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A circuit board packaging technique in which the leads (pins) on discrete components and chips are inserted through holes in the printed circuit board and soldered from beneath. Until the late 1980s and prior to surface mount technology, all devices on circuit boards were thru-hole. Although chips are mostly surface mounted these days, some chips are still thru-hole, and most discrete devices such as resistors and capacitors are thru-hole.

Thru-hole devices have a strong bond with the board but require an extra drilling step. They also eliminate the board real estate underneath from being used for other layers. See surface mount.

Through the Board
In this circuit board from an LED table clock made in 2005, not only the discrete components, but the chip, are thru-hole devices.

Thru-Hole vs. Surface Mount
The thru-hole chip is not only thicker than the surface mount chip, but it eliminates the real estate underneath because the pins stick through. The board designer must route any traces from other layers around that part of the board.
References in periodicals archive ?
Features of the ER10M thru-hole RF inductor series include:
These components are known as thru-hole (sometime spelled through-hole) components, and are still popular today.
Featuring a DOSA compatible pin-out, the iAD series of 16-Amp non-isolated, single inline package (SIP), thru-hole mounted devices are only 2.
The line also offers retracting clamps, edge clamps, thru-hole hydraulic cylinders, rotary unions, collet chucks, and work supports.
Thru-hole components supplied as conformally coated axial devices.
The device mounts to an adapter board terminated with male thru-pins, creating a thru-hole solder tail socket for BGA devices.
The Hawk TC-300 CNC turning center has thru-hole bar stock capacity of 3.
The digital- features Hawk TC-300 CNC Turning Center; with large thru-hole bar stock capacity of 3.
2 mounting options: a robust magnetic mount and a center thru-hole.
The ROTA NCD lathe chuck features an extra large thru-hole and uses collet top jaws for accurate clamping of small diameter workpieces.