gary wrote:
Cross dowels (with connector bolts) are used to make strong joints
when two pieces of wood are joined at a right angle.

But I need a way to attach a bracket to the face of a particle board
so the screws don't pull out of the particle board.

I remain unconvinced that sheet metal screws will not serve the purpose.
The weight of the tray and the keyboard should present no challenge to a
properly sized set of screws. Most of the pull on those screws is going to
be perpendicular to the threads, and at that, it's going to be a very low
amount of force. I'm just not convinced that you have such a big problem
here.

--

-Mike-