I want to build a free-standing cabinet for the kitchen but since it is my cabinet build, I am not very sure about being able to make a solid/stable cabinet without back panel. It will probably have 4 shelves (fixed) with each shelf divided into 70/30 width with alternating 70/30 divisions (1st "left" shelf is 70%, right shelf is 30% wide, second left shelf is 30% and right shelf is 70% wide and so on), so no vertical board dividing the cabinet in half.
Internet tells me the a 6 mm (quarter inch) plywood board is good enough for the back panel. Planning to make rabbet for back panel with circular saw and sanding. The problem that I am facing is that I cannot find a single plywood board big enough for the back panel. I want to ask if it is ok to use 2 plywood boards? Would it give the structural integrity that I am looking for, to avoid the cabinet from wobbling? I only have a circular saw so the boards might not join perfectly. The seam would also be visible from the front of the cabinet, which is not visually appealing. If there are any other solutions to solve the issue, please let me know.
Some details about cabinet below:
Material for box and shelves: 19 mm Chipboard (3/4 in)
Dimensions: 150 x 85 x 50 cm (H x L x W)
Shelf joining method: Cleats