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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 ?
Stackpole's RNV series of thru-hole resistors offers outstanding high voltage surge handling; up to 7 KV for 50 surges per IEC 60065.
IXYS offers a full range of discrete standard thru-hole and surface mount packages for these new Polar HiPerFET(TM) additions.
Kitagawa's PUB Series three-jaw, pull back-style power chucks with thru-hole provide the accuracy necessary for finishing applications and the ability to swallow parts.
This allows the CHAD IQ systems to handle just about any odd form thru-hole part in an application.
These configurations are available solder cup, thru-hole and pre-wired up to 26 gauge wiring.
The high-precision Spinner TS series turning center has chuck sizes from 165 mm to 250 mm, spindle thru-hole of 46 mm to 77 mm and VDI30 or VDI40 toolholders.
The right angle and vertical headers are available in thru-hole and surface mount (SMT) printed circuit board (PCB) termination styles and include thru-board, free hanging, and dual row configurations.
Working with Omnetics design team, we recommend using surface-mount nano-connectors as the main interface to the printed circuit boards to maximize signal launch from the boards to the interconnections as opposed to thru-hole.
Also shown will be Schunk's large Bore Power chucks that are designed specifically to meet the requirements of the oil field with thru-hole bores to 560 mm (22").
This product enhancement exemplifies AVX's continued support of thru-hole technology to the military and aerospace market.