SMD Construction tips?

[G8PEF]

We don't appear to have a section for general discussion about construction, so since my latest construction activity (and thoughts arising from it) were Portsdown related, I'm posting in here …

Whilst wrestling with 0805 SMD components, recently - mainly trying to flick them off the tip of my soldering iron, it seems - I wondered how everyone else goes about their SMD construction?
Firstly, how do you all observe what you are doing? I use a stereo microscope at between 8x and 12x magnification, normally - I find this works reasonably well as long as you have decent light directed at the PCB.

And how do you all position and then hold your components in place - particularly 0805 Rs & Cs - to stop them sticking to the tip of your iron while soldering? I usually use a pair of s/steel tweezers, nudging the components into place, then use the tip to apply a little pressure to hold the component down while one end is soldered.

Next, what do you do about tidying up the joints? Even with a fairly fine pointed bit, I find that there's usually excess solder on the joints … I use a bit of solder wick to soak up some of the solder and leave a neater joint.

Any other tips & tricks for SMD work?

73
John

[G8GKQ]

Hi John

Colin G4KLB has done a video with some good tips in it: https://www.youtube.com/watch?v=LSy3r85QB4E

The technique I use for small components (taught be Kevin G3AAF of the Finningley Club) is to have a fine point on a vertical press that provides downward pressure on the small component while you solder the first end. Put a small drop of liquid flux (sold by Kevin at very reasonable rates) on that specific area of the board first. Use very fine solder and a very fine iron tip and then you don't end up with excess solder.

Dave

[G8PEF]

Hi, Dave

Thanks for your reply. I had already seen Colin's video, some time ago, but it was a good refresher and I'm using much the same kit and techniques as in the video (for the ICs). Thanks for the info on your method for holding the 0805s still, too - I had spent some time looking for a cocktail stick this afternoon - I was going to clamp it in a small pair of mole grips and rest the pointy end on the SMDs, using the weight of the moles to apply pressure . I was thwarted though, by my inability to find a cocktail stick, so had to settle for using the tweezers.

Edit: yes, OK on Kevin's liquid flux - which I do have a bottle of - I seem to remember him talking me into buying a bottle at a rally (Elsecar?) a couple of years ago, lol.

[VK5BI]

I find a jewellers screwdriver kit very useful for holding the components in place.

Wayne

[M0YDH]

Self-closing tweezers save on swearing. I open my long reach, angled tip tweezers, touch the bottom of the pcb with one tip then close gently on the speck of component. You'll get those under your microscope. The aforementioned golf ball loaded pin clamp may not fit there.
Vacuum clean the carpet under the bench before starting the project......

David

[G8PEF]

Thanks, Wayne and David, for your comments. The self-closing tweezers idea is interesting' but I don't know of any really fine-point ones.
Vacuum? Carpet? bench? - haha, I only wish I could get into the workshop at the moment; these boards were constructed on the kitch'en worktop. Luckily, I only lost one 0805 capacitor during both sessions - the one that stuck to my iron and pinged off into the great unknown when I tried to get it off, lol.

Anyway, today I had a crack at the LO filter PCB - having acquired some .38mm solder - and successfully completed it in a lot less time than I thought it would take. I had some trouble with the SMD inductors because of the 'leads' not extending up the sides of the former very far. Even with a very fine bit in the iron it was hard to get the solder to flow onto the component as well as the pad. I managed eventually, and the other components didn't put up too much of a fight, so it was all good in the end.

I guess it's time to wire it all together and see if it works, now

[gordon]

Before starting my Portsdown project, I purchased a practice board which included many different types of components, including IC's. I spent a day playing with it, trying out different ways of soldering. Finally, I concluded that LEADED solder paste was the way to go, putting a small amount on each pad. Then place the component using right angle tweezers and carefully hold it in place with the wrist placed on a stable surface. Any movement must come from the wrist and fingers, not the arm, or its impossible to hold the tweezers still. Then use a fine tip iron to melt the solder paste. Turn the board around and do the other end. All the paste will wick up to the pads and the end of the component.

Now for the IC's. Place a thin string of solder paste ACROSS all of the IC pads; don't try and put a little bit on every pad, it won't work. Carefully sit the IC on the pads having checked its the right way around. It works best with a hot air gun and the paste all goes under the IC pins as if by magic; I had no shorts. This part can also be done with a fine tip iron but you will find that you get shorts which must be carefully dragged off with the tip of the iron; far better to use hot air.

I use a circular bench magnifying lamp. I did purchase a magnifying wearable visor but, for me, it was useless and, after 5 minutes, I put it to one side.
Anyway, good luck and hope this is of some help.

Gordon, G3ZYL