Quick: what's your best desoldering braid/wick tip or trick?

RE: Quick: what's your best desoldering braid/wick tip or trick?

Jan Cumps — Fri, 19 Feb 2021 14:59:50 GMT

Wicking in action. Right after wicking, no clean up.

I'm modifying a PSoC6 kit. I used 420 °C for the hot air to remove a resistor, and 380 °C to wick the pads.

Both times with flux applied:

[View:/resized-image/__size/620x490/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-e3b5c0a6-8c01-4e5c-9399-c7a255bbf6a0/3414.contentimage_5F00_207281.png:620:490]

RE: Quick: what's your best desoldering braid/wick tip or trick?

Fred27 — Fri, 19 Feb 2021 11:20:28 GMT

Has anyone tried using solder wick to fix the worn out brushed on a Scalextric car? I've not tried it myself but I think it would work pretty well.[View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-e3b5c0a6-8c01-4e5c-9399-c7a255bbf6a0/contentimage_5F00_938.png:16:16]

[View:/resized-image/__size/320x180/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-e3b5c0a6-8c01-4e5c-9399-c7a255bbf6a0/contentimage_5F00_207279.jpg:320:180]

RE: Quick: what's your best desoldering braid/wick tip or trick?

cstanton — Fri, 19 Feb 2021 10:55:00 GMT

I've never had any luck with solder wick. No matter the temperature or how much flux I have, it doesn't pull the solder away and I end up resorting to a suction gun or bulb of some kind. Perhaps it's the solder I end up working with? it tends to have this kind of liquid suspension that means it doesn't want to attach itself to anything or be wicked away and ends up sitting there unless it's sucked.

RE: Quick: what's your best desoldering braid/wick tip or trick?

jw0752 — Wed, 03 Feb 2021 02:17:46 GMT

Sorry I didn't get into this conversation earlier but i had a bunch of work fall in my lap and I have not been able to keep up with the forum for the last several days. I almost never use solder wick for its intended purpose. In my work on damaged circuit boards it is used primarily as a replacement for burned power traces. I will cut out the portion of the circuit board that has been carbonized by arcing and heat, I will construct a bridge using the solder wick from a good portion of the board to the other side and then I will fill the hole in the board with epoxy. In some cases where the burn is localized and centered on a via I will start the wick on one side of the board and come through the board at the burn using the solder wick as a via to increase the surface area of contact with the lead that belongs in the previously burned hole. The solder wick than continues on the other side of the board to a good solid connection. Where the wick reconnects with the original traces of the board I will scrape the masking off the original trace that is about 4 times as long as the trace is wide so that once again the conductivity of the bond between the wick and the trace is as high as possible. Fluxing the scraped traces helps to make a good solder joint.

One of the weak spots on many power handling boards are the fuse clips. If the board is relying on vias to pads on the other side of the board for good conductivity these are frequently damaged when the fuse clip oxidizes, heats up, and damages the board. I have found in situations where the board isn't too badly carbonized that I can use the solder wick to come from the pad on the underside, through one hole, across the new fuse clip like a belt and down the second pin hole and back to the pad. This necessitates enlarging the original holes slightly. The copper of the wick and the increased contact area afforded by the belting makes this a very good fix.

John

RE: Quick: what's your best desoldering braid/wick tip or trick?

14rhb — Tue, 02 Feb 2021 13:01:15 GMT

Slightly different topic, sometimes the board is Pb-free and you only have an old lower temperature soldering iron - there's no way that solder will melt. However adding a small amount of leaded-solder to the joint prior to using the braid will work.

RE: Quick: what's your best desoldering braid/wick tip or trick?

Gough Lui — Tue, 02 Feb 2021 04:09:37 GMT

I use plenty of wick in my time, partly because I don't like breadboards so much, so I tend to do everything on Veroboard which necessitates generous use of solder wick when things do go wrong or need modification.

My tips would be -

Don't spread the wick out - keep it bunched together so the capillary action provides the maximum "sucking" power. Buy the right width if you can.

Don't be cheap with the wick - you're probably not getting much wicking action if you touch a partially used segment to the PCB, best to use fresh lengths and have fresh lengths on both sides of the joint to be desoldered to get even wicking action from both sides.
Add additional flux to the wick with flux pen if it doesn't seem to do a great job. This is a bit of a last resort, but as with most wicks, you can expect some burned flux residue to remain and need cleaning off.
Mix the solder with some fresh (possibly even leaded) solder to make it easier to wick at a lower temperature - sometimes you need to go back and forth.
Don't rely on wick alone to get holes cleaned - a solder sucker or a stainless steel pin may well do a better job for the smaller, deeper plated-through holes on multi-layer boards, especially if a stubborn bit of old solder remains.
Apply enough heat with a powerful iron to keep everything liquid - otherwise if the solder partially solidifies during movement of the braid, you could tear off a trace.
Don't apply too much heat, else you will probably melt the wick dispenser and lift traces from the board with the heat alone.

- Gough

RE: Quick: what's your best desoldering braid/wick tip or trick?

fmilburn — Mon, 01 Feb 2021 21:50:26 GMT

I am surprised nobody mentioned a solder sucker. I still use mine at times for through hole. I am wondering what [mention:f80b53cee57c44bc9d7c577d07d7c791:e9ed411860ed4f2ba0265705b8793d05] would say about this subject.

RE: Quick: what's your best desoldering braid/wick tip or trick?

Jan Cumps — Mon, 01 Feb 2021 18:48:47 GMT

Paul Daniels of youtube fame cuts a little piece, and holds it with a pincet. Then drags with the iron on it.

RE: Quick: what's your best desoldering braid/wick tip or trick?

navadeepganeshu — Mon, 01 Feb 2021 18:17:32 GMT

Who else got the solder braid too hot to hold and dropped in the middle of operation?

[View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-e3b5c0a6-8c01-4e5c-9399-c7a255bbf6a0/contentimage_5F00_3.png:16:16]

Touch the solder braid with soldering iron tip gently and drag over it to absorb in the solder while handling SMDs. Else, it may bend the leads(especially LQFP, TSSOP) and damage the component. Here's one of mine which happened so:

[View:/resized-image/__size/251x285/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-e3b5c0a6-8c01-4e5c-9399-c7a255bbf6a0/contentimage_5F00_207274.jpg:251:285]

(Luckily, it was some extra GPIO's left on the MCU)

RE: Quick: what's your best desoldering braid/wick tip or trick?

dougw — Mon, 01 Feb 2021 18:16:05 GMT

The wick I have has pretty nasty flux fumes, so ventilation/air filtering is important.

I sometimes add solder to the joint before wicking - to get the heat distributed and melt everything and get the wicking action started.

It is important to ensure all solder is melted and flowing before starting the process - one way is to heat the joint with the iron and slide the wick down the iron to ensure the joint and the wick are both hot before they come in contact. You need an iron that can keep both the joint and the wick hot enough for the solder to stay molten. Flux seems to help keep the copper from oxidizing, and to conduct heat and keep everything hot.

I use stainless steel needles to insert into "cleaned" though-holes to ensure they can later accommodate pins. The solder doesn't stick to stainless, so the needles can be easily removed after the solder freezes, leaving the right size of hole.

That being said, I am not a big fan of solder wick. It is too messy, often requires more heat than is good for the card, and often doesn't work that well.

RE: Quick: what's your best desoldering braid/wick tip or trick?

Fred27 — Mon, 01 Feb 2021 17:51:28 GMT

I was also going to suggest using more flux, but it seems everyone's on the same page with that one. I have a "shoe polish" style tin of flux that I must have got free with something from China. I drag the braid over the surface of that to get it nicely coated with flux.

RE: Quick: what's your best desoldering braid/wick tip or trick?

genebren — Mon, 01 Feb 2021 17:33:29 GMT

In addition to flux, I find it useful to flex the wick back and forth while apply heat and the solder is fluid. This action opens up the braid and allow the solder more freedom to wick. I also drag the wick to help wipe solder out of the joint/lead.

RE: Quick: what's your best desoldering braid/wick tip or trick?

wolfgangfriedrich — Mon, 01 Feb 2021 16:39:29 GMT

Use more flux, always....

RE: Quick: what's your best desoldering braid/wick tip or trick?

Andrew J — Mon, 01 Feb 2021 16:32:44 GMT

For through hole components, don't bend the leads underneath the board to hold them in place on the top side. That "can" make it more difficult to desolder in the future if needed and the part never stays properly in place when you turn the board over. Instead, keep the leads straight through the hole, place the component on the board on the top side, then hold it place with blu-tac or similar. When you flip the board over to solder, the part will stay put, you can solder then trim the leads so they are straight. Try not to get blu-tac in the solder hole! Any residue on the top side can be removed by dabbing the area with blu-tac - in any case, it is non-conductive.