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TO-247 bent pins

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123mmm

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Long-short question: I am working at a new project, a lab power supply. I used some TIP3055 for this project. Those TIP3055 were recovered from another project and the pins were a little bit short. I was forced to bend them from near the plastic case to make them fit to the new project PCB. Those TIP3055 are from ON Semi.
I think that bending the pins near the plastic case is not such a good idea...
Please help me with an advice: if the project is working, it is safe to use it as it is ?
I am uploading a few photos of the pins of the transistors.
https://ibb.co/dM3ZqqM
https://ibb.co/YkcNKJD
https://ibb.co/L9cTvhj
 
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JimB

Super Moderator
Most Helpful Member
I think that bending the pins near the plastic case is not such a good idea...
Correct.
In a commercial setting with a rigorous QA inspection, it would be rejected.

if the project is working, it is safe to use it as it is ?
Yes, there should be no problems.
Use your PSU and enjoy the electronics experimentation.

Bending leads close to a component can cause cracking of the plastic body of the component, whether it is a a resistor, capacitor, transistor or IC, this will lead to moisture from the air entering the component and degrading its performance.

JimB
 

dknguyen

Well-Known Member
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Only bend if you can grasp the lead on the case side to prevent stress from being transmitted to the component. A thinner grabbing tool lets you bend closer to the component body. I don't use components that are bent without securing the case side.
 
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dr pepper

Well-Known Member
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So long as the board is supported and nothing moves it doesnt look so bad.
Although it isnt good practice.
 

dr pepper

Well-Known Member
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With 0.47 ohm resistors that look about 2 watts that thing will be loading each tip3055 around 2 amps.
They should cope with hat ok.
 

unclejed613

Well-Known Member
Most Helpful Member
one thing to be wary of is that eventually one of the leads might break off right at the bend, or at the edge of the plastic. this is because the metal pins expand and contract due to thermal cycling, and just as you can break a piece of steel bar stock by bending it back and forth even at a very slight angle), the leads break off from metal fatigue. that's the reason it wouldn't pass QA in an industrial environment, but for your own use it should be ok.
 
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