From Microvias: For Low Cost, High Density Interconnects

2.5 Solder Resist Materials and Processes

IPC-T-50b defines a solder resist (mask) as a coating material used to mask or to protect selected areas of a printed circuit board (PCB) from the action of an etchant, solder, or plating. A somewhat more useful working definition for a solder resist is as follows: a coating that masks off a printed circuit board surface and prevents those areas from accepting any solder during reflow or wave soldering processing (see Fig. 2.25).

Figure 2.25: Major features of solder resist on a PCB.

The prime function of a solder resist is to restrict the molten solder pickup or flow in those areas of the PCB, holes, pads, and conductor lines that are not covered by the solder resist. PCB designers, however, often expect more functionality out of the solder resist than just a means to restrict the solder pickup. Table 2.26 lists the functions of a solder resist.

TABLE 2.26: Functions of Solder Resists

Reduce solder bridging and electrical shorts

Reduce the volume of solder pickup to obtain cost and weight savings

Reduce solder pot contamination (copper and gold)

Protect printed circuit board (PCB) circuitry from handling damage, i.e., dirt, finger prints, etc.

Provide an environmental barrier

Fill space between conductor lines and pads with material of known dielectric characteristics

Provide an electromigration barrier for dendritic growth

Provide an insulation or dielectric barrier between electrical components and conductor lines or via interconnections when components are mounted directly on top of the conductor...

Products & Services
SMT Manufacturing Equipment
Surface mount technology (SMT) manufacturing equipment is used to populate printed circuit boards (PCB). This includes soldering machines, ovens, component placement, paste depositors and screen and stencils.
AC Power Connectors
AC power connectors transfer alternating current through a variety of electronic devices. AC power connectors include simple AC inlets, outlets, and power entry modules.
Board Mount Transformers
Board mount transformers are transformers designed to be embedded in or mounted on computer boards.
Power Connectors
Power connectors transfer AC or DC through a variety of electronic devices and are used in a variety of commercial, industrial, and residential applications. Power connectors range from simple AC or DC inlets and outlets to sophisticated power entry modules
Resistor, Capacitor Networks
Resistor, capacitor networks (RC networks) are integrated circuits (ICs) that contain resistor-capacitor arrays in a single chip.

Topics of Interest

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To achieve the best performance from M/A-COM's LSM1 VCO series, it is critical that good design practices are used in the layout of the printed circuit board. This application note describes the pad...

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Surface-mount technology has become synonymous with the use of solder paste. Paste was developed to provide a high throughput and yields to increasingly complex printed circuit board (PCB) assemblies.

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