STENCIL FOR HOLE DRILLING Russian patent published in 2014 - IPC B26F1/16 H05K3/00 B23B35/00 

FIELD: machine building.

SUBSTANCE: stencil comprises a layer of crystallised water-soluble polymer composition from 0.02 to 0.3 mm thick which is applied onto at least one surface of backing up metal foil. Average size of the crystal grain of the water-soluble polymer composition amounts to 5-70 mcm, and standard grain size deviation does not exceed 25 mcm. Surface roughness Sm in the point of drill bit tip entering the water-soluble polymer composition layer amounts to maximum 8 mcm. The layer is formed by applying of hot melt of the water-soluble polymer composition directly onto the backing up metal foil or by applying of solution containing the water-soluble polymer composition with the following drying and further cooling under the temperature reducing from (120-160)°C to (25-40)°C during 60 sec at cooling rate of at least 1.5°C/sec.

EFFECT: prevention of polymer sticking to the drill bit tip and damage of the latter.

6 cl, 6 dwg, 5 tbl