Plated Through Hole
Synonyms: PTH, Thru Hole, Through Hole
Plated Through Hole Definition
Plated Through Holes are PCB features that are either milled or drilled, and then plated afterwards with conductive copper. By running traces between the plated through holes, components soldered in those positions are then electrically connected to other components on the circuit board. A well designed plated through hole will have an annular ring of conductive copper surrounding the outside diameter of the hole, usually some percentage larger than the hole itself. This provides a mechanically sound location where solder can be applied to secure a component to that hole. On boards with multiple inner copper layers, connections can be made internally in the PCB between the plated through hole and traces run on those inner layers.
The act of drilling holes of any sort in a PCB requires the use of drill bits and endmills in small diameters, made from tungsten-carbide. Carbide is used because the substrate, typically FR-4, is extremely abrasive causing rapid wear and dulling of the cutting tool. As a result, the more holes there are in a PCB, the more expensive it will be to manufacture.
Plated Through Hole Examples
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- Two Layer PTH
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- Four Layer PTH
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- PCB Drill Bits
Further Reading
