Spoty precision SMD micro-dot solder paste dispenser
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. It is used in aerospace and medical electronics companies.
Buy it on Tindie
You can buy it on my shop here at Tindie.
There are many solder paste dispensers on the market, often motor controlled or pneumatically. But can you use them for very small solder dots such as for 0201 SMD resistors? It is important that you are able to dispense the smallest amount 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.
The dispenser is very ergonomic and lies slanted in the hand like a pen:
How to manually assemble 0402 SMD components
I prefer to always 0603 components, because they are very easy to assemble by hand. Assembling the smaller 0402 parts by hand is not that easy. You must be able to apply micro dots of solder paste, otherwise you will get short circuits.
This video demonstrates how to apply tin to the small 0402 parts (not 0603) with the Spoty solder paste dispenser:
Placing the SMD 0402 parts manually. If the components are close together you need very fine tweezers:
I always place all SMD components on the PCB first, without aligning them exactly. Alignment during assembling makes no sense because you always accidentally bump to another component. When all components are in place, I align them using a sewing needle:
What's the difference with other solder paste dispensers?
The difference with other solder paste dispensers is that the Spoty has a thinner syringe and the lever is larger, so that you can dose much smaller dots, which is needed for 0402 and 0201 parts.
Manual solder paste syringe dispenser. Included are also two blue plastic tapered tips and two syringes.
You can buy it on my shop HERE at Tindie.
With the sale, I can partly finance my hobby: inventing and publishing it. The further development of my Maxun One solar bike is expensive, many parts are unique and are manufactured by companies to my specifications.
The dispenser is very simple as you can see, it seems made of cheap plastic. But manufacturing is not cheap, it is made of strong nylon PA12 and fabricated with a $225,000 EOS FORMIGA P 110 SLS 3D printer.
For the assembly of the springs, see below in this article.
You can also buy the extra solder paste option, where one syringe is filled with 4 grams high quality TS391AX10 (type T4) soldering paste from Chip Quick. Then you can get started right away without having to buy additional solder paste elsewhere. Note that the solder paste you may already have is probably too thick for the thin 22G tip. If the solder paste you have doesn't go through the 22G tip then you will need to use a larger tip.
To give an impression of how much you can do with 4 grams: Not more than 3mm length of the solder paste in the syringe is needed for these three boards:
Prefered Chipquick solder paste
To be able to apply micro-dots of solder paste, the tip that I provide has a small diameter of 22G. This has the consequence that ticker solder paste that works with other dispensers doesn't work with the 22G blue tip.
I have tested several types of solder paste, but only the SMD4300AX10T4 soldering paste from Chip Quik works fine with the tiny 22G blue tip.
It is specially made for dispensing by a syringe. It is a thermally stable solder paste No-Clean Sn63 / Pb37 type-4 in a 35g Syringe:
You can buy it at Mouser, Digikey and Amazon, but they are often sold out.
To easily fill the syringes I modified a nozzle:
The following solder pastes don't work well:
- TS391AX50 type 4 in jar 50g: it sticks badly to the PCB and is therefore difficult to apply.
- SMD4300AX10T5 type 5 in syringe 35g: when heated, the tin spreads out over the PCB and causes short circuits.
- SMD4300AX250T5 type 5 in jar 250g: same problem as SMD4300AX10T5 but slightly better.
Watch out for bad solder paste
- If the syringe was filled with paste a few days ago, you should squirt out the first part, without using it, as this may be unreliable.
- Solder paste is a critical product, if it has been stored too long or used too quickly after being refrigerated, it will no longer work properly. You can then mess up an entire PCB. If you are not sure if the paste is still good, first make a test PCB with a few SMD components.
Discrete 741 operational amplifier in DIL8
Here is a challenge to take on with the solder paste dispenser. Using the solder paste dispenser to make a 741 operational amplifier in DIL8 with discrete transistors.
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:
You can buy the parts yourself here:
Stainless steel compression spring
- Length 20mm
- Wire diameter 0.6mm
- Outer diameter 6mm
- Spring constant k about 0.9 N/mm
Bended TT tapered dispensing tips
- 22G Blue
- 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.
- How can I clean the dispenser tip?
Immerse the tips in acetone to clean them.
- Can the solder stay in needle or clean each time?
You can leave it in the needle, but you should always squirt out and discard the first portion of tin before you start.
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 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:
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.
|25||0.26||orange (sometimes red)|
Smallest recommended dispense tips for solder paste T4
I recommend to use only solder paste T4 for dispensing.
The needle inner diameter should be larger than seven solder ball diameters.
Particle size 20-38 [μm]
- Gauge 22
- Gauge 25
- Gauge 27
At the website of Nordson, you can find a lot of interesting information about solder paste dispensing:
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 faucet rubber with a drilled hole for sealing:
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.
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…
Ball grid array solder paste dispensing
On this image and video, you can see how solder paste dispensing is used for ball-grid arrays:
More about solder paste
- 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.
- Chip Quik: shelf life refrigerated 3-8C (37-46F) > 6 months, unrefrigerated > 2 months.
- Chip Quik: allow 4 hours for solder paste to reach an operating temperature of 20-25C (68-77F) before use.
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:
Common solder paste that works fine for stencils doesn't work with a dispenser, it is too syrupy:
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:
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 flux storage in a nail polish jar
Nail polish jars are useful for storing solder flux for daily use. The brush is resistant to all kinds of chemicals.
Applying minimal tin to solder tip with solder balls
With solder wire it is difficult to apply a very small amount of tin to a solder tip, that's easier with solder balls:
Small raised SMD work table
With small parts such as SMD you have to sit with your eyes close to the work. To be able to do this comfortably, I made a small raised work table of wood:
Double lens loupe for SMD
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.
High temperature grease for Hakko soldering irons
To prevent seizing of the nozzle screw, apply high temperature grease to the thread:
You can use Hakko 800-026 Anti Seize Lubricant or just any high temperature fauset grease.
Micro Soldering Microscope
I came across an interesting website Microsoldering that sells all kinds of tools and stuff needed to repair smartphones. For example, here is a microscope:
Fake copy from China
In august 2021 there was a shop, named Biggluck, in China that had copied my solder paste dispenser and also all my photos and videos were copied entirely on their website. However, after ordering, the money was always refunded. I think it was just to investigate how big the sales market is:
Small SMD parts such as the 0402 require tweezers with a curved pointed tip:
More about the dispenser on the web
See HERE a a post from LarryD