blown coil pack

Hello I have a 91 buick park ave (3800), and I have replaced the coil pack at least 4 times they keep blowing out. The spark plugs has carbon on them. I am tired of replacing these coil pack what cause them to blow out like that? need more info let me know thax.

you dont say if these are new gm, aftermarket, or junk yard coil packs

What test did you use to determine they were bad? Make sure by removing the 2 wires attached to 1 segment at a time, start (or attempt to) and watch the spark jump across the open terminals. If all three segments do this, the coil pack is probably good. If good, measure resistance in your plug wires, check the coil connector, replace spark plugs, etc. Plugs and wires are cheap, install proper replacements and reduce possibilities.