12 x 12 Heavy Duty Chipboard Pad (.030 Thick) 490/CaseChipboard sheets are commonly used to provide added protection when stacking paper in boxes, or as the stiff backing seen on pads of legal or notebook paper. Our tough chipboard constructed from either . 030 Heavy Duty Kraft paperboard or Extra Heavy Duty . 050 Kraft paperboard is available as sheets or pads in different sizes and quantities according to your needs. They are also used for strengthening envelopes or mailers.