Surface Mount tightfist calling...


Senior Member
Here's, literally 5 minutes work, with a scrap PCB, some chipquick solder paste, a slightly sharpened wooden kebab stick (no cocktail sticks in this house, it seems) and about 5 mins under the current Mrs MartinM57's kitchen grill, set to max, about 40mm from the element, starting from cold until the solder melted and then the tray pulled out to for it all to cool naturally

View attachment 16123
yes, the via holes aren't in the middle of the via pads (but close enough, the PCBs work fine)
yes, I know the middle one should be a cap of some strange size but I put a 1206 resistor on it
yes, the top and bottom resisitors have pads for 1206 size but I put 0805 on
yes, the amount of solder is inconsistent - I was trying different amounts to see what was best - bottom right fairly obviously
I probably undercooked it - it didn't get hot enough to pull the components into line (or there wasn't enough paste to get enough surface tension to pull them)

...but it's not too bad for a first attempt in literally 5 minutes.

There was no fancy temperature profile - it just got hotter and hotter until the paste melted.

It does show that the key variable is amount of paste - it's a small amount but not too small - and it needs to be consistent. A stencil or some sort of adjustable constant (tiny) volume syringe pump is probably mandatory to get reliable results

The PCB pads are HASL (google it :)) so the solder on them will contribute to the overall amount of solder on the pads - it's just about enough to tack solder a component on for alignment without using any extra solder at all. If you had plated pads, you would probably need a fraction more paste.

Just need some feedback from Dippy on the Currys oven - PCB reflow good-enough for £25 or relegated (promoted?) to sausages?

Just about what I said in post #8.

Keep it simple .. is is not complicated at all.

Actually the amount of paste is not a big deal unless you go crazy. I got a couple of syringes from the pharmacy, cut the needle off to a short length and use it to place the paste ... Cost 25 cents US.


I think the amount is a big deal if you want to make boards like they've been made by something approaching "professionally"

My paste is already in a syringe - but I find it impossible to reliably get say a 1mm of paste on each pad by hand - my attempts result in something like a tolerance on that 1mm of -75% to +300%...and a second attempt on the same pad invariably makes a complete mess..
..anyone seen any DIY plans for a syringe pumper that can reliably eject 1mm of paste from a typical syringe/needle on some sort of button press?

Re post #8:
- the boards do look good - well done
- reheating a set/pack/side of ribs probably isn't a very common task in the UK :)


The oven is (alledgedly) arriving on Friday.
My Tesco order (with sausages) is arriving on the same day.

I found paste dispensing proportional to paste temperature; warm to the thumbometer.
I gave up with syringes and reverted to cocktail sticks.

I've tried the grill with mixed results, though my gut feeling is that those black plastic bodies will absorb heat more than shiny solder and I was a little worried about 'preferentially' heating the chip body. I have no scientific evidence; just the (probably innaccurate) imagination of an ageing physicist.
Hence the oven; albeit £25 of , no doubt, China's finest ;)

I'll report back - though I won't be starting off with a hundred poundsworth of Intel processor.
... I 'spose I'd better knock up a PCB and get some new cocktail sticks and paste (I'd forgotten).


Senior Member
Flat wooden toothpicks are my secret weapon for chasing solder bridges and applying small amount of paste... and for poking out through hole re-works..n and removing sausage pieces from teeth... :-0


I find it's a good idea to wipe the solder paste off the toothpick before removing sausage pieces from teeth.:)
I've actually remembered to order solder paste.
For my test I'll be using Multicore SN62RA10B.
I notice that a US Company produce a low temp variety; Amtech NC-31 which peaks at 165oC which might be an option.


Senior Member
..anyone seen any DIY plans for a syringe pumper that can reliably eject 1mm of paste from a typical syringe/needle on some sort of button press?
Yes... but I can't find it at the moment. If you're serious, I'll get back to you about it when I get home on Saturday.
I found a similar thing while looking for a way to inject 5ml of liquid chemicals into my aquarium reliably. It's basically a long worm/ACME thread you mount the syringe on and control with a stepper - obviously a great excuse for another 'AXE project to control it :D


Is it 'man enough' for stiff paste?
Often , if cold or old, you can press the plunger and nothing happens... then splooosh.. a great dob comes out.
It seems like if there is any 'give' (elasticity?) in the syringe/system then it might be prone to this.


My first attempt.

The £25 Logik oven has arrived from Currys.

Test 1. Sausages. 20 mins at (indicated) 230oC. Not bad. No picture as I have eaten them.

Test 2. A random grubby PCB from back of drawer. Paste (new Multicore Lead/tin) applied with cocktail stick.
I pre-heated oven to 50oC for 5 minutes before my test.
Set to 220oC (on the dial... real life I dunno).
Timer set to 5 minutes - but that was merely a backup in case the phone rang.
The poor victim was a PIC18F25K20.
And off we go...

First trycomp.JPG

If the solder looks lumpy then that's because of my lousy photography and shine.
The piccy looks a little distorted - camera on macro and wide-angle so that's bound to happen.
The solder flowed after around 2min 50s on my stop-watch.
I then opened the door and left it to cool.
I'm sure I can get it better - I was rather over-excited for the first one.

All in all I'm pleased, though I wouldn't leave it unattended without accurate external power/time control.
I'm sure someone with patience could actually modify the oven for more reliable performance - starting with a thermocouple I suspect.


Looks good for a first attempt Dippy - you must have a calibrated cocktail stick as the amount of paste on each pin looks pretty constant.

<<I'm sure someone with patience could actually modify the oven for more reliable performance - starting with a thermocouple I suspect.>>
I knew that thermocouple that came with my Fluke 87-v would have a use one day (after I got bored with measuring the in and out temps on the central heating radiators)....:)
...a nice manually-implemented PID algorithm - watch the temp, vary open angle of door by hand, keep in place with wedges (not potato)

I'm tempted - if it doesn't work for me, I could always use it in my shed/workshop for a couple or three Wall's thick pork'ers when required


Cheers Martin.
It's an ESD compliant wooden cocktail stick. Plus bent-end Swiss-made tweezers and UK-made eye magnifier and a Scotch whisky to calm the nerves.

Aha, yes, PID control and a servo door-opener and away you go ;)

Oh, of course, the final bit of info. The PIC still programmes.
A fat lot of use soldering nicely if you zap the components.
The 3 minute mark for solder melt ties in roughly with real profiles.

Needless to say that, after ordering it, I found a proper reflow oven + squeegee paste thing + P&P at work gathering dust in a backroom.

I must borrow a thermocouple from work. My IR thermometer went potty at>150oC and it said 104oC at the 100oC setting which can't be right.


Senior Member
With IR emissivity of surface test becomes very important... might have to make special target... or just watch when wooden stick starts to smoke...


I have a matt black target for that so I'm well aware, but you've highlighted where so many go wrong with the 'magic' IR measurements.
I'm fairly pleased after checking the prices of proper reflow ovens. 25 quid plus a penny for a cocktail stick is a good result. :)


so did you put individual blobs on each pad, or just two solid lines worth. I can't get a similar amount on so many pads, it ranges from far too much to hardly any at all


Martin, you should be asleep and not thinking about solder paste :)

I did that example with individual blobs - a slow process, possibly 5 minutes. If I can find another gash board I'll try a couple of lines.

My preferred dispensing tools are 1. a sharp wooden cocktail stick or 2. the lead of a 0.5W resistor.
Or, if the paste is stiff, using both like chopsticks.
High precision huh?

Slight aside - stencils. do a 2 (working) day turnaround for £13.50 + £1.50 postage (or Next DaY Courier £6.50).
Quote: "Results are reliable down to ~ 0.4mm pitch on 75 micron. 0.8mm pitch will be fine on either 100 micron or 75 micron (I would advise 100 micron)."
Stencil size is A4 (plastic) and they'll do 2 merged files or two copies of one file per sheet in that price.

I don't want to start a I-can-get-them-for-tuppence competition, so this is merely FYI.


Senior Member
"tuppence" is that anything like "Tupperware" that the girls purchace and fill the cupboards for a rainy day need, that never comes.


That paste press looks robust - I bet it's way better than a normal plastic syringe.
And I'm sure I'd be a lot more wobbly than the demonstrator in the video clip.


Senior Member
Haha, yes. Well I could get the ex-MIL to breathe on the board but I think that would singe my DIPs.

I'm tempted to get one and experiment. Plus a steak & kidney pie.
I won't bother with fan. Too much hassle to get it right and pukka fan ovens are quite a robust build.

I was looking around for a proper reflow oven and had to sit down when I saw the prices.

Oh yes srnet, I've spent an awful lot of time doing it by hand... that's what has impaired my eyesight.
Dippy - Make one of these. I use mine all of the time for various projects from trimming plastic bits to soldering components.


Senior Member
That paste press looks robust - I bet it's way better than a normal plastic syringe.
And I'm sure I'd be a lot more wobbly than the demonstrator in the video clip.
I just use the syringe. It is a learning experience - getting the quantity right takes practice. Shaky hands do not matter much - the paste melts and evens out before it liquifies into solder.

The bulk nozzles are a great idea. Cleaning used nozzles is a pain in the b....