effect of electrical bias on solder cracked

[cinderella1]

That's exactly what I told him/her in chat but he/she refused to listen.

EDIT: Ha, now she's started the revenge game--I disliked her post, she disliked mine. How mature...

your post not helpful at all so it deserved a disliked

 

[DerStrom8]

your post not helpful at all so it deserved a disliked

That post was simply saying that I already answered your question in the chat, but you ignored it. Why are you ignoring the answers people are giving you?

 

[Ian Rogers]

good idea..but will it affect the solder performance?

Possibly!! But if the solder is indeed cracked, it will need re-flowing anyway..

 

[cinderella1]

Possibly!! But if the solder is indeed cracked, it will need re-flowing anyway..

thanks for the new idea. Now i understand

Cracks in solder joints show up real easy using freeze spray.

thanks for intro me this new method.. besides locating the crack, this spray also provides heat sink protection for heat sensitive components during soldering and desoldering. tq

 

[cinderella1]

i would like to know how much is the maximum temperature can be tested on diode? I am using the High Voltage Diodes (not the normal plastic diode).
my 2nd question is what is the minimum temperature muffle furnace can be set? thanks

 

[DerStrom8]

i would like to know how much is the maximum temperature can be tested on diode? I am using the High Voltage Diodes (not the normal plastic diode).
my 2nd question is what is the minimum temperature muffle furnace can be set? thanks

You're asking very broad questions now, there's no way to answer them with such vague information. Be more specific--what exact diodes are you using (part numbers are a must!). What furnace are you using (brand/model name, age, etc)?

You can't expect people to answer your questions if you don't give enough information to go on.

 

[Ian Rogers]

Each component has a "recommended" temperature to keep within... But the solder will melt before you get to this temperature.... Rule of thumb is to keep excessive heat (ie.. soldering irons) to within 10 seconds on a component... These are normally @ 350 degrees. I doubt anyone will know how much heat will destroy the component...

 

[KeepItSimpleStupid]

There should be a Tj(max) or Max Junction temperature, Guaranteed, you can't exceed that one. Remember, that some contribution will be from testing as well.

 

[JimB]

Can I ask, what is the point of this discussion?

Are you trying to find how many heat cycles are required to break a solder joint?
Or how many mechanical stress cycles to break the joint?
Or trying to find a test to determine if the joint is broken?

The discussion just seems to go around in circles.
What are you trying to do?

JimB

 

[Ian Rogers]

JimB I have also asked that same question... I am trying to help the OP relay the question so we can understand better..

 

[alec_t]

According to the Hitchhiker's Guide to the Galaxy the answer is 42 .

 

[cinderella1]

According to the Hitchhiker's Guide to the Galaxy the answer is 42 .

comic science fiction series? what is 42 for?

 

[cinderella1]

Can I ask, what is the point of this discussion?

Are you trying to find how many heat cycles are required to break a solder joint?
Or how many mechanical stress cycles to break the joint?
Or trying to find a test to determine if the joint is broken?

The discussion just seems to go around in circles.
What are you trying to do?

JimB

im trying to find out heat cycles are required to break a solder joint. but at the same time i need to make sure the component that im using is suitable and can adapt to that heat. i juz want sure the solder can be cracked without affecting the component im using such as the diode and PCB. thanks for understanding

 

[alec_t]

comic science fiction series?

Yes. Based on a book by Douglas Adams.

what is 42 for?

'42', according to the computer featured in the book/series, is 'the answer to Life, the Universe, and everything.'

i juz want sure the solder can be cracked without affecting the component im using such as the diode and PCB.

I doubt you could ever be sure of that. Much would depend on the particular diode, pcb and heat treatment.

 

[JimB]

im trying to find out heat cycles are required to break a solder joint. but at the same time i need to make sure the component that im using is suitable and can adapt to that heat. i juz want sure the solder can be cracked without affecting the component im using such as the diode and PCB. thanks for understanding

From 50 or so years of experience with various types of electronics, most broken solder joints on a PCB are caused when the component held by the solder joint is either very hot or heavy, or sometimes both.

The usual components to suffer from this problem are:
Large resistors, usually wire wound.
Power semiconductors, large diodes or transistors which are also mounted on a heatsink.
Transformers which are held on the PCB by the connecting leads.

As well as simple heating effect considerations, I think that physical expansion and contraction plays a big part in the problem.
When the component gets hot it expands, only a small amount. But if there is no flexibility in the mounting or connection leads, there will be physical stresses on the solder joints.
After several years the joint may fail.

Whenever I have come across this effect, most of the time the repair just involved sucking out the old solder and re-making the joint with new solder. The component and the PCB suffer no damage.

However...
Where the design was poor, the resistor was running VERY hot and the thermal conduction path from the component to the joint was short, leading to overheating and discolouration of the circuit board material, the circuit tracks at the solder pad on the board can lift from the board.
This should not happen in a correctly designed circuit board.

JimB

 

[cinderella1]

Yes. Based on a book by Douglas Adams.
'42', according to the computer featured in the book/series, is 'the answer to Life, the Universe, and everything.'
I doubt you could ever be sure of that. Much would depend on the particular diode, pcb and heat treatment.

ya..its all depends on the component used. juz wonder how much is the temperature range for muffle furnace.

 

[alec_t]

how much is the temperature range for muffle furnace.

Check its spec, or ask the manufacturer.

 

[cinderella1]

From 50 or so years of experience with various types of electronics, most broken solder joints on a PCB are caused when the component held by the solder joint is either very hot or heavy, or sometimes both.

The usual components to suffer from this problem are:
Large resistors, usually wire wound.
Power semiconductors, large diodes or transistors which are also mounted on a heatsink.
Transformers which are held on the PCB by the connecting leads.

As well as simple heating effect considerations, I think that physical expansion and contraction plays a big part in the problem.
When the component gets hot it expands, only a small amount. But if there is no flexibility in the mounting or connection leads, there will be physical stresses on the solder joints.
After several years the joint may fail.

Whenever I have come across this effect, most of the time the repair just involved sucking out the old solder and re-making the joint with new solder. The component and the PCB suffer no damage.

However...
Where the design was poor, the resistor was running VERY hot and the thermal conduction path from the component to the joint was short, leading to overheating and discolouration of the circuit board material, the circuit tracks at the solder pad on the board can lift from the board.
This should not happen in a correctly designed circuit board.

JimB

Thanks JimB for sharing that knowledge. "sucking out the old solder and re-making the joint with new solder" thats interesting information. maybe i can add that into my report. BTW, do you know anything about muffle furnace? i have only this option to crack the solder. im planning to use air chamber but it is not available in my place. i really have less information about this furnace(only know it can goes up to 1500degree celcius)

 

[cinderella1]

Check its spec, or ask the manufacturer.

just saw this one **broken link removed** (min is 900C)

 

[JimB]

how much is the temperature range for muffle furnace

I just did a quick "google" and found references for muffle furnaces going up to 1800 degC.
This may be a little bit higher than the average circuit board can tolerate.

JimB