Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Joe Manzur

#12295

Pump Printing Glue. | 15 March, 1999

Hello,

Is there anybody screen printing glue on the underside of the PCB, when there are through leads, dip, axial & radial parts already cut and clinched into the board?

Is there anybody just printing glue on a flat substrate?

If the answer to either is YES, is it a success in a production environment? Has anybody had any good/bad experiences.

Joe.

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Joe Manzur

#12296

Screen Printing Glue | 18 March, 1999

| Hello, | | Is there anybody screen printing glue on the underside of the PCB, when there are through leads, dip, axial & radial parts already cut and clinched into the board? | | Is there anybody just printing glue on a flat substrate? | | If the answer to either is YES, is it a success in a production environment? Has anybody had any good/bad experiences. | | Joe. | | |

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Scott Davies

#12297

Re: Screen Printing Glue | 30 March, 1999

We have carried out some experimental work, in conjunction with DEK. Instead of dispensing adhesive for SMD components onto the bottom side of on of our PCBs, we have looked at the possibility of screen printing the adhesive. Because, at the stage of adhesive application, the PCB has through hole leaded components inserted, we have had to use a thicker stencil (plastic, 3-4mm) with channels machined about 2mm deep into the stencil to take the protruding leads. The remainder of the stencil has holes drilled through to print the adhesive dots onto the board.

For the PCB we have trialled this process on, we have seen a dramatic reduction in cycle time from about 2 mins (dispensing) to about 25 secs (printing). We spent a lot of time perfecting the printing parameters, but the process has proved to be repeatable and reliable.

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#12298

Re: Screen Printing Glue | 31 March, 1999

| We have carried out some experimental work, in conjunction with DEK. Instead of dispensing adhesive for SMD components onto the bottom side of on of our PCBs, we have looked at the possibility of screen printing the adhesive. Because, at the stage of adhesive application, the PCB has through hole leaded components inserted, we have had to use a thicker stencil (plastic, 3-4mm) with channels machined about 2mm deep into the stencil to take the protruding leads. The remainder of the stencil has holes drilled through to print the adhesive dots onto the board. | | For the PCB we have trialled this process on, we have seen a dramatic reduction in cycle time from about 2 mins (dispensing) to about 25 secs (printing). We spent a lot of time perfecting the printing parameters, but the process has proved to be repeatable and reliable. | Scott: Interesting project.

1 Were you dispensing adhesives and paste? 2 How many dots were you dispensing on each board? At what rate? 3 What was the unit volume in each production run? 4 How did the improvements in adhesive dispense time improve the tact time of your placement machine? 5 How does the setup time compare between the two machines?

Thanks

Dave F

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Scott Davies

#12299

Re: Screen Printing Glue | 1 April, 1999

Dave,

Thanks for the interest.

Basically, we looked at this project as a straight swap, i.e. printing the glue on the PCB using a Dek screen printer instead of our current method of dispensing glue using a Camalot dispensing machine. For the PCB we trialled, there was no solder paste, only glued bottom side SMD components and thru-hole top side components; the PCB was wave soldered when all of these parts had been fitted.

We currently run our glue dispenser (a Camalot 3800) at about 12000 dots per hour. The board we trialled had 1100 individual glue dots, so it would take 5� mins to process on the Camalot. We reduced this cycle time to 30 secs by printing.

For virtually all of our boards which go through the Camalot machine, the glue cycle time currently exceeds the SMD placement cycle time by about 10 - 20%. Therefore, by printing glue we would see a significant improvement in placement efficiency.

Set up times for the two processes are roughly the same, although the glue stencil is notoriously difficult to clean afterwards. We are soon to invest in a stencil spray cleaner which will make this task a lot easier.

Dek Precision Screen Division in the UK have been instrumental in driving this technology. Let me know if you require any further information.

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