Abstract: A sheet cleaning apparatus having sets of cleaning rollers, wherein the rollers are integrated into a removable cartridge structure. Couplers are provided at roller shaft ends to connect to the roller drive. The cartridge is received in a slide carriage, permitting the cartridge to be readily removed from the apparatus by sliding the carriage out, and lifting the cartridge out from the slide carriage. With this arrangement, the down time for the sheet cleaning apparatus is minimized, since the sheet cleaning apparatus can be provided with two cartridges, and the cartridge needing maintenance can simply be quickly removed and replaced with a fresh cartridge. The production line can quickly be put back into operation, and the removed cartridge can be serviced off line for subsequent use.

Abstract: A sheet cleaning apparatus having sets of cleaning rollers, wherein the rollers are integrated into a removable cartridge structure. Couplers are provided at roller shaft ends to connect to the roller drive. The cartridge is received in a slide carriage, permitting the cartridge to be readily removed from the apparatus by sliding the carriage out, and lifting the cartridge out from the slide carriage. With this arrangement, the down time for the sheet cleaning apparatus is minimized, since the sheet cleaning apparatus can be provided with two cartridges, and the cartridge needing maintenance can simply be quickly removed and replaced with a fresh cartridge. The production line can quickly be put back into operation, and the removed cartridge can be serviced off line for subsequent use.

Abstract: An overlay sheet having a first thin layer of a polymer material, a second thin layer of a hard material such as a phenolic, melamine or metal foil, and a third thin layer of a polymer material, the first and third layers sandwiching the second layer. The sheet is applied to a surface of a printed circuit board such that the third layer is against the board surface, and the first layer is exposed to receive the drill bit. During drilling operations, the drill bit is advanced initially through the softer first layer of the polymer material, immobilizing the tip of the drill bit against lateral movement, then through the harder layer, then through the softer third layer, and finally through the printed circuit board. The harder layer prevents formation of burrs, and the polymer material inhibits drill bit wander.

Abstract: A sheet cleaning apparatus having sets of cleaning rollers, wherein the rollers are integrated into a removable cartridge structure. Couplers are provided at roller shaft ends to connect to the roller drive. The cartridge is received in a slide carriage, permitting the cartridge to be readily removed from the apparatus by sliding the carriage out, and lifting the cartridge out from the slide carriage. With this arrangement, the down time for the sheet cleaning apparatus is minimized, since the sheet cleaning apparatus can be provided with two cartridges, and the cartridge needing maintenance can simply be quickly removed and replaced with a fresh cartridge. The production line can quickly be put back into operation, and the removed cartridge can be serviced off line for subsequent use.

Abstract: An overlay sheet having a first thin layer of a polymer material joined to a second thin layer of a hard material such as a phenolic, melamine or metal foil. The sheet is applied to a surface of a printed circuit board such that the metal foil is against the board surface, and the first layer is exposed to receive the drill bit. During drilling operations, the drill bit is advanced initially through the softer first layer of the polymer material, immobilizing the tip of the drill bit against lateral movement, then through the harder layer, and finally through the printed circuit board. The harder layer prevents formation of burrs, and the polymer material inhibits drill bit wander.

Abstract: Apparatus for cleaning foreign particles from the surface of sheets of material, such as printed circuit boards during fabrication processing. Two pairs of sheet cleaning rollers are located along the sheet path, and the sheet is passed through the nips between the pairs of rollers. The rollers have a surface tack sufficient to transfer the foreign particles from the surfaces of the sheet to the cleaning roller surfaces. Upper and lower roller cleaning rolls having surfaces of even greater surface tack are arranged in tangential contact with respective ones of the sheet cleaning rollers. The surfaces of the roller cleaning rolls have even greater surface tack, sufficient to transfer the foreign particles from the sheet cleaning rollers to the cleaning roll surfaces. An adjustable preload force is applied to each roller cleaning roll to urge each roll against the sheet cleaning roller surfaces.

Abstract: A method for drilling very small diameter holes (0.005 inches or smaller) in a printed circuit board is described, employing an entry overlay sheet. The entry overlay sheet is a thin layer of a homogenous polymer material, having a thickness of 0.005 to 0.010 inches, but at least 1.5 times the drill diameter. To provide improved drilling characteristics the polymer may be filled with mineral filler particles such as talcum powder. The method of drilling the printed circuit board includes (i) placing a sheet of this entry material on top of the printed circuit board, and (ii) drilling through the entry material and printed circuit board in succession.