii6Hc
DIGH TEC
https://digh.com
Reckless
Re: Recommendations for Solder Paste Printer
«
Reply #15 on: September 03, , 07:18:12 pm »
I have a couple for sale in the $ 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.
« Last Edit: September 03, , 07:28:03 pm by Reckless »
soubitos
Re: Recommendations for Solder Paste Printer
«
Reply #16 on: April 10, , 08:34:54 am »
very nice implementation! Where does one find those hinges and do they have a specific "name" i can search for them online?
TimCambridge
Re: Recommendations for Solder Paste Printer
«
Reply #17 on: April 10, , 11:44:29 am »
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.
What is a SMT stencil?
SMT Stencil is a thin metal sheet used in the soldering process for SMT (Surface Mount Technology) and it plays an essential role in the SMT soldering process. Smt Stencil allows the direct placement of solder paste onto the SMD pads of PCB, which can help prevent errors and defects during the reflow soldering process. This results in a precise amount of tin coverage once the work is completed.
Types of SMT Stencils
Depending on the application of solder paste, there are three different types of stencils that are generally used.
Framed SMT Stencils
Framed PCB stencils are mostly ready to use. Framed stencil consists of a normal laser cut stencil sheet stained to the metal frame. This type of stencil is most suitable for high-volume SMT assembly due to the frame's ability to provide better stability and reusability of the stencil itself.
Frame of the stencil also allows a better and faster process of alignment between the PCB and stencil.Cost of the frame stencil is relatively higher due to the need for additional frame support . Moreover, frameworks require additional storage space and can be more complex to manage. It also makes stencil heavier, increasing shipping costs.
Frameless Stencil
Unlike framed stencils, frameless stencils do not have a surrounding frame, making them more economical than framed stencils. This design allows for the direct placement of the stencil onto the PCB and it’s mostly suitable for hobby and non repeatable usage. Frameless stencils are very light which makes them great for shipping.
Due to no additional frame support being required, it is more suitable for small batch PCB printing and allows for custom sizes.Like framed stencils, frameless stencils can be customized to accommodate specific PCB designs and component layouts.
Step Stencil:
There are various components on the PCB, and each component has different solder paste requirements during the soldering process. Regular laser stencils can only regulate the amount of solder paste by adjusting the size of the openings while overall thickness of the stencil is the same everywhere.
In order to meet higher standards and requirements for soldering effectiveness and quality, some engineers require multiple solder paste thicknesses on the same SMT template to achieve precise control of the solder paste amount. This requirement leads to the use of a step stencil. It allows for printing varying solder paste thicknesses on the same stencil, enabling precise control of the solder volume.
With competitive price and timely delivery, Ling Yueyang sincerely hope to be your supplier and partner.
How to Choose Your Own SMT Stencil ?
The thickness of SMT Stencil
The thickness of stencil is a crucial factor in determining the quantity of solder paste which is being placed onto the PCB pad. During the printing process of the stencil, the bottom of the stencil sheet comes into contact with the top surface of the PCB board. Therefore, the thickness of the stencil determines the thickness of the solder paste that is printed onto the surface of the PCB pad.
- The thickness of SMT stencil should be determined based on the density of PCB components, packaging form and size, and the spacing between pins (or BGA solder balls). If the spacing between components is small, use thinner ones. If the components on the entire PCB are relatively large, a thicker stencil can be used.
- On the same PCB, there are both general spacing components above 1.0mm and narrow spacing components. The thickness of the stencil should be selected based on the condition of the majority of components on the PCB board. Popular way to reduce or enlarge the amount of the solder paste applied on the solder pad is by adjusting the pad opening on the stencil. In the PCB design software, this is being done in the “Solder Paste” layer.
- When components require significantly different amounts of solder paste, localized thinning of the stencil for components with narrow spacing can be employed. However, the thinning process incurs higher manufacturing costs. Therefore, a compromise can be made by choosing an intermediate thickness for the stencil to determine the solder paste requirements.
- For general pitch components, the opening can be 1:1. However, for larger components that require a significant amount of solder paste, the opening area should be increased by 10%-20%. For OFP and other components with pin pitches of 0.65mm and 0.5mm, the opening area should be reduced by 10%.
SMT Stencil material
The main materials used for laser cut SMT Stencil include stainless steel and copper. Stainless steel has a higher hardness, longer service life, and better corrosion resistance. On the other hand, copper has better electrical conductivity, which can enhance production efficiency. Stainless steel is the most commonly used material for making PCB stencils. It is undoubtedly the best material for producing a PCB stencil.
Size of a SMT Stencil
The outline size of the smt stencil needs to be selected based on the actual size of the PCB board. Specifically, the appropriate size of the stencil sheet should be selected based on parameters such as the shape and spacing (line width/line spacing) of the PCB board to prevent errors during the production process.
Your stencil needs to be sufficiently large to accommodate the board data within the valid area of the stencil, rather than the stencil size. The valid area refers to the central region where SMT pads can be cut into the sheet, while the remaining space forms the stencil margin and cannot be cut. But how to choose ?
SMT size specifications are diverse .
Below this text you can find commonly used specifications and sizes at JLCPCB about framed stencil:
For some electronic engineers, their PCB prototypes are sometimes within a size of 10x10cm or less. If the current conventional stencil is used, a significant portion of the stencil sheet area will be wasted as shown below, resulting in a highly uneconomical situation. And it is very large and heavy, which makes it inconvenient to transport and store.
To avoid such situations and reduce cost , JLCPCB supports the production of frameless SMT stencils with customized outline size, price start only $7 !There are no frames or different types of glues, which simplifies the process and enhances production efficiency. It can also be transported together with the PCB to save on shipping costs if the customized size is smaller than 200x200mm.
Let’s learn how to place a smt order at jlcpcb through the video below.
The company is the world’s best SMT Stencil Printers supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.
Conclusion
All Comments ( 0 )