Keyboard modding preparation questions

[Penguin81]

Hi geekhack,

After reading though all the posts I have found about modding keyboards, I still have a few questions I was hoping someone would help me with.

I have a Filco Majestouch-2 with Cherry MX Red Switches and a Ducky DK 9008-G2 with Cherry MX Brown switches.  I would like to swap the switches on the two boards, resulting in a Ducky with all Red switches and a Filco with all Brown switches.

I bought a practice board and successfully desoldered, re-soldered, and verified the keys work on that board without much problem, so I feel confident about the process of swapping the switches.

My questions are these:

What type of solder should I use?  I’ve been reading about leaded vs lead-free solder and given the easier use of leaded solder that seems like a good way to go.  I was trying to decide on the correct mix, whether 60/40 or 63/37, but saw what seemed to be indications that these mixes will dissolve gold.  Are the Cherry contacts gold plated?  If so, will using these solders pose a problem?  Is lead-free that much more of a problem to work with?

Is there a known correct temperature setting? If I was practicing using 850 F without burning the board, does it matter?

What diameter solder would be best?  Should I get the finest diameter I can, making it easier to put the correct amount of solder on the joint?

Should I get solder with or without a flux core?  The solder I was using had a flux core and left a small amount of pooling around the joint, which I don’t think is a problem, but I just want to check.

Lastly, does anyone have any information on or know how I can determine the voltage of LEDs on the Ducky keyboard?  I was considering replacing the blue LEDs with red ones while I was working on it, but saw posts about how changing the voltages on the board may lead to problems with too much draw and such.  Changing the LEDs isn’t a huge deal, just something I considered.

Thanks for the help.

[Penguin81]

Hey Ripster, thanks for the quick reply.

Your guide and many other geekhack threads were definitely the start down the modding road for me, and were what I used to generate my questions.

I re-reviewed the threads you mentioned, but didn't see specific answers to the soldering questions I had.  I did see a mention in the Soldering/Desoldering guide about having a preference for 0.030" 63/37 rosin core solder, but did not see anything about potential problems with dissolving gold.

I do concede that most of questions are probably "over-thinking" the situation, but I am mostly just looking for experiences or any additional input before I start, just to be sure.

Thanks again.

[alaricljs]

As long as you aren't cracking the switch open and tinning the contacts then you shouldn't be worried about soldering the switches.  Try to remember that the Cherry MX design was around before RoHS and lead-free solder.  Solder and flux preference are entirely personal choices when you're not mass-marketing your stuff.  Whatever you can get to work for you is right.

[The Solutor]

What type of solder should I use? I’ve been reading about leaded vs lead-free solder and given the easier use of leaded solder that seems like a good way to go. I was trying to decide on the correct mix, whether 60/40 or 63/37

Usually 63/37 is the bestest, but 60/40 is more than enough for such low technology things...

but saw what seemed to be indications that these mixes will dissolve gold.

Gold is usually meant to avoid protect terminals and connectors from the oxide, when a terminal is soldered it's the solder that protect it, you couldn't care less if the gold is still in place or not.

Is there a known correct temperature setting? If I was practicing using 850 F without burning the board, does it matter?

It depends from various factors, first of all the quality and the power of soldering iron/station, the dimention of the object meant to be soldered, the flux quality and so on.

350/360 C is usually a good stating point, then the experience will tell.

What diameter solder would be best? Should I get the finest diameter I can, making it easier to put the correct amount of solder on the joint?

If your keyboard has just the switches to solder (two large pins), something between 1mm to 1.2mm should be the best choice, on backlit or PCB mounted keyboards (two large + two small pins) , where you have to solder something smaller, 0.8mm could be better, but anyway is matter of personal preferences

[Penguin81]

Hey guys.  Thanks for the input and the welcome.

I finally got the replacement switches I was waiting on, so I decided to start.

Getting into the Ducky reveals that they are probably using lead-free solder, since it is taking longer to melt the solder, and it is generally harder to work with.

This leads to the problem of not being able to get enough solder out to pop the switch free.  I've tried both a solder sucker and a solder braid, but neither is proving fully effective.

Attached is a pic of what I'm left with.  Any suggestions on how to proceed?

Thanks.

[ Guests cannot view attachments ] 20567[/ATTACH]

Update:

2 hrs later I've gotten 10 switches out.  One part of the trick was that the switches were also held to the plate with latches on the bottom half of the switch case.  Another part was to use the iron tip to slowly remove the last bits of solder until the switch started to wiggle.

I have managed to break one switch contact, but that's easy to replace.  My bigger concern at this point is that on two of the switch througholes I seemed to have pulled the collar or lining out.

I've attached pics to try and clarify.

Is this a huge problem?

The following is a side shot of the thoughole, where you can see light coming through the board at key position 5.  Other holes don't have this transparency to them.
[ Guests cannot view attachments ] 20576[/ATTACH]

The following is what the switch looked like after removing it.  What I believe to be copper sleeve lining is still attached to the switch contacts.
[ Guests cannot view attachments ] 20577[/ATTACH]

Sorry for the massive pics, I just wanted to get as much resolution for clarity as possible.

[The Solutor]

You must use fresh solder before remove the older one.

You should even in electronics soldered with the old style solder, but is mandatory if your board is soldered with the lead free alloy.

[Penguin81]

Hi Solutor, thanks for the input, but I'm not sure I fully understand the procedure you are describing.

Are you saying to put leaded solder onto the existing lead-free solder joint and then try to solder suck it away? Do you just put a little bit and then heat the entire pile or what?  Does the new leaded solder somehow attract the old lead-free solder, making it easier to remove?

Thanks for any clarification you can provide.

[alaricljs]

Add solder to the iron, apply the iron to the joint.  The already liquid solder will aid in heat transfer to the solid solder, the increased thermal mass will also keep it all liquid a bit longer as well.

Unless you want to spring for a hot air rework station  

[The Solutor]

Add solder to the iron

No, NEVER DO THIS, it's in the first chapter of the solder's constitution :happy:

Always melt the old solder BEFORE, then add the tin wire to the melted solder.

 When soldering, heat the pin and the soldering island and then apply the soldering wire to the the island/pin while the soldering iron's tip is still touching them.

Are you saying to put leaded solder onto the existing lead-free solder joint and then try to solder suck it away?

Yes, do a first pass to the whole keyboard like you were during the soldering phase. Then heat the island again and quickly use the sucker to remove the melted tin. When/if you find some stubborn places, repeat the process again, add fresh solder and then remove it.

I hope it helps even if written with my poor English.

[sordna]

It's rather hard to remove solder completely. You remove as much as you can, and often still need to pull the component while heating the remaining solder with the iron at the same time.

[Penguin81]

Solutor, thanks for the clarification.  The misunderstanding comes solely from my novice soldering abilities and I thank you for your input.

Ripster, yeah, I figured this was a bad thing.  I was certainly trying to avoid it, but it happened, so I’ll just continue harvesting brown switches and take this a lesson.

I think part of the issue was that my friend and I turned up the heat on the iron to see if we could get the solder to stay melted long enough to suck more out.  This may have contributed to the weakening of the sleeve and pad attachment to the board.  It definitely seemed to happen more near the end of trying this out.

In reading more about removing lead-free solder I came across concerns about mixing lead-free and leaded solder.  Does anyone have an opinion on this?

Even if I tried to resolder with lead-free solder, I have no way of knowing exactly what they originally used, correct?  This would lead to a solder mix anyway, so is it such a big deal or should I really try to go lead-free with a lead-free original?

[The Solutor]

Even if I tried to resolder with lead-free solder, I have no way of knowing exactly what they originally used, correct? This would lead to a solder mix anyway, so is it such a big deal or should I really try to go lead-free with a lead-free original?

No problem, use a leaded alloy, they mix nicely as most of both the alloys is still tin.

[Pylon]

Also don't ever use excessive force to pull a component, especially when you haven't removed all your solder. If it won't budget don't pull on it hard. You'll rip the solder pads and traces right off the PCB, which is a pain to fix especially if you have tightly packed traces.

[bpiphany]

I had a lot harder time de-soldering the switches on a two-sided PCB than on a one-sided. My idea is that the tolder spreads more into the hole and onto the other side. It didn't come out nearly as easy when I tried to suck it. I pulled a few through-plating-copper-thingies as well. I wont be reusing that board though so it doesn't really matter to me. I think it is probably possible to add enough solder into the hole to connect the pin to the back as well. Just reheat and apply more/test the connectivity.

[martinmeijerink]

When desoldering, it becomes a lot easier when you add a little solder, then it flows thoroughly, and this makes it easy to suck all solder at once (with a desoldering pump), this is the result:

[bpiphany]

So am I going to have to desolder another board to try this trick out... I think so =) Perhaps my desoldering pump isn't top notch either.

[Penguin81]

Hey guys,

Just a little update.  Despite screwing up the board straight away, everything went much more smoothly from there on out.  Here are some things I discovered/worked out from GH suggestions

- I ended up running about 700F on the iron and had no problems in terms of taking too long to melt/wet or being too hot and burning stuff.

- Adding solder was absolutely key.

- After the second sit down working on this, I was able to get a clean desolder about 90% of the time.  Part of the issue was to wait just a few seconds longer than I thought, to let the entire pile of solder melt.  Don't solder suck right away, otherwise you'll get that problem where the bottom part of the pile is still there.  If that happens, don't hesitate to completely resolder the joint and start over.  After doing it a few times, you can actually watch the pile wet and can tell when the deeper stuff has gone too.

- At first I avoided using the bulb sucker cause it was too hard to keep in place.  I found that the trick was to place the tip OVER the protruding switch stem.  This keeps the tip where it needs to be when you release the bulb, and pulls a lot more from the joint.  The only downside is that it starts to melt the tip, but these things are cheap and it's well worth the effort it saves.  Keep an appropriately sized drill bit or punch handy so you can remove solder or obstructions from the airway.  Clean it often.  Any obstruction to the air path causes the bulb to become much less effective.  This tip over the stem also works with a spring loaded solder sucker.  Same problem with melting the tip, but much less cleaning needed to keep it functional.

- I had to get creative when removing the LEDs from the Ducky as they were much harder to completely desolder.  A little pull on the keys as I applied heat was necessary for most of them and required some odd positions to support everything, but it worked out.

- Don't pull/pry on cold joints.  That was I did on the first few keys and it worked, but as soon as there was too much solder, I ended up pulling out a conductive sleeve.  I just couldn't tell between too much solder to break cold and just enough.

I feel like there were some other things I wanted to say about this, but thought these points might be helpful if someone else is trying it out soon.

[The Solutor]

- Adding solder was absolutely key.

You'll never have wrong suggestion from me...

- I had to get creative when removing the LEDs from the Ducky as they were much harder to completely desolder.  A little pull on the keys as I applied heat was necessary for most of them and required some odd positions to support everything, but it worked out.

For the leds, the better way is to not user a desoldering tecnique, at all. Just add fresh solder, melt it heating both terminals at the same time, and pull the ledd while the solder is still liquid, only in a second hpase use the pump or the desoldering wire to remove the solder.