A Hand Drill Machine Is A Tool Fitted With A Cutting Tool Attachment Or Driving Tool Attachment, Usually A Drill Bit Or Driver Bit, Used For Drilling Holes In Various Materials Or Fastening Various Materials Together With The Use Of Fasteners. The Attachment Is Gripped By A Chuck At One End Of The Drill And Rotated While Pressed Against The Target Material. The Tip, And Sometimes Edges, Of The Cutting Tool Does The Work Of Cutting Into The Target Material.
holes Through A Pcb Are Typically Drilled With Small-diameter Drill Bits Made Of Solid Coated Tungsten Cribide. Coated Tungsten Carbide Is Recommended Since Many Board Materials Are Very Abrasive And Drilling Must Be High Rpm And High Feed To Be Cost Effective. Drill Bits Must Also Remain Sharp So As Not To Mar Or Tear The Traces.
when Very Small Vias Are Required, Drilling With Mechanical Bits Is Costly Because Of High Rates Of Wear And Breakage. In This Case, The Vias May Be Evaporated By Laser. Laser-drilled Vias Typically Have An Inferior Surface Finish Inside The Hole. These Holes Are Called Micro Vias.
it Is Also Possible With Controlled-depth Drilling, Laser Drilling, Or By Pre-drilling The Individual Sheets Of The Pcb Before Lamination, To Produce Holes That Connect Only Some Of The Copper Layers, Rather Than Passing Through The Entire Board. These Holes Are Called Blind Vias When They Connect An Internal Copper Layer To An Outer Layer, Or Buried Vias When They Connect Two Or More Internal Copper Layers And No Outer Layers.
