Circuit Board clean up question.

[gpatel_uk]

I've just taken out a large IC from a plasma Y board. It took a while as the solder would not melt. So I had to keep using flux and add new solder. This melted the old solder and finally I got the part out!

The problem I have is when you look under the board some of the pin connections are merged together (as shown in the photos, I guess from me moving the pins back and forth with the soldering iron. So scratched the top surface off). On the top of the board all the pin connections are separate and look clean.

The second photo I've not properly cleaned yet but again a problem I have is the solder in the hole of the pin connections. How do I get those out. I've tried a twisted copper braid and it worked for some but not all.

I notice that where the connections are merged they are grouped by the lines on the board.

Anyhow what I want to know is have I messed it up? Or will it be ok?

Thanks.

 

[davenn]

hi there

ahhh the fun of removing solder from large earthplane areas.
turn up the heat "my son" turn up the heat
large groundplane areas like that really need lots of heat to clean up then using solder sucker/ desoldering braid will be easy
Also buy yourself a spraycan of flux remover to clean up the board after all the de-soldering, it really makes it all look good

cheers
Dave

 

[CocaCola]

As Davenn pointed out you need more heat, until you get the solder molten and staying molten you are not going to have much luck...

Once you get the solder hot, you can use a solder sucker to clean the holes, or as I usually do, just give it an abrupt whack on the table, as long as the solder is molten it will fling right out of the holes...

But, none of this is going to happen until you get it hot enough, a heat gun would also do the trick, just be sure to not cook the board...

 

[MrEE]

Here is a technique I use all the time with good success; You need a combination of hot air (a controlled temp and air flow smd hot air gun is best), a soldering iron and a solder sucker. You'll need a third hand or a helper to hold the hot air nozzle pointing at the work area. This hot air will preheat and replenish the heat absorbed by the masses of copper inside the PCB. Now the rest is pretty simple. After about 30s - 1 min, start the usual desoldering process, all while the hot air is blowing. Use flux and maybe a touch of fresh solder as needed. Use a good solder sucker (the long one which is about 12" long and not the small sized ones which are pretty much useless).
You'll need to experiment first to get the right settings of air temp/flow. The PCB should never become dark which means it is getting too hot. (Flux will become dark brown which is ok) I hope this helps.

 

[CocaCola]

Here is a technique I use all the time with good success; You need a combination of hot air (a controlled temp and air flow smd hot air gun is best), a soldering iron and a solder sucker. You'll need a third hand or a helper to hold the hot air nozzle pointing at the work area. This hot air will preheat and replenish the heat absorbed by the masses of copper inside the PCB. Now the rest is pretty simple. After about 30s - 1 min, start the usual desoldering process, all while the hot air is blowing. Use flux and maybe a touch of fresh solder as needed. Use a good solder sucker (the long one which is about 12" long and not the small sized ones which are pretty much useless).
You'll need to experiment first to get the right settings of air temp/flow. The PCB should never become dark which means it is getting too hot. (Flux will become dark brown which is ok) I hope this helps.

If the board is unpopulated the same thing can be done on a $20 cooking skillet, just use a few shims to hover the board just above the surface (if it's not textured) so that you don't get a vacuum lock when trying to suck... And since it's lead obviously don't cook on the same skillet afterwards The skillet is nice as it heats the entire board evenly, you can bring it up to 300° F or so and then the iron will have no problem bumping the temp the rest of the way and you have minimal risk of damaging the board vs a total reflow heat level...

 

[(*steve*)]

Here is a technique I use all the time.

Sounds very similar to a device made by a colleague.

It's a heater blower that he places under his SMD boards. It preheats them to about 125C or thereabouts and makes soldering to large ground planes much easier.

 

[Rleo6965]

One technique that I use was to place the solder sucker on opposite side of pcb and place soldering iron on top side. Once solder already melt solder sucker suck the liquified solder under the pcb and clear the hole.

I also place a 3/8" length of carburator vacuum hose on tip of solder sucker for stronger air vacuum. The rubber hose will not be easily burnt by soldering iron tip.

 

[gorgon]

I used a sharpened match to poke out the solder when melting it from one side. It doesn't suck a lot of heat from the solder and push it aside. It is a last resort, but it works.

This is why you should remember to use thermals when you do PCBs with large filled areas of copper or planes.

TOK

 

[gpatel_uk]

Thanks everyone. I managed to clean nearly all the holes using a solder sucker on one side and the soldering iron on the other. Then the two that didn't suck clean I used a tooth pick.

So all good! Thank you once again.