The high-temperature kraft base behind clean exit and low burr on paper-backed (phenolic) PCB backup boards — and the packing paper used in lamination press cycles.
PCB kraft paper is a dense, high-purity kraft fibre sheet. In drilling it is the base material of phenolic backup boards (PHE grade): the kraft is saturated with phenolic resin and cured into a rigid, flat sheet that supports the drill bit on exit, controls burr and protects the drill on breakout. In lamination it is used as press packing paper between stacked booklets.
| Base fibre | High-density kraft paper |
|---|---|
| Impregnation | Phenolic resin (cured) |
| Heat resistance | Rated for sustained drilling spindle heat |
| Typical thickness | 0.5 – 2.5 mm (as backup board) |
| Exit burr (PHE board) | ≤ 0.05 mm below Ø0.10 mm holes |
| Compliance | ROHS / E1 |
Kraft paper is the raw base fibre; a phenolic backup board is that kraft paper saturated and cured into a rigid drilling sheet. The resin gives the board its hardness, heat resistance and flatness. For production drilling the cured phenolic kraft board is the choice; loose kraft is used for lamination packing. Both work alongside HDF, UV melamine and wood backup boards depending on the hole size and substrate.
What is PCB kraft paper? PCB kraft paper is a high-density kraft fibre sheet used as the base material for paper-backed (phenolic) PCB backup boards. It sits under the drilling stack to support the drill on exit, control burr and protect the bit.
What is PCB kraft paper used for? It is used in PCB drilling as the cushioning base of backup boards, and in lamination as press packing paper. In drilling it reduces exit burr, improves hole-wall quality and lowers bit breakage on breakout.
Is PCB kraft paper heat resistant? Yes. Drilling-grade kraft paper is phenolic-impregnated and rated for the heat and friction of high-speed drilling. High-temperature grades stay stable through sustained spindle heat without delaminating or charring.
What is the difference between kraft paper and a phenolic backup board? Kraft paper is the raw base fibre; a phenolic backup board is that kraft paper saturated with phenolic resin and cured into a rigid, flat sheet. The resin gives the board its hardness, heat resistance and dimensional stability for drilling.
Can kraft paper be used directly as a PCB backup board? Loose kraft paper is not used directly; it is converted into a phenolic-impregnated backup board. For most HDI and multilayer drilling, the cured phenolic kraft backup board (e.g. our PHE grade) is the production choice, while raw kraft is used as lamination packing paper.