I am soldering a 10 lead MSOP (LMH1980) onto a PCB. Or trying to do so. The chip has a pitch of 0.5mm. I find that every time I use the "tack and glob" method I have been taught, I cannot remove the excess solder; it just sticks to the pins. (Tack and glob: pin a few crucial pins down, then glob solder over the pins. Wick away excess solder.) Tack and glob seems to work for a TQFP44 dsPIC and an TSOP16 ADG733 chip, but every time I do tack and glob on the LMH1980 I find that I cannot remove the excess solder, and in the process of trying to do so, I have damaged two PCBs (pulled the pads off) with components already on them. How can I solder this chip? BTW, I have only a basic temperature controlled soldering iron and hot air station (Aoyue 968.) Nothing fancy.
Electronic – How to solder this tiny (0.5mm pitch) MSOP10
soldering
Related Solutions
If you don't want the leads to protrude on the bottom side you essentially want to mount your TH components as SMDs. So I would suggest to use SMD pads, push the leads onto the pads, and solder them there.
For large/heavy components this might give a mechanical reliability problem: a round wire soldered at both sides (or soldered at the bottom only but with a component immediately at the top) can't easily rip the copper from the PCB, but a lead soldered to an SMD pad can!
PCB material is not optimized for conducting heat, so you might want to put lots of via's in the appropriate places to conduct the heat.
I read in your edit that you want to do this for trough-hole screw connector blocks. My gut feeling is that this will seriously impact the mechanical reliability. You could consider using those two-level connectors for screw terminals, which would free room so you could put your heatsink under only a part of your PCB, leaving the area of the screw terminal terminals to be soldered at the bottom.
In looking at your picture, I'd say it looks like to me that:
- Your wires are too long (too much insulation stripped)
- Your wires don't appear to be adequately tinned
- You appear to have stripped the wires with a pocket knife or similar (shouldn't impact solderability, but looks bad and may contribute to #1)
- It doesn't look like you twisted the wires together before you tinned them.
In general, I squeeze wire strippers on the insulated wire to cut through the insulation, then twist the cut end as I pull it off to get a tidy twisted end, like this (though that's a lot longer than I would generally ever expose)
Once that's done, I coat the neat wire end with a copious amount of flux, then get a gob of solder on the tip of the soldering iron, then lay the gob on the wire until the solder is wicked into the wire. No need to rub the iron on the wire, or press, or do anything else - it'll all get soaked up as soon as the wire gets hot enough.
Once that's done, keep adding solder until right at the point you can barely distinguish the original stranding. At this point, the wire's tinned. If you tin the pads with a **little* solder, then soldering the two parts together should just involve laying the soldering iron on the wire with the wire on the pad.
You shouldn't ever need to push or rub or poke with the iron. Be sure to clean the tip off with a damp sponge immediately before you do any work.
If you're looking to get a solder joint like the one below, check out this tutorial on tinning wires and this tutorial on soldering to LED strips.
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Best Answer
Flux!
Solder bridges mean you need more/better/fresh flux.
(Either iron or hot air will work fine. Heat is heat. I prefer iron for clearing shorted pins: wipe iron on sponge, apply to pins, repeat. The excess solder will stick to the tip.)