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Sinister_Y
2009.12.08, 10:12 AM
Hi,

Looking at a soldering/de-soldering workstation and don't have a FET handy from one of the boards. Does anyone know what the measurements (dimensions) are of the FET? I'm interested in the terminal side of the FET, i.e. where the legs get soldered to the board. What is that max distance between the 1st and 4th leg?

The choices for a desoldering tweezer tip is 3mm or 6mm. I'm thinking the dimenions is between 3 and 6 mm but wanted to ask someone to validate.

Thanks!

Action B
2009.12.08, 10:39 AM
Hi,

Looking at a soldering/de-soldering workstation and don't have a FET handy from one of the boards. Does anyone know what the measurements (dimensions) are of the FET? I'm interested in the terminal side of the FET, i.e. where the legs get soldered to the board. What is that max distance between the 1st and 4th leg?

The choices for a desoldering tweezer tip is 3mm or 6mm. I'm thinking the dimenions is between 3 and 6 mm but wanted to ask someone to validate.

Thanks!
I can measure one of my FETs off the board for you, however, I've done dozens of FET jobs and never used one. Byebye on this forum has shown me a method for FET removal that I swear by. All you need is a 10 dollar soldering Iron from Wal mart. I've never lifted a single pad or had one dead board.

Everyone I've seen try to lift up on the legs and desolder them individually, or that use any lifting on the FET at all during desoldering has had lifted pads from it.

Lol actually I can't find a ruler....

ianc
2009.12.08, 10:46 AM
Byebye on this forum has shown me a method for FET removal that I swear by. All you need is a 10 dollar soldering Iron from Wal mart. I've never lifted a single pad or had one dead board.

So is this a big secret, or did you plan to describe it for us, or better yet post a tut with pics?

ianc

Action B
2009.12.08, 10:49 AM
So is this a big secret, or did you plan to describe it for us, or better yet post a tut with pics?

ianc

He has a video. He made it for the forum so I don't think he'd mind if I reposted it. Let me host it somewhere.

I have some stuff I could add for a tutorial though about testing continuance to be certain the pad is properly installed before powerup. I modified his technique slightly as well to my own liking.

Action B
2009.12.08, 11:06 AM
Byebye FET video part 1 (http://www.flickr.com/photos/32837163@N02/4168751011/)
Byebye FET video part 2 (http://www.flickr.com/photos/32837163@N02/4169514202/in/photostream)

Notice, the secret to this is that he never lifts vertically on a single FET. Its hard to lift a pad when you don't lift at all!

And such groovy music! You'll be learning in style!

Also, I use a maddell soldering station with adjustable temperature, soldering braid to clean up the fet pads after removal and silver bearing solder from Radio Shack. Oh yeah, and helping hands in case the board is not in the car.

Of course, those things aren't necessary as you can see from the video, they just are nice to have. A wal mart soldering iron will do just fine.

Sinister_Y
2009.12.08, 11:24 AM
Thanks for the info Action B.

Maybe one of the moderators can sticky the videos somewhere?

Still thinking of getting the system though. I love toys and it's cool:

http://www.cooperhandtools.com/brands/cf_files/model_detail.cfm?upc=037103215178

Action B
2009.12.08, 11:49 AM
Thanks for the info Action B.

Maybe one of the moderators can sticky the videos somewhere?

Still thinking of getting the system though. I love toys and it's cool:

http://www.cooperhandtools.com/brands/cf_files/model_detail.cfm?upc=037103215178

They really DO need to be stickied. I taught myself how to do FETs just through these videos.

Another thing, If you like that toy you might like MY toy. I find it works great for FET installation.

Click HERE (http://www.ntscope.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=MTC&Product_Code=AT201D&Category_Code=RS)

Sinister_Y
2009.12.08, 11:54 AM
Nice...

Got a friend though with a crazy system at his work. His station is worth over 4k. It has both soldering and desoldering capability. It has a vacuum built in to suck up the solder when desoldering. It also has auto-feed on the soldering iron. When I smoke my FETs last week on the rental AWD, he fixed it, but I don't want to keep asking for favours. Also, thought since I've got the track open now, should be able to offer FET upgrade to everyone.

Action B
2009.12.08, 11:57 AM
Nice...

Got a friend though with a crazy system at his work. His station is worth over 4k. It has both soldering and desoldering capability. It has a vacuum built in to suck up the solder when desoldering. It also has auto-feed on the soldering iron. When I smoke my FETs last week on the rental AWD, he fixed it, but I don't want to keep asking for favours. Also, thought since I've got the track open now, should be able to offer FET upgrade to everyone.

Yeah, that sounds like an intense rework station. They use some intense ones in the Navy too from what I understand.

I learned how to do FETs in order to do them for my own club. So far so good but I haven't got to try my skills on a 2.4 board. I've heard they are easier to lift pads on so I'm looking forward to getting ahold of one and try it out.

ianc
2009.12.08, 12:09 PM
Thanks for posting the vids!

ianc

Action B
2009.12.08, 01:47 PM
Thanks for posting the vids!

ianc

Yes, Of course. Also a very special thanks to Byebye.

JeremyC
2009.12.08, 02:23 PM
Byebye FET video part 1 (http://www.flickr.com/photos/32837163@N02/4168751011/)
Byebye FET video part 2 (http://www.flickr.com/photos/32837163@N02/4169514202/in/photostream)

Notice, the secret to this is that he never lifts vertically on a single FET. Its hard to lift a pad when you don't lift at all!

And such groovy music! You'll be learning in style!

Also, I use a maddell soldering station with adjustable temperature, soldering braid to clean up the fet pads after removal and silver bearing solder from Radio Shack. Oh yeah, and helping hands in case the board is not in the car.

Of course, those things aren't necessary as you can see from the video, they just are nice to have. A wal mart soldering iron will do just fine.

In order for this method to work you have to get the chip and board very hot; so hot that the solder will stay hot while you move the iron to the other side. In general that is not good for the IC or the board; and the machine Sinister_Y is looking at will be much easier to use. I would also argue that you can still lift pads using this method; as the traces are getting very hot and the metal is much more malleable when hot.

If you use this method you must be careful to not push too hard; you must wait for the solder on both sides to be warm enough to easily remove the IC.

Since you are throwing away the IC's that you are removing the heat isn't such a big deal, but I certainly wouldn't steer someone away from buying a proper IC removal tool.

I prefer to use small wire clippers and clip all the legs off the IC, the IC itself will fall right out. Then remove each leg with the soldering iron. You must clip one leg at a time because if you try to do two or more, you are putting force on the pads.

-Jer

FWIW I am an amateur radio operator and have built a few two way radios, antenna analyzers, tuners, and a lot of other random homebrew electronics.

Action B
2009.12.08, 04:06 PM
In order for this method to work you have to get the chip and board very hot; so hot that the solder will stay hot while you move the iron to the other side. In general that is not good for the IC or the board; and the machine Sinister_Y is looking at will be much easier to use. I would also argue that you can still lift pads using this method; as the traces are getting very hot and the metal is much more malleable when hot.

If you use this method you must be careful to not push too hard; you must wait for the solder on both sides to be warm enough to easily remove the IC.

Since you are throwing away the IC's that you are removing the heat isn't such a big deal, but I certainly wouldn't steer someone away from buying a proper IC removal tool.

I prefer to use small wire clippers and clip all the legs off the IC, the IC itself will fall right out. Then remove each leg with the soldering iron. You must clip one leg at a time because if you try to do two or more, you are putting force on the pads.

-Jer

FWIW I am an amateur radio operator and have built a few two way radios, antenna analyzers, tuners, and a lot of other random homebrew electronics.

I've done over 25 boards with this method, it has never failed me yet. I would steer people away from a $300 dollar kit if all they want to do is FETs, because, frankly, its not necessary and its saving them money. We can talk about whatever hypothetical reasoning, however, I've done it over and over again. That is what really matters. I also frequently re-use the mosfets removed from the boards in this manner. I understand your reasoning here and I may not have the experience you do so I'm not saying I know more or anything. I guess the person deciding to start doing FET work will have to decide who they agree with on this one.

Also, your supposed to use a low wattage soldering iron.

ianc
2009.12.08, 04:38 PM
I prefer to use small wire clippers and clip all the legs off the IC, the IC itself will fall right out. Then remove each leg with the soldering iron. You must clip one leg at a time because if you try to do two or more, you are putting force on the pads.

I like this method and have used it in the past. It prevents too much heat buildup on the board itself which can actually desolder surrounding components. The 2.4 boards are particularly vulnerable to this because of the high density of the components on the board.

There are only two problems with the clip method: You've gotta have some pretty small clippers, and you can't reuse the FET afterwards. Since I've only ever replaced blown or suspect FET's, not being able to reuse them has not been an issue for me...

ianc

Action B
2009.12.08, 04:49 PM
I like this method and have used it in the past. It prevents too much heat buildup on the board itself which can actually desolder surrounding components. The 2.4 boards are particularly vulnerable to this because of the high density of the components on the board.

There are only two problems with the clip method: You've gotta have some pretty small clippers, and you can't reuse the FET afterwards. Since I've only ever replaced blown or suspect FET's, not being able to reuse them has not been an issue for me...

ianc

Well I haven't tried it on a 2.4 board yet. I can't say for sure it would work or not. I'd try it on mine honestly if I had one.

Sinister_Y
2009.12.09, 09:15 AM
Has anyone been able to measure a FET? I have a FET at home, but all my measurement tools are at the track.

Guess I will need to wait until Friday when we race to do the measurement.

benmlee
2009.12.09, 03:52 PM
Has anyone been able to measure a FET? I have a FET at home, but all my measurement tools are at the track.

Guess I will need to wait until Friday when we race to do the measurement.

FETs are industry standard SO-8 package. This might help.

http://www.fairchildsemi.com/products/discrete/pdf/soic8_dim.pdf

But instead of getting an expensive desolder station, you can just get two radio shack solder iron and heat both sides at the same time, then pick it up with the solder iron. Just like using a pair of chopstick.

Sinister_Y
2009.12.09, 04:26 PM
thanks Benmlee :)

that was exactly what I was looking for. :D

Action B
2009.12.09, 05:02 PM
I guess my measurement I just took of approximately 4.5mm is no longer necessary...

pedrocamp
2009.12.09, 05:33 PM
I have to vouch for Ben's chopstick method, I have done it on numerous AM and 2.4 boards with no lifted pads, just be patient.