Electrical safety with pcb mount transformer

diycore · 30th August 2009, 12:57 PM

Hi,

I'm designing a PCB for a PCB mount toroidal transformer. However I could not find a good amount of articles on the internet which clearly states the safety standards involving mains circuit on a PCB.

I would use standard PCB mount IEC power inlet with fuse drawer and PCB mount transformer. I would like to insulate the solder joints on the bottom side of the board.

The component leads would be bent parallel to the solder pad before being soldered. I am looking for a practical method to insulate these pads.

I would appreciate any inputs.

Patrick

DigitalJunkie · 30th August 2009, 03:55 PM

I've used fingernail polish before,it seems to work well.

Juergen Knoop · 30th August 2009, 04:09 PM

commercial equipment does not rely on coatings or lacquers for good reasons.
Insulation is provided by air/creeping distance and solid insulation materials such as plastic sheets.
Open some equipment for reference please.
regards

amc184 · 8th September 2009, 07:21 AM

The ones I know of:

- at least 10mm clearance between mains voltage and low voltage traces on the PCB.
- an insulating sheet between the underside of the PCB and the chassis, either fixed to the PCB or the chassis. This is probably only strictly necessary for a double insulated appliance though.

Shaun · 8th September 2009, 09:18 AM

I seem to remember a standard IEC 60950. There are various parts, but I think the ones that would be most helpful would parts 2 & 3.

AndrewT · 8th September 2009, 10:48 AM

I would insulate the chassis underneath the "mains" area with two layers of heavy duty adhesive tape.
I would place the "mains" area near an edge of the PCB.
I would ensure the trace layout meets the special requirements for creepage distance.
I would ensure that when the case is open, I cannot accidentally touch or drop any anything on the "mains" traces and/or soldered pads/joints.

wwenze · 9th September 2009, 09:35 AM

Paper, thicker and better quality types, fixed with tape,
Black/blue/red/yellow "electrical tape",
Hot melt glue - can be used to secure filmsy connections too, I find the glue-gun as "technician's best friend" beside blu-tack and strings.

30th August 2009, 12:57 PM	#1
diycore diyAudio Member Join Date: Dec 2007	Electrical safety with pcb mount transformer Hi, I'm designing a PCB for a PCB mount toroidal transformer. However I could not find a good amount of articles on the internet which clearly states the safety standards involving mains circuit on a PCB. I would use standard PCB mount IEC power inlet with fuse drawer and PCB mount transformer. I would like to insulate the solder joints on the bottom side of the board. The component leads would be bent parallel to the solder pad before being soldered. I am looking for a practical method to insulate these pads. I would appreciate any inputs. Patrick

8th September 2009, 09:18 AM	#5
Shaun diyAudio Member Join Date: Aug 2001 Location: Cape Town, South Africa	I seem to remember a standard IEC 60950. There are various parts, but I think the ones that would be most helpful would parts 2 & 3. __________________ Shaun Onverwacht \|\|\|\|\|\|\|\|\|\| DON'T PANIC \|\|\|\|\|\|\|\|\|\|

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30th August 2009, 03:55 PM	#2
DigitalJunkie diyAudio Member Join Date: Apr 2003 Location: Portland,Oregon Blog Entries: 4	I've used fingernail polish before,it seems to work well.

30th August 2009, 04:09 PM	#3
Juergen Knoop diyAudio Member Join Date: Jan 2007 Blog Entries: 3	commercial equipment does not rely on coatings or lacquers for good reasons. Insulation is provided by air/creeping distance and solid insulation materials such as plastic sheets. Open some equipment for reference please. regards

8th September 2009, 07:21 AM	#4
amc184 diyAudio Member Join Date: May 2007 Location: Christchurch	The ones I know of: - at least 10mm clearance between mains voltage and low voltage traces on the PCB. - an insulating sheet between the underside of the PCB and the chassis, either fixed to the PCB or the chassis. This is probably only strictly necessary for a double insulated appliance though.

8th September 2009, 10:48 AM	#6
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	I would insulate the chassis underneath the "mains" area with two layers of heavy duty adhesive tape. I would place the "mains" area near an edge of the PCB. I would ensure the trace layout meets the special requirements for creepage distance. I would ensure that when the case is open, I cannot accidentally touch or drop any anything on the "mains" traces and/or soldered pads/joints.

9th September 2009, 09:35 AM	#7
wwenze diyAudio Member Join Date: Mar 2008	Paper, thicker and better quality types, fixed with tape, Black/blue/red/yellow "electrical tape", Hot melt glue - can be used to secure filmsy connections too, I find the glue-gun as "technician's best friend" beside blu-tack and strings.