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I own @ halo
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Discussion Starter · #1 ·
I got a new screen for my cell phone, unfortunately when it arrived one of the soldering points appears to be damaged. All of the points are tinned (word?) but the solder on this one has come off. The point in question is only for the vibrate motor so I don't know that it's vital but it would be nice to have (not as nice as a functioning screen)



I tried to circle the points in question, the old screen is under the new one. The point in question is where the pink wire solders to the board on the old screen. If the copper/tin/whatever came off the board with the solder would it be fixable? Or will I just have to live without vibrate? Any help/advice would be awesome.

Thanks,

Bryce
 

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I own @ halo
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1,128 Posts
Discussion Starter · #2 ·
Also with something this small, what would be a good soldering iron to use? I think I have a 15watt, would that be too hot?
 

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Fucking Zen as Shit
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16,148 Posts
Thats a simple fix

15 watt should be good.

Easiest way is to get the parts lined up, heat the wire end up until the solder liquifies and then touch that to the circuit board.
 

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I own @ halo
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Discussion Starter · #4 ·
Thanks, I'll give it a shot. This crap can be really frustrating. I think I am going to put it down and work on this tomorrow so I don't f it up worse.
 

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Covered in mud...
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Yeah, thats pretty easy fix there. Your small iron will be fine, with a nice fine point.

For reference, I could probably assemble/solder every component on that board by hand in 30 minutes. So its possible to do just by naked eye and a hand iron. We have a lot of fancy stuff, but almost everything I do is still without magnefiers or other aids. See that fine-piece connector up at the top left, we do that stuff by hand, no problem.

Desoldering is the trickier bit, that requires better equipment.

We now are moving to lead-free solder, which sucks.
 

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I own @ halo
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1,128 Posts
Discussion Starter · #6 ·
I got it in and it is working save for vibrate there didn't appear to be anything to solder to, where I was referencing. I'm just going to do without vibrate for a while and if I find a deal on ebay for a beat to hell phone that can't be activated and the screen works and the lens is good I'll pick that up and scramble them.
 

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I own @ halo
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1,128 Posts
Discussion Starter · #7 ·
Yeah, thats pretty easy fix there. Your small iron will be fine, with a nice fine point.

For reference, I could probably assemble/solder every component on that board by hand in 30 minutes. So its possible to do just by naked eye and a hand iron. We have a lot of fancy stuff, but almost everything I do is still without magnefiers or other aids. See that fine-piece connector up at the top left, we do that stuff by hand, no problem.

Desoldering is the trickier bit, that requires better equipment.

We now are moving to lead-free solder, which sucks.
Interesting, what sort of equipment do you use? What's different about the lead free solder?
 

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Covered in mud...
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Interesting, what sort of equipment do you use? What's different about the lead free solder?
Two things are different about lead-free solder. One is it has a higher melting point that the tin-lead solder. So you have to heat the material hotter, which increases the risk for damaging components, and damaging the PCB. Second is the flow characteristics, it doesn't wick as well as tin-lead solder, so it can be harder to get a good joint.

Generally, we we build boards, they are all done with reflow solderng. That is, a stencil is overlaid onto the circuit board, and solder paste is squeegeed through it onto the board. Then a machine places all of the compoennts onto the board. Then it goes through an oven, which heats the paste until it flows and becomes a good solder joint. Tin-Lead solder we run our reflow profile to about 235*C. Lead free requires 260*C, sometimes as high as 300*C. So you have to make sure all of your components, especially plastic connectors which are being reflowed, can handle the higher temp. We've got a problem on one of our chrysler lines right now warping connectors @ 300*C.

For us, we do lots of rework int he lab, where you are taking those mass produced boards, and modifying them. Either fixing something, or changing something for a test that I want to run. There, we use hot air for desoldering most things, with special nozzlees which direct the air to just the pins of the part you want to remove, not the other parts. With the lead free solder, you have to heat things so hot that it can start to delaminate the copper traces from the PCB substrate(either fiberglass or paper, depending on the project). We've taken to mechaincally cutting the legs off components now, instead of desoldering them whole. When you are working with big parts (our current program uses a 208 pin microcontroller), its almost impossible to get enough heat to remove it without trashing the board.
 

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Covered in mud...
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I just bought one of these recently, helped me a lot :p

Usually those are good for doing wires, etc.

I like Pan-a-vise products, they have some special clamps for holding PCBs. At home I use a basic ESD safe weller iron, at work I have two basic wellers, a metcal and a 4 head Pace. We have to keep the irons separate for tin-lead and lead-free operations. I almost always work with just hte naked eye as my eyesight is pretty good. Otherwise, I use a 50x stereo microscope for really critical stuff.
 
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