I have trouble with forearms also. I believe that heavy ass back work, deads and static holds work the best. Wrist curls tear the hell out of my tendons.
Preform wrist curls while holding the bar behind your back, palms facing away from you. Since I started doing that I find them much more comfortable and effective.
They seem to add a bit of mass to mine, but I'm sure you can get the same effect with heavy compound lifts. You're not going to bench, clean, deadlift and squat and grow on your chest, back, shoulders and triceps immensely while having your forearms stay the same. Nuh-uh. Doesn't happen.
Have added some size to my forearms by doing 2 exercises for front and 2 for back o the arm. BB wrist curl behind back, followed up with palm facing forward BB curls. 2 min break followed with palms up DB wrist curls then palms down DB Wrist Curls.
Have gone from Deading 150 to 225 easy because I can now hold the weight.
I've been doing intense 6x20 cycles of wrist curls and reverse wrist curls. I also recently added abduction (up and down - kind of a jerkoff movement).
A few days ago I changed to 5x10 with heavier weights.
There HAS been pretty good growth, but it's all in the top half of my forarm and not the bottom half where my wrists are. My wrists look sadely skinny as do my forarms right near them.
I think the changes to my routine will work well (dropping the reps, boosting the weight). My forarms were totally pumped and I could really feel the burn.
I'll probably go ahead and get the grippers, though, and start building the grip strength.