[SOLVED] Burnt PCB board from burnt components , does it have carbon in the PCB?

[danny davis]

At work there is PCB boards that are BURNT because of the components got very hot and burnt to black themselves

How do you know is there is carbon in the PCB board now? my manager calls it carbon substrate

When the PCB board is BURNT , and you put new components ontop of the burnt pcb , what happens?

Is the BURNT pcb board a parallel path for current?

Is the BURNT pcb board have resistance? does it add resistance to the traces where it's burnt?

My manger used a Fiber glass eraser to erase the burnt PCB board, but it just makes a PIT in the PCB but it's still burnt

My manager said you can lay components over the BURNT PCB board because the BURNT PCB board doesn't do anything to the circuit, is this true?

The BURNT PCB board does touch other pads and traces

It's a double sided PCB board

If the BURNT PCB board didn't touch other pads or traces would this be true that it won't do anything and you can lay new components ontop of it and solder new ones in place even tho it's burnt underneath?

 

[FvM]

Not easy to answer. Most PCB (FR4 and similar) are glass/epoxy substrates. Epoxy resin is an organic compound containing carbon. It decomposites to various matter, e.g. carbon when burned. Besides missing mechanical stability, also the electrical properties of the burned PCB substrate change. There will be no massive shorts but may be excessive leakage currents. Isolation voltage strength is no longer maintained.

Generally speaking, burned PCBs are considered as total-loss by most serious repair workshops, for good reasons I think.

Small burned zones can be possibly stripped off and preferably filled/sealed with epoxy glue.

 

[chuckey]

Many years ago I did some research into this topic. Burnt PCB material suffers from tracking and moisture absorbtion. However for non tropical use and with no high voltages (>200V?) present, burnt boards once cleaned as per Managers technique, work reliablely over a long period.
This problem occurred in 1984 in PCBs in PSUs, the diodes (Motorola I think) were designed to conduct their heat away via their very thick wires , which were soldered directly into a PCB. After a couple of years the silhouette of the PCB track was visible through the PCB, because the glass fibre had been severley burnt due to overheating from the diodes dissipation. Without any corrective work the PSUs lasted until at least 2011, when their service was terminated. The PSUs were on for 24/7 so very got cold or wet.
Frank

 

[danny davis]

When a PCB board is burnt , can you put new components and solder them in?

Or is the BURNT PCB going to cause resistance in the circuit? leakage in the circuit? a partial short?

What is bad about a PCB board that is burnt? it does what to the circuit?

The Burnt PCB board carbon does what to the circuit?

 

[Audioguru]

Why was this SAME THREAD closed on the other website forum by the Super Moderator but it is still open here??

 

[danny davis]

I guess u don't know the answers to these questions

When a PCB board is burnt , can you put new components and solder them in?

Or is the BURNT PCB going to cause resistance in the circuit? leakage in the circuit? a partial short?

What is bad about a PCB board that is burnt? it does what to the circuit?

The Burnt PCB board carbon does what to the circuit?

 

[FvM]

Why was this SAME THREAD closed on the other website forum by the Super Moderator but it is still open here??

I guess u don't know the answers to these questions

I'm confident, Edaboard members are well able of ignoring a thread on their own when a poster repeats questions without reading answers.

 

[danny davis]

can u please help me out with the questions , I need to know about this please

When a PCB board is burnt , can you put new components and solder them in?

Or is the BURNT PCB going to cause resistance in the circuit? leakage in the circuit? a partial short?

What is bad about a PCB board that is burnt? it does what to the circuit?

The Burnt PCB board carbon does what to the circuit?

 

[FvM]

I'm under the impression that chuckey and I answered the question."Burnt" is a rather vague description. Can mean everything from a slightly brown board surface up to carbonized holes.

 

[danny davis]

If you have carbonized hole or a carbonized burnt pit , can this cause voltage and current leakage? what problems can it do to the circuit?

 

[Audioguru]

It is unprofessional to call a burnt pcb "repaired".
I would be ashamed to give it to anybody.
It should be trashed.

 

[danny davis]

What is wrong with laying new components ontop of a burnt PCB board? what can go wrong with the circuit? does the carbon cause leakage? or add resistance to the circuit?

 

[danny davis]

Here is the pictures of the burnt PCB, can I put new component on this board and will it work ? or what can the problems cause

 

[Audioguru]

Here is the pictures of the burnt PCB, can I put new component on this board and will it work ? or what can the problems cause

Here is the pictures?? No. In English we say, "Here ARE the pictures".
You didn't post for a while so I was hoping you were gone or were banned again.

Aren't you ashamed of yourself to call that destroyed circuit board a board repaired by you? I would never allow a destroyed board like that to go back into operation.

 

[bigdogguru]

I'm confident, Edaboard members are well able of ignoring a thread on their own when a poster repeats questions without reading answers.

Honestly, I'm not so confident.

Time to take a deep breath everyone and calm down.

Thread Closed.

BigDog