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Triac track width and clearance advices?

autodeskguest

Hi,

 

I�m making the layout for a PCB that uses a triac in TO-220 package. The maximum current in the triac (BTA312Y) is 8 Amp. and the copper thickness 35�m (1 oz/ft2). What track width would you recommend? I�ve seen calculators on the Internet but they ask the allowable temperature rise and I don�t know what value I can choose. On the other hand, I�ve seen that IPC recommends 220mil for 8 Amp., 10�C rise and 1oz/ft2 Cu but it�s very big?

 

What value do you use for track clearance for 220V mains voltages?  I�ve seen 0.75mm (http://www.electronics-project-design.com/PCB-Design.html ) for coated board. But here (http://www.smpspowersupply.com/ipc2221pcbclearance.html ) the values are not the same and I don�t know what to use? Is bare board for PCB without parts on it? So do I have to use assembly and �external components leads, uncoated� if : the board has a solder resist mask, is populated and if there is no coating on component leads?

Is the clearance also needed between the component�s pads (external diameter to external diameter)? If so, is it possible with a standard TO-220 package?

 

 

Thank you.

 

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  • Thank you for your answers.

    @jrafetseder

    It's a special manufacturing process, it's not a standard technology. For just some board it would cost a lot.

     

    I have tried to bend the triac leads (like some TO-92) in order to respect the 1.5mm clearance, but I think the leads are too small to go trough the PCB. The clearance should be 1.50mm from 301 to 500 AC peak and 0.75mm from 251 to 300 AC peak, so if I have a little less than 1.5mm I suppose it's not a big problem... The TO220 package doesn't seem to be well designed to respect the IPC clearance. 

     

     

    Can I use a track of 2.54mm wide (small length) to connect to a wider track or polygon?

     

    Thank you.

    --

    Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

     

Reply

  • Thank you for your answers.

    @jrafetseder

    It's a special manufacturing process, it's not a standard technology. For just some board it would cost a lot.

     

    I have tried to bend the triac leads (like some TO-92) in order to respect the 1.5mm clearance, but I think the leads are too small to go trough the PCB. The clearance should be 1.50mm from 301 to 500 AC peak and 0.75mm from 251 to 300 AC peak, so if I have a little less than 1.5mm I suppose it's not a big problem... The TO220 package doesn't seem to be well designed to respect the IPC clearance. 

     

     

    Can I use a track of 2.54mm wide (small length) to connect to a wider track or polygon?

     

    Thank you.

    --

    Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

     

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