With this tool you can precisely dispense very small dots of solder paste. Although this solder paste dispenser is cheap and uncomplicated, it works better for small SMD parts than many automatic dispensers.

There are many solder paste dispensers on the market, often motor controlled or pneumatically. But can you use them for very small solder dots? It is important that you are able to dispense micro-dots of solder paste, else it will easy lead to solder bridges. The problem with SMD soldering is always the excess of tin. That’s why I invented this hand-tool solder paste dispenser.

Precision SMD micro-dot solder paste dispenser
Precision SMD micro-dot solder paste dispenser

FOR SALE

Manual solder paste syringe dispenser. Included are also three blue plastic tapered tips and three syringes.

You can buy it on my shop here at tindie

For sale: SMD micro-dot solder paste syringe dispenser
For sale: SMD micro-dot solder paste syringe dispenser

Examples

I've used the syringe dispenser for assembling the Arduino SAMD21 board SAM 15x15: The SMD package 0402 is easy to do, see R1 and R2:

Manual assembling 0402 SMD parts
Manual assembling 0402 SMD parts

In de video below, I'm soldering 0603.

How to fill the dispenser with solder paste

Normally the solder paste is packed in a thick syringe. Take the thin dispensing syringe and remove the plunger. Then spray a little paste into the thin syringe, 15 mm is usually sufficient. Then insert the plunger and push the pasta all the way down.

Bent needle tips

There are all kinds of needles for sale that are suitable for the syringe:

Steel tapered bends needle
Steel tapered bends needle

Steel needles have a high resistance to the solder paste because they are thin over the entire length. Therefore, I use bend plastic tapered dispensing tips:

Plastic tapered bends needle
Plastic tapered bends needle

Needle diameter vs color

Needle colors are standardized according to Birmingham gauge.
Note that sometimes other colors are used, for example on AliExpress.
I recommend to use 22 - 27 Gauge tips for solder paste dispensing.

Gauge  Diameter [mm]  Color
22 0.41 blue
25 0.26 orange (sometimes red)
27 0.21 medium grey

I recommend to use only solder paste T5 for dispensing. 
The needle inner diameter should be larger than seven solder ball diameters. 

Cleaning and replacing dispenser tips

Immerse the tips in acetone to clean them.
I don't sell tips, you can buy them on eBay or Aliexpress.

Solder paste T4 (not prefered)

Particle size 20-38 [μm]

  • Gauge 22 
  • Gauge 25 
  • Gauge 27 

Solder paste T5 (prefered)

Chipquick SMD4300AX10T5
Mouser-nr. 910-SMD4300AX10T5

Particle size 10-25 [μm]

  • Gauge 27

Information

At the website of Nordson, you can find a lot of interesting information about solder paste dispensing:

Dispenser assembly

Mounting the syringe with spring requires some practice, be careful not to force the holder:

Sealing the dispense tip airtight

I used a piece of tap rubber for sealing:

Sealing a needle with tap rubber
Sealing a needle with tap rubber

Nanoliter / microliter pipette for laboratories

The micro-dot solder paste dispenser can also be used as a pipette to handle very small volumes of liquids in laboratories. For use for solder paste, it must be possible to accurately dose a volume from 10nL to 100nL.

Nanoliter / microliter pipette for laboratories
Nanoliter / microliter pipette for laboratories

Can we do 0201, 01005 and ball grid arrays manually?

With the dispenser we can handle SMD components with a package 0402 and larger easily. I was curious if even smaller components such as the 0201 could still be done with the dispenser. I have made a try, it was difficult but, in the end, it worked, I’m hopeful. But 0201 parts are hardly used anyway.

It is more important whether ball grid arrays can be done, then an expensive stencil may not be necessary anymore. I found out that the plastic bended tapered tip is too large for 0201 and BGA and the viscosity of the solder paste must be just right. I don't have time to investigate this further, but there may be people who see this as a challenge…

See my try here for the tiny 0201:

DIY soldering 0201 with a solder paste syringe dispenser

Ball grid array solder paste dispensing

On this image and video, you can see how solder paste dispensing is used for ball-grid arrays:

Ball grid array solder paste dispensing
Ball grid array solder paste dispensing

Low viscosity solder paste for the dispenser

The viscosity of solderpase is very critical to be able to apply micro-dots with a dispenser. We need low viscosity paste, this also sticks better to the PCB.
Common solder paste that works fine for stencils doesn't work with a dispenser, it is too syrupy:

Solder paste for stencils don't work with a dispenser
Solder paste for stencils don't work with a dispenser

The SMD4300AX10T5 soldering paste from Chip Quik is specially made for dispensing by a syringe. It is a thermally stable solder paste No-Clean Sn63 / Pb37 Type-5 in a 35g Syringe:

Chip Quik solder paste for syringe
Chip Quik solder paste for syringe

If you just have thick solder paste, you may try to it thinner by mixing it with for instance no-clean Topnik flux RF800. But don't expect miracles. Note that you need very little flux, less than a drop. The solder paste may not be too liquid.

Topnik flux RF800
Topnik flux RF800

Because of the mixing with flux, the solder paste will dry out in the syringe after some time.

Solder paste info

  • Solder paste is thixotropic, to lower the viscosity, it may be needed to stir the paste.
  • The paste must be at room temperature before use.
  • Note that the volume of the soldered joint is about half that of the solder paste applied.
  • There are special solder pastes for dispensing and stenciling

Solder pastes are classified based on the particle size, from type1 (160 µm) to type8 (11 µm), see Wikipedia.

Here you can see the solder paste with the solder ball particles very well here:

Solder paste with solder ball particles
Solder paste with solder ball particles

Precisely dispense the smallest amount of solder paste

The main thing that goes wrong with soldering surface-mounted devices is the excess of solder. On this extremely small PCB from an iPod touch, which contains 0201 size SMD, you can see how little solder paste is used:

iPod touch micro PCB with 0201 size SMD
iPod touch micro PCB with 0201 size SMD

Real size
Real size

After the components have been placed, you can solder the board as you like, with a reflow oven or hot air. I use the Atten AT858D to solder SMD parts, it is important that you can control both the temperature and the airflow.

Solder paste dispenser step 1Solder paste dispenser step 2SolderedSoldered

Solder flux storage

Nail polish jars are useful for storing solder flux for daily use. The brush is resistant to all kinds of chemicals.

Filling a nailpolish jar with solder flux for daily use
Filling a nailpolish jar with solder flux for daily use

Assembling 0402 SMD parts

Loupe

I use a loupe with 10x magnification. But keep in mind: the loupe must have a double lens to see the small SMD components well. Unfortunately, almost all loupes use just one lens.

Monocular jewelers 10x magnifying loupe with double lens
Monocular jewelers 10x magnifying loupe with double lens

Tweezers

Small SMD parts such as the 0402 require tweezers with a curved pointed tip:

Weitus WTS-817 curved pointed tip tweezers
Weitus WTS-817 curved pointed tip tweezers

More about the dispenser on the web

See HERE a a post from LarryD

FAQ 

  • How many pads are you able to tin with one filling?
    With 10mm of solder paste in the syringe you can already cover hundreds of SMD pads.

Do you have any comments about the website or problems with shopping? Please let me know.