'Hold Down Jig' to aid SMD soldering

[David G4EBT]

I have a chum who is building a transceiver kit, which includes some SMD components to solder. Tricky to do without a means of holding the component in place, leaving both hands free to solder the device. I've made him a little 'hold-down' jig to aid the process. No claim for originality and it's an 'MFJ' project - 'made from junk' - just bits I had lying around. The base is 7" x 5", and the stand is 6 " high. I used a piece of 3mm diam brass rod for the hold-down tip, which will act as a heat sink to be kinder to the device while soldering. None of the dimensions are critical. As built, the base give clearance of 3.5" from the hold-down tip to the screw-eye, so it's capable of soldering SMDs on a PCB up to seven inches wide. The dimensions can be altered to suit.

I've enclosed a few pics and a rough sketch.

Hope that's of interest and help to someone.

I use the "tin one pad, a bit of flux, reflow with component held in tweezers and then solder other end(s)" method. Very quick. Doing hand soldered SMT stuff flux is your friend.

[Goldieoldie]

I use tiny amounts of blue tac to position the smd.Also works well with larger Elec Ali smd caps as you can hold in position by bridging with tac between the cap and another component
Cheers Pete

[Radio Wrangler]

I've seen lots and lots of hold down jigs for SMT components, but I've never used one and I've built a lot of SMT stuff. Tweezers, like Merlin, do it for me.

David

[Nickthedentist]

Another handy project, David, thanks for posting.

[Ti Pwun]

There have been a few times when I could have used one of those, that's for sure. Very nicely made, too. I've used tweezers, Kapton tape, White Tac and just a heat hardened finger end if I'm not using the reflow oven but I do like that jig.

[Herald1360]

Tweezers to position the device, then a scalpel (10A blade) to hold it down whilst doing the one pin reflow then solder the rest. For pins at less than 50 thou spacing, the flood and solderwick technique works well.

[Ti Pwun]

...and a needle oiler full of liquid flux!

[David G4EBT]

Not having any experience in the use of SMDs, (nor possessing the desire to acquire such experience!), looking at the diminutive dimensions of SMDs, I've probably made the tip rather too large at 3mm diam, so the equivalent of a ball point pen tip would doubtless be more useful. I'm sure my chum will overcome that by filing the tip to a point if need be. Resistor dimension v Wattage is here:

http://www.radio-electronics.com/inf...d_resistor.php

More dimension info on a range of SMD components here:

http://www.topline.tv/SizeChart.html

I guess that in time we'll all be funnelled into the need to use SMDs for homebrew projects due to the non-availability of wire-ended components, especially semiconductors.

[Tyso_Bl]

Very nicely finished, has it been used yet? Would there have been any benefit in using a pantograph type arm?

nor possessing the desire to acquire such experience!

Once over the 'fear' of SMD it is great for homebuilt stuff, no need to drill the PCB except for ground planes and the odd link. When I started SMD work I thought an 0805 (80 thou by 50 thou) resistor was small now I am happy soldering 0201 components. Although for home made PCBs I don't go below 0603 passives and 0.5mm pitch ICs.

[David G4EBT]

Originally Posted by Tyso_Bl

Very nicely finished, has it been used yet? Would there have been any benefit in using a pantograph type arm?

Thanks for your kind comment.

No, it hasn't been used yet - my chum is awaiting a kit to arrive.

A pantograph arm would certainly be more elegant in terms of the arm remaining vertical when lifted and lowered, but the tip will only be raised about 5 - 10mm or so, and hence won't far out of vertical when placed on the component. The vertical arm with the tip can also be adjusted by hand if need be, as it's not rigidly fixed to the horizontal arm at the top.

If it were to be in constant use, there would certainly be scope for an improved design, but I'm hoping that when my chum gives it a 'test drive', it will fit the bill for now! That said, feedback from forum members who are experienced in SMD construction indicates that they find little need for such a gadget. From videos on YouTube, I'm amazed at how resilient SMDs seem to be - some are soldered by applying solder paste, placing all the SMDs on the board, then using a hot air gun to melt the solder - others place the board in an oven, and so forth.

[robin coleman]

I tack one end first and then apply flux using a flux pen and solder the ends. I have also applied hot melt glue with a darning needle (just a bob) to hold the component down while soldering. Weller did a hollow tip which acted like a reservoir to apply the solder.
Regards
Robin

[GeoffK]

The jig could be useful, though the component, if it is a multileg chip, would still have to be positioned first and clamping might cause it to move. I don't know if static charge could develop on the wood though the operator should be wearing an antistatic wristband and working on a conductive surface if chips are being soldered.
I have reworked lots of surface mount chips when working for a diode laser company. When fitting the new chip or component I used Multicore solder wick to remove solder after cutting off the faulty chip to give a flat pad surface. Then carefully align the new component and hold it down with cranked tweezers and tack solder a couple of legs or one end of the component with the solder that was left on the pad, then leave it for the pads to cool before applying the finished solder to reduce the risk of the solder pad lifting.