Morning Wolfgang & All -

I've had fairly good success in the past using additive bus bars which are installed on the board towards the end of the assembly process.  This helps to avoid difficulties both at the board fabrication and the assembly stages.  There are quite a number of suppliers of these devices, or most board fabricators can etch custom forms to your design, from copper sheet.

The use of extremely heavy copper is possible, but it tends to increase the probability of board warpage and also acts as a heat sink during the assembly soldering process.  If this approach is the only possibility, then I would suggest you enlist your board fabricators assistance before design completion in order to arrive at a solution both of you can live with.   There are several houses that do specialize in the heavy power boards - all seem to have their own recipes for success.

You may need to consider laminates with a higher Tg to accomodate prolonged solder cycle durations.  SMOBC on external conductors is almost essential to prevent solder globs picking up on the heavy copper areas during wave soldering.

Regards - Kelly
    -----Original Message-----
    From: Erat, Wolfgang <[log in to unmask]>
    To: [log in to unmask] <[log in to unmask]>
    Date: Wednesday, March 29, 2000 12:28 PM
    Subject: [TN] boards for high current loads
    
    
    Hello 

    I have a number of requests on my desk where customers need some areas of 
    boards with very thick copper (6 to 12 ounces for some heavy duty current) 
    and the rest of the board with standard fineline features. 

    Heavy duty plating ?? double imaging ?? etching through a bunch of copper ? 
    none are attractive options. 
    Any and all ideas on alternate processes would be appreciated. 

    Thanks, Wolfgang 

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