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Old 26th September 2011, 03:27 PM   #1
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Default soldering a TO-3 transistor technique ? (problem for me)

haha, i'm currently soldering some circuit and it involve a TO-3 package transistor (MJ15003).
Well.... this is the second time i try to solder such package, but both are difficult, as they are hard to wet with my solder (its my solder problem ?) They cannot 'bond' to the surface of it, which easily came off if use a small force (shaking also will do).

The problem of base and emitter terminal are not so much problem (as pad let us do easy job, but they still hard to solder than typical TO-264 or similar (which standing, not flydisk shape)
The collector (entire casing and 2 holes) surface is the most difficult, like spending most of the time doing that and FAIL !

So any guys have nice and brilliant idea or experience to share with me ? in order faster and easier to solder these TOUGH 'guy'.
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Old 26th September 2011, 03:33 PM   #2
poynton is offline poynton  United Kingdom
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You are not supposed to solder directly to the case of a TO3 transistor.

They are normally attached to a heatsink and the method of connecting the collector lead is to use a solder tag under one of the mounting bolts.

The connections to the base and emitter should not be a problem with the correct soldering iron, at least 25watt, and also use the correct solder - not silver or leadfree.


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Old 26th September 2011, 03:41 PM   #3
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Originally Posted by poynton View Post
You are not supposed to solder directly to the case of a TO3 transistor.


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Also you could destroy the transistor doing this.
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Old 26th September 2011, 03:41 PM   #4
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Default use a loop crimp connector...

Quote:
Originally Posted by guitar89 View Post
haha, i'm currently soldering some circuit and it involve a TO-3 package transistor (MJ15003).
Well.... this is the second time i try to solder such package, but both are difficult, as they are hard to wet with my solder (its my solder problem ?) They cannot 'bond' to the surface of it, which easily came off if use a small force (shaking also will do).

The problem of base and emitter terminal are not so much problem (as pad let us do easy job, but they still hard to solder than typical TO-264 or similar (which standing, not flydisk shape)
The collector (entire casing and 2 holes) surface is the most difficult, like spending most of the time doing that and FAIL !

So any guys have nice and brilliant idea or experience to share with me ? in order faster and easier to solder these TOUGH 'guy'.
check in google image.
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Old 26th September 2011, 11:46 PM   #5
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haha....... maybe it would, but i didn't solder the whole case (that would be a disaster !) just the surface around the one of the hole.
Why not leadfree ? although i use normal 60/40 standard, curious why leadfree cannot be used.

And i was attaching to the heatsink too. hm...altleast i know the correct procedure now. using solder tag seems more safe ? (I don't quite like it)
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Old 26th September 2011, 11:48 PM   #6
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Quote:
Originally Posted by guitar89 View Post


And i was attaching to the heatsink too. hm...altleast i know the correct procedure now. using solder tag seems more safe ? (I don't quite like it)
The heatsink would just suck all the heat out of your soldering iron.
The solder tags are the standard way of doing it. I was doing it in 1980 !
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Old 27th September 2011, 12:03 AM   #7
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hm...... it seems my older iron was quite powerful ? (about 60W i think) well... i will power off it when the temperature was too intense to prevent component damage during soldering.
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Old 27th September 2011, 04:34 AM   #8
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If u wish to, u can solder the round dust cap of the transistor using 60W iron, but see that the transistor is not mounted on the heatsink while soldering.

Gajanan Phadte
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Old 27th September 2011, 07:43 AM   #9
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wahaha, i prefer not, most likely to over heat the transistor.
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Old 27th September 2011, 07:51 AM   #10
poynton is offline poynton  United Kingdom
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Quote:
Originally Posted by guitar89 View Post
.........................

Why not leadfree ? although i use normal 60/40 standard, curious why leadfree cannot be used.

................
Leadfree and silver solder both melt at a higher temperature than 60/40 solder.

Leadfree also does not "wet" the surface as well as 60/40.

This leads to more bad ( dry ) joints.

For example, the problems encountered by owners of the playstation were directly down to the use of leadfree solder.


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