Newbie here, hey everyone! Need advice on rework station

Community PCB Design
1

Hello everyone, I am so glad I found this site. I plan to spend a lot of time here in the future.

I do a lot of soldering, and hope to do even more soldering in the future. Specifically, I do SMT and through-hole soldering on cell phones, PDAs and MP3 players. However, it would be great to know how to remove microchips from PCB’s and put new ones back on. A lot of times these chips somehow die and need to be replaced. The best I can do at this point is replace the entire PCB.

I’ve been looking at rework/hot air stations lately and am overwhelmed by the different kinds and the functions. I’m pretty new to all this and don’t know what I need or which type to get.

Anyone know what kind of station would be best for SMD removal and replacement on cell phones and MP3 players?

Also, how do you tell a memory chip apart from a ROM chip apart from a CPU chip?

2

aeroz19:
Hello everyone, I am so glad I found this site. I plan to spend a lot of time here in the future.

I do a lot of soldering, and hope to do even more soldering in the future. Specifically, I do SMT and through-hole soldering on cell phones, PDAs and MP3 players. However, it would be great to know how to remove microchips from PCB’s and put new ones back on. A lot of times these chips somehow die and need to be replaced. The best I can do at this point is replace the entire PCB.

I’ve been looking at rework/hot air stations lately and am overwhelmed by the different kinds and the functions. I’m pretty new to all this and don’t know what I need or which type to get.

Anyone know what kind of station would be best for SMD removal and replacement on cell phones and MP3 players?

Also, how do you tell a memory chip apart from a ROM chip apart from a CPU chip?

(no name supplied),

Well…you have ask a question that could potentially save you a lot of money.

Lets examine this from a simple stand point. We know solder is a metal (well combination of a few) that is melted to connect chips to a copper coated piece of fiberglas.

If we are trying to remove a part, all we are trying to do, is melt the solder long enough to lift the part off. Now…there are some important thing to note here. First, we need to have all the legs of that part liquid at the same time. If we do not…there is a very good chance we will lift a pad from the board. This could potentially render the board useless. Second, if we heat the surrounding parts to much, we could kill them from working. Third, when putting the part back on…we need to make sure to solder it well.

There are many systems for removing parts, but I found the cheaper ones work just as good.

I bought a hot air rework station from this link:

h**ps://store.sra-solder.com/index.php

The important thing is controlling the temp of the board. The cheaper systems are probably not as accurate, but if you work with it some…it will work fine.

I’m sure other people will chime in here about how you need a fancy rework station…

There are people reflowing boards with clothes irons…so don’t believe everything you read.

James L

3

Every time I open this thread, Avast! goes nuts! It is finding a virus/worm named “VBS:Malware-gen”, but ONLY in this thread. Could the forum have been hacked? Can a mod check the original poster’s post for a hidden URL (easy to do; I put one in this reply).

[www.somemalwaresite.com](http://www.somemalwaresite.com)

4

MarkS:
Every time I open this thread, Avast! goes nuts! It is finding a virus/worm named “VBS:Malware-gen”, but ONLY in this thread. Could the forum have been hacked? Can a mod check the original poster’s post for a hidden URL (easy to do; I put one in this reply).

[www.somemalwaresite.com[/quote]

That isn’t happening to me. And I’m not savvy enough to put hidden URL’s in. I’m not a hacker.](http://www.somemalwaresite.com)

5

MarkS:
Every time I open this thread, Avast! goes nuts! It is finding a virus/worm named “VBS:Malware-gen”, but ONLY in this thread. Could the forum have been hacked? Can a mod check the original poster’s post for a hidden URL (easy to do; I put one in this reply).

[www.somemalwaresite.com[/quote]

I see the hidden url in your quote…

H**p://www.somemalwaresite.com

I don’t think it has anything to do with the website I put in…but it may. I edited my previous post to take the"tt" outof the address. If it has anything to do with that address…that should fix it.

I don’t know…I will make a post in the support forum. (edit: I did make a post in the support forum for an admin to check it.)

James L](http://www.somemalwaresite.com)

6

Sorry to accuse you, aeroz19. I was thinking about all possibilities. I ran SpyBot and am running Avast! right now. SpyBot found and fixed 70 problems, so it seems to have been on my end. Not sure how it got through in the first place. :shock: Problem fixed, for now…

7

propellanttech:

aeroz19:
Anyone know what kind of station would be best for SMD removal and replacement on cell phones and MP3 players?

Also, how do you tell a memory chip apart from a ROM chip apart from a CPU chip?

(no name supplied),

Well…you have ask a question that could potentially save you a lot of money.

Lets examine this from a simple stand point. We know solder is a metal (well combination of a few) that is melted to connect chips to a copper coated piece of fiberglas.

If we are trying to remove a part, all we are trying to do, is melt the solder long enough to lift the part off. Now…there are some important thing to note here. First, we need to have all the legs of that part liquid at the same time. If we do not…there is a very good chance we will lift a pad from the board. This could potentially render the board useless. Second, if we heat the surrounding parts to much, we could kill them from working. Third, when putting the part back on…we need to make sure to solder it well.

There are many systems for removing parts, but I found the cheaper ones work just as good.

I bought a hot air rework station from this link:

h**ps://store.sra-solder.com/index.php

The important thing is controlling the temp of the board. The cheaper systems are probably not as accurate, but if you work with it some…it will work fine.

I’m sure other people will chime in here about how you need a fancy rework station…

There are people reflowing boards with clothes irons…so don’t believe everything you read.

James L

Oh, you can just call me aeroz. My nickname (based upon my dream college major).

Thanks for answering my post. That link you provided was very helpful as well.

I did some more searching and found that there are also infrared rework stations. They advertise those stations as being more suitable to cell phone repairs. Why is that? What makes infrared heating better? Is hot air good enough?

What temperature does the station need to be set at in order to safely heat the solder? And what if there are plastic components on the board? Will the plastic melt?

And I still need to be able to tell the different kind of chips apart. Is there some standard for that?

Also, say I need a new memory chip. Where would I get it if I wanted to buy a brand new one?

8

aeroz19:
Oh, you can just call me aeroz. My nickname (based upon my dream college major).

Thanks for answering my post. That link you provided was very helpful as well.

I did some more searching and found that there are also infrared rework stations. They advertise those stations as being more suitable to cell phone repairs. Why is that? What makes infrared heating better? Is hot air good enough?

What temperature does the station need to be set at in order to safely heat the solder? And what if there are plastic components on the board? Will the plastic melt?

And I still need to be able to tell the different kind of chips apart. Is there some standard for that?

Also, say I need a new memory chip. Where would I get it if I wanted to buy a brand new one?

Well…lets see

Infrared rework stations are good because they heat things up fast, so the time heating surrounding components is shorter. Also Infrared is a directed heat, and doesn’t spread out like air.

The issue is not the type of device, it is how close the parts are. The closer the parts, the more precise (aiming) of the heat you need. It usually won’t hurt the other parts, but they may move or come off if their solder goes to the liquid state.

Both devices (hot air & infrared) require technique…and your only going to acquire that with practice. If you are working with very tightly spaced parts, I would recommend infrared.

The temperature setting of the unit depends on a few factors. How fast to you want the solder to melt? How much heat to you want to put on the board? What temperature will the solder melt at? What type of solder was used?

There are a lot of variables to that question…I usually start on the low side (temp) and work my way up. If the solder is not melting fast enough…I’ll ramp the temp up some.

Most plastic components were reflowed (baked in an oven to mount them) or they were wave soldered. The plastic electrical components will take quite a bit of heat before you damage them. Just don’t try Dante’s inferno on them.

Different chips should be marked (this is dependent on the manufacturer). They will have a number on top…and you will have to search the internet to find out what the chip is and what it does.

There is not a standard per se for different chips being marked one way or another, nor being one type of chip versus a different kind.

The only standard is they are usually marked with a part number. There is a catch. Just because you find a part number does not mean you will find the chip on the internet. Some companies buy proprietary chips that are only made for them. Those chip part numbers will not be found on the internet, because no one can buy them.

There are ways to overcome this obstacle…but I’m not sure your up to that challenge yet.

If you do remove the chip, and find the part number on the internet telling you what the chip is and does, then you will have to find a supplier of that chip as well. Actually you probably found a supplier when you were searching for the part number.

As you can see…it all not black and white. There is (or can be) a lot of leg work involved to do what you seek. Also…there is a chance you find a situation you can not fix. Don’t worry though, there is a possibility that you have two different phones with two different problems, then one phone becomes a donor.

I hope this helps,

James L

9

propellanttech:
Well…lets see

Infrared rework stations are good because they heat things up fast, so the time heating surrounding components is shorter. Also Infrared is a directed heat, and doesn’t spread out like air.

The issue is not the type of device, it is how close the parts are. The closer the parts, the more precise (aiming) of the heat you need. It usually won’t hurt the other parts, but they may move or come off if their solder goes to the liquid state.

Both devices (hot air & infrared) require technique…and your only going to acquire that with practice. If you are working with very tightly spaced parts, I would recommend infrared.

The parts on the PCB’s I deal with are indeed very close together. I am worried now about the solder on the other components melting and then the components falling off the board or getting loose. But I suppose this can be prevented by using a very fine tip on a hot air gun?

Here is a typical PCB I deal with:

http://www.aerozbooks.com/images/upload … RBOARD.jpg

It is approx 2"x4". Is this small enough/dense enough to require an infrared station? I also regularly deal with PCB’s that are close to 1.5"x2.0"

The temperature setting of the unit depends on a few factors. How fast to you want the solder to melt? How much heat to you want to put on the board? What temperature will the solder melt at? What type of solder was used?

There are a lot of variables to that question…I usually start on the low side (temp) and work my way up. If the solder is not melting fast enough…I’ll ramp the temp up some.

Most plastic components were reflowed (baked in an oven to mount them) or they were wave soldered. The plastic electrical components will take quite a bit of heat before you damage them. Just don’t try Dante’s inferno on them.

Ok, good advice. I currently have a soldering iron that takes about 2 mins to heat up, which is ok. I wouldn’t want any station I used to take longer than that though.

I don’t know how much heat I want to put on the board, or what type of solder was used.

Different chips should be marked (this is dependent on the manufacturer). They will have a number on top…and you will have to search the internet to find out what the chip is and what it does.

There is not a standard per se for different chips being marked one way or another, nor being one type of chip versus a different kind.

The only standard is they are usually marked with a part number. There is a catch. Just because you find a part number does not mean you will find the chip on the internet. Some companies buy proprietary chips that are only made for them. Those chip part numbers will not be found on the internet, because no one can buy them.

Ok, I was really hoping there was a standard; that would be nice. But I have no issues looking them up and writing my own catalog of them as I search.

There are ways to overcome this obstacle…but I’m not sure your up to that challenge yet.

If you do remove the chip, and find the part number on the internet telling you what the chip is and does, then you will have to find a supplier of that chip as well. Actually you probably found a supplier when you were searching for the part number.

As you can see…it all not black and white. There is (or can be) a lot of leg work involved to do what you seek. Also…there is a chance you find a situation you can not fix. Don’t worry though, there is a possibility that you have two different phones with two different problems, then one phone becomes a donor.

I hope this helps,

James L

I am definitely willing to do the leg work. Thats kinda what I am doing here in this forum. :wink:

As for the donor method, I do that a lot already such as for headphone jacks and such. Works out pretty well, and is very efficient. I used to sell off whole PCB’s when they didn’t work but now I’ll be using them a lot more thoroughly. Heh! The only thing that will be left is the fiberglass!

Thanks a lot for all your extremely helpful information. I expect I will be back soon and often.

10

With a tightly poplulated board like a cell phone would have, you are really much better off using infrared. (but this also depends on the following)

Even with a find tip on a hot air gun, the air will spread when it hits the board. This is the problem that you face.

With infrared, the heat is localized to where it “shines” which will reduce the surrounding parts from unsodering theirselves. Notice I didn’t say prevent. We must remember, we are not only heating the pins that hold a part down, we are also heating the board. The board will transfer heat to other components.

There is another situation that we have not discussed, this is QFN type parts. Parts with no legs. (all the connections are underneath).

Infrared is not prone to work very well with BGA or QFN type parts. It is hard to direct the heat far enough underneath the chips to melt all the solder ( you have to rely on the board transferring the heat). This is where hot air will shine. Because air will flow (like water) underneath a chip to melt the solder holding it down.

So now you have to decide what type of parts you are more likely to replace.

Some times there are compromises…

James L

11

propellanttech:
With a tightly poplulated board like a cell phone would have, you are really much better off using infrared. (but this also depends on the following)

Even with a find tip on a hot air gun, the air will spread when it hits the board. This is the problem that you face.

With infrared, the heat is localized to where it “shines” which will reduce the surrounding parts from unsodering theirselves. Notice I didn’t say prevent. We must remember, we are not only heating the pins that hold a part down, we are also heating the board. The board will transfer heat to other components.

The only way to know, I suppose, is to test out a hot air one and see if it will disturb the components. I have to make a decision to purchase a rework station by the end of next month; not a lot of time left.

There is another situation that we have not discussed, this is QFN type parts. Parts with no legs. (all the connections are underneath).

Infrared is not prone to work very well with BGA or QFN type parts. It is hard to direct the heat far enough underneath the chips to melt all the solder ( you have to rely on the board transferring the heat). This is where hot air will shine. Because air will flow (like water) underneath a chip to melt the solder holding it down.

So now you have to decide what type of parts you are more likely to replace.

Some times there are compromises…

James L

Most of the parts that I need to replace have pins sticking out. I rarely see a BGA one. And I suppose if I came across a BGA one, I could put a hot plate under it to help get the solder heated, then just a little bit of infrared heat from above the PCB should do it, right?

I need to see more than a YouTube demonstration of these things. Do you know of some way that I can go watch someone at work, preferably cell phone/pda application? And if they felt really nice that day maybe they’d let me try out my PCB too.

Am I dreaming?

12

Well…to be honest…you hardly ever see a video of the action.

Most people using these are working on boards they don’t want you to see. Also…if they make a mistake…they don’t want a video record of it.

I think you will just have to take “your chances” on which version you purchase.

I know this doesn’t help,

James L

13

I’ve recently got a hot air station. I hope to save up through teh year and get one of the cheaper preheaters (Aoyue or the low-end air bath from someone) and stand/holder for the air gun. But even the cheapest stand/holder I’ve found, the Aoyue one, is rather expensive for what it looks like. Someone on another forum suggested a retort stand (lab equipment) which can be much cheaper. Some say to hack a Dremel stand, but the one I have for my dremel doesn’t seem to have much depth to get to the center of a board without hitting the stand’s pole.

Has anyone tried a desktop microphone stand? The flexy gooseneck style seems it may be too flexy and not hold the gun stable in place. The “scissor” style movable booms look convenient, but I’m not sure they’ll be strong enough to stay in place well. A metal rod boom may be good for stability, but I’m not sure about convenience, as someone mentioning the retort stands said he sometimes had issues trying to move the gun out of the way to pick the chip before it cools off. I’m not sure of a metal rod book stand would be better than that or not. So I thought I’d try to spark a conversation about it.

14

I’m 14 years old and got a Aoyue 852A++ about a month ago, works like a charm. It was about $140 and came with an assortment of tip sizes and a vacuum pickup tool that doubles as the air intake. The airspeed is adjustable really finely and the temperature goes from 100C-480C in 10C increments. A nice lightweight and simple unit with digital readout, a cooldown mode, and automatic shutdown after 5 minutes. Also on the unit is a holster for the gun and a blue-lit airspeed indicator. The handle is nice and big, very comfortable with a wide flexible hose about two feet long.

I’ve done everything from through-hole connectors to tiny passives and every SMD package from SOIC to QFN, even BGA with some patience. A good starting temperature for nearly all the PCBs I’ve practiced on was around 280 degrees and default airspeed. Increase the temperature for quick removal, but as a rule of thumb on large devices you want to slowly preheat all the pins, so all the connections are molten at once (best way to do 120+leaded chips and BGA). As for plastics, you don’t need to worry about them much. For small passives you should use a lower airspeed or they will blow right off the board once molten!

For the kind of work you are doing I think a hot air station would work just fine, just be careful where you point the air and be precise if in tight areas. Once you start practicing you’ll learn pretty quick what temperature and technique works, it’s actually pretty difficult to destroy a PCB unless you stop moving the hot air gun for awhile! Just to give you an idea, I’ve very successfully stripped NVIDIA graphics processors and BGAs in close quarters. Once you use hot air, you’ll never go back to individually unsoldering pins.