Wire-To-Board (WTB)

Overview

Wire-to-board (WTB) connectors are a very common type of electrical connector. WTB connectors are used to attach free wires and cables to a PCB, to provide both electrical connections and mechanical support.

Naming

The name can be abbreviated to WTB connectors or W-T-B connectors. They can also be referred to as board-to-wire connectors.

WTB connectors get rid of all the problems with soldering wires directly onto a PCB, which include fatigue/breaking issues, short-circuit woes, and the ease of disconnecting/re-connecting the wires.

Trying the find a good, reasonably-priced WTB connector on a electronic supplier’s website can be near-impossible. There are so many varieties, shapes, lead pitches, bad datasheets, and different manufacturer’s making nearly identical products. Also, to top it all of, you need to usually find more than one item to make a connector work (e.g. if you buy a connector you must also find the matching receptacle and crimp pins). And most suppliers don’t do a good job and making the related parts obvious.

Examples

TE Connectivity HPI

TE Connectivity’s 2.0mm HPI connectors are a good choice if you want a smallish connector with 2 to 12 wires. There are SMD and TH variants of the PCB mounted half. I like these because they are relatively cheap, have good documentation, and best of all, come with 3D step models for creating a 3D mock-up of the PCB.

Manufacturing codes include 1775469-x for the right-angle SMD variants, and 1775470-x for the vertical SMD variants. x is the number of pins in all cases.

Molex PicoBlade

Molex’s PicoBlade connector families are quite popular. They have a 1.25mm pitch and a 1A capacity per contact. There are a variety of wire-to-board and wire-to-wire options.

A photo showing a few of the connectors from the Molex PicoBlade families. Image from www.molex.com.
A photo showing a few of the connectors from the Molex PicoBlade families. Image from www.molex.com.

MTA/CST-100 Connectors

MTA-100 connectors are colour coded according the wire size they accept.

Connector Colour Wire Size
Red 22AWG
White 24AWG
Blue 26AWG
Green 28AWG