How to prep solder pads? [Archive] - The Custom Saber Shop Forums

Dakarn

01-23-2010, 07:02 AM

Ok I did some searching and I found some information about prepping pads on LED stars - basically it stated to rough up the pad with an Xacto knife. I had a problem tinning a Cree last night because the solder wouldn't flow onto the pad. Finally got it to happen but it was an effort and I really thought I harmed the pad, which I didn't - now Consilium Laurus is Green. :)

What I was wondering is what to use to prep the pad? Swab them with alcohol prior to scoring them to clean off any coatings?

xl97

01-23-2010, 07:49 AM

Dakarn

01-23-2010, 08:23 AM

I have never heard of anything liek you are saying.. to prep any type of connection (pads/wires..etc)

you do what is called 'tinning' them..

that is put a little smear/dab of solder on the pad..."AND" on the wire ends... BEFORE you try to solder them together...

If you go to wwwplecterlabs.com and look at tuorials/vids.. it outlines this process for you.

The issue I was having is that the Cree wouldn't take the smear/dab of solder on the pad. I've reviewed Erv's videos on soldering extensively and believe me, it took a good half hour of effort to tin those pads last night. No problems with tinning wires or otherwise just with this pad.

xl97

01-23-2010, 08:36 AM

it wasnt on a heatsink by chance was it?

Dakarn

01-23-2010, 08:38 AM

it wasnt on a heatsink by chance was it?

Actually I started with it on the heatsink then after about a minute it dawned on me. So I took it off, put it on my work pad and was still had issues getting the solder to stick to the pad.

cardcollector

01-23-2010, 08:40 AM

The pad needs to be as hot as the solder the monment the two come in contact, that way the pad will "accept" the solder.

It is tricky though because you don't want to kill the led...

Practice is what I reccomend, once you get the hang of it it is like riding a bike...

you never forget.

Sidd

01-23-2010, 08:41 AM

The issue I was having is that the Cree wouldn't take the smear/dab of solder on the pad. I've reviewed Erv's videos on soldering extensively and believe me, it took a good half hour of effort to tin those pads last night. No problems with tinning wires or otherwise just with this pad.

You dont need to take offense to people trying to help you, thats a quick route to not getting help at all.

Maybe there was some kind of residue on the pads from the manufacturing process that was left by accident

cardcollector

01-23-2010, 08:44 AM

xl97

01-23-2010, 08:52 AM

I didnt think he had an attitude at all...

anyways-

as CC says..maybe the pad isnt hot enough yet... what size soldering iron are you using?

I have heard of this a few other times about a certian LED being hard to solder too.. dont recall if it was the CREE's or not though...

Dakarn

01-23-2010, 08:54 AM

cool it Sid, don't pick fights. He was just verifying that he had already done that...

also, about the residue-that's a good point- I had to very lightly sand the pad because of a residue that kept melting and mixing with my solder.

Oh yeah....
Can we see the new CL in green!!!

Phoenix had a good point in chat - the iron may not be powerful enough to apply enough heat fast enough. But there was a coating of some sort because there is residue on the star.

Also, Jaygon had a similar issue:
http://www.fx-sabers.com/forum/index.php?topic=18790.msg286329#msg286329

Photos of the new CL in green tonight, I'm liking the new look.

Sidd

01-23-2010, 08:55 AM

cool it Sid, don't pick fights. He was just verifying that he had already done that...

also, about the residue-that's a good point- I had to very lightly sand the pad because of a residue that kept melting and mixing with my solder.

Oh yeah....
Can we see the new CL in green!!!

I wasnt starting a fight, if I was I am not that subtle lol

you might also want to get a tiny set of files to keep on hand they are great for stuff like that, I know I use mine all the time

Nineteen

01-23-2010, 01:20 PM

I had a similar issue with my Cree. I just used a bit of sandpaper to rough up the pads, and it turned out fine.

thejedilestat

01-23-2010, 03:00 PM

out of the 5 leds i have this problem only happend to me with one of the pads on my white p4 but after the 3rd try it worked like normal

i have never used a Cree

Damin Kestler

01-23-2010, 03:01 PM

There's a trick to Soldering that not many people know about.
Solder Flux!
You can get it from Radio Shack or Home Depot.
http://rsk.imageg.net/graphics/product_images/pRS1C-2110791w345.jpg

Soldering Flux is formulated to remove the oxides from the metal and make the Solder and Metal more able to combine when heated.

Just add a bit of Flux to anything you are about to Solder, (Tinning Leads, Prepping Pads, Ect), the Solder will flow much better and you will get a clean bond.

Also...if you use a Rosin Core Solder...that will help also.

Good luck!

Dave
AKA: Damin Kestler

cardcollector

01-23-2010, 07:48 PM

Solder paste is great too!

It acts like a glue after being heated to the melting point of solder.

Obi-Dar Ke-Gnomie

01-24-2010, 02:16 PM

Here's why some LEDs are harder to solder than others. The one on the left is a Lux III, and the one on the left is a K2. You can see that the Lux III has a layer of PCB material that acts like an insulator for the solder pads, so the heat stays there. On the K2, and some other LEDs, there is no PCB layer, so the heat gets sucked away by the aluminum backing plate.

All you can really do, is make sure you have a good hot iron, to get the solder pad hot quickly.

http://i238.photobucket.com/albums/ff102/dar4jc/100_2308.jpg

Dakarn

01-24-2010, 05:43 PM

Thanks to everyone for their advice. I have a new, hotter iron station on its way so hopefully that'll solve the issue. Plus with the tips here I now know a bit more about how to handle the situation when it happens again.

dad

02-02-2010, 02:05 AM

use resin core solder, wipe the solder with a bit of tissue to clean off any surface crap. A new thing to note, lead-free solder needs a higher temp than tin-lead solder, so watch what you buy.

Make sure the iron is hot, apply a little solder to the tip then put the tip on the pad and apply the solder to the tip where it touches the pad, then move it to the pad, wait until the solder moves/flows across the pad and take the solder then the tip away. In real life you would wipe the tip on a damp sponge, re-tin it with solder, tin the pad, then wipe the tip on the sponge again. Resin or rosin is an acid and letting it stay on a solder tip lets it eat the iron plating on the tip, and it then 'pits'. /2c