What you should be more worried about is the placing of said brand names in your story. If you have like, a Coca-Cola vending machine reference or something, cool. But if you're forcing the brand names into dialogue or just putting it where it doesn't make sense, it can make your story/comic come across as cheap and unnecessary. Plus, depending on the brand, it could potentially age your comic horribly down the road (but most big brand names have been around for decades and they're probably not gonna go down any time soon, at least not within the lifespan of a comic...)
But as long as you don't dump brands all over your comic (unless it's a comic that jokes about brand names or something) and practice what people have said above (if you're not making millions off your comic or the brand names mentioned in the comic, company's not gonna bat an eye) you'll be fine 