11 February 2016 By mencinger



Electronic 5V DC powered Solder paste Dispenser AIR FREE
/ AIR LESS operation V2
  The goal to build this Dispenser was to be as cheep as possible and to avoid using any 3D printed parts! But still reliable and safe for use by hobby guys and school kids for low volume of PCBs.

This solder paste dispenser is generally to be used with any solder paste in a syringe (or flux, liquid, glue) – syringe volume 10 to 15 cc.

Two buttons for PRESS and RELEASE turn the stepper motor shaft left or right and move piston in syringe in chosen direction and force the liquid or paste in syringe to move out through needle.

Dispenser has built in very powerful stepper motor with full metal gear gearbox witch with tremendous pressure forces paste or liquid out of the syringe. Basic use is for SMD SMT solder paste application to PCB for reflow soldering.

Appx. 25x PRESS-ings make 1 (one) rotation of the piston which moves the piston for apx. 0.5-1mm (0,019685 -0,3494 dec. inch) in the syringe.

I tested this V1 and V2 of Dispenser with several different Solder Paste Manufacturers and different needle sizes:

1) Blue/metric 0,41mm – US/Gauge 22

2) Purple Gage 21 – 0.51mm

3) Gauge 23-24 (inside Dia 0.38 -0.41 mm)

and as well stepper motor force produced – apx. 14 kg / 30 pounds

Power Supply needed is 5V DC (0.5 to 1A).  I simply use USB cable and phone charger or computer USB port, spare phone USB battery pack… or similar.

Due to fact that many Solder Paste Co. request in manuals storage of the Solder Paste in cool areas with 0-10deg C storage temperature please note that Syringes stored in fridge shall be heated up with hot air/ shrink tube hot air gun / hair drier or in hot water to 40-60 deg C for better viscosity of solder paste for use with this dispenser.

You have to take into account that this Dispenser is not as fast as air dispenser but it is fast enough to keep you doing right thing! I have placed a few videos on my YouTube – test with different needles and paste… have a look!!

Here is a procedure we worked-out with one of my German client: I quote the email text:

I didn’t pre-heat the solder paste, just took it out of the fridge and let it rest for some hours at room temperature. I built up pressure until some paste came out of the needle and then released the pressure. First I tried pressing and instantly releasing again, but it was quite hard to get the right amount of paste on the pads…. It was a success with pressing and not releasing after. While the paste was slowly flowing I just did pad after pad and always got the right amount. I tried different needles and it worked even with really narrow ones. Did some DFNs, TQFPs, SSOPs, and many 0603s. Worked really neat, just had to remind me to build new pressure once in a while  I like the dispenser and I’m happy to finally leave my toothpick method behind me
Best regards,

I would highly recommend BEGINERS NOT TO start with metal needles but with but with PLASTIC CONICAL outlets!!

For more information, please visit my website. Thank you!

UPDATE: January 13th, 2016

V2 two buttons for PRESS and RELEASE were replaced in V3 with Joystick and turn the stepper motor shaft left or right and move piston in syringe in chosen direction and force the liquid or paste in syringe to move out through needle. Each dispensing step forward has automatic return in order to prevent solder paste to dispense uncontrolled.

In addition to Joystick a small push switch was added to change the speed/steps of stepper motor (5 step speed) in order to precisely control the volume of dispensing solder paste. Speed is indicated with 5 Led lights. ISP connector is available for upgrade of software.

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