PCB Assemblies 297

3D printing

The process of producing a 3D object using a specialized tool that creates successive layers of material. 3D printing must technically involve the use of a print head or nozzle, but the term is often used interchangeably with additive manufacturing (AM).

ball grid array

An integrated circuit with pins on the bottom that are soldered to the surface of a PCB with tiny balls of solder. Ball grid arrays must be soldered by a robot.

blind vias

A copper-lined hole that begins on one surface of a high-density interconnect PCB and terminates on an internal layer. Blind vias allow surface-mounted technology to connect to other layers of the PCBA.

bottom only

A lead type that is located on the underside of a component. Bottom-only leads allow components to be placed flat against a PCB, separated only by the solder.

buried vias

A copper-lined hole that begins and ends on internal layers of a high-density interconnect PCB. Buried vias connect traces on internal layers of a PCB.

capacitors

A device used to store an electric charge. A capacitor consists of one or more pairs of conductors separated by an insulator.

circuit

A completely enclosed path through which an electrical current flows. Circuits normally include a source, path, load, and control.

copper

A ductile reddish metal that is thermally and electrically conductive. Copper is used to make traces in printed circuit boards.

current

The flow of electricity through a circuit. Current is measured in amperes (A) or amps.

diodes

A two-terminal semiconductor device that allows current to flow through it in only one direction. A diode has a low resistance in one direction and a high resistance in the other direction.

double in-line package

DIP. An integrated circuit with two rows of pins that are inserted into the vias of a printed circuit board. Double in-line packages, also known as dual in-line packages, are well-suited for automated PCBA assembly.

dual in-line package

DIP. An integrated circuit with two rows of pins that are inserted into the vias of a printed circuit board. Dual in-line packages, also known as double in-line packages, are well-suited for automated PCBA assembly.

electrostatic discharge

ESD. The release of static electricity. Electrostatic discharge can damage electronic components.

electrostatic dissipative floormats

A mat made of a material that conducts electricity away from a person or object and into the ground. Electrostatic dissipative floormats can prevent static electricity from damaging electronic components.

electrostatic dissipative heel straps

A removable strap that is attached to a shoe around the ankle and under the heel that conducts electricity away from the wearer and into the ground. Electrostatic dissipative heel straps can prevent static electricity from damaging electronic components.

electrostatic dissipative shoes

A type of footwear that conducts electricity away from the wearer and into the ground. Electrostatic dissipative shoes can prevent static electricity from damaging electronic components.

electrostatic dissipative wrist straps

A type of wrist strap that conducts electricity away from the wearer and into the ground. Electrostatic dissipative wrist straps have a grounding cable that attaches to a grounded workstation.

epoxy resin

A tough, heat-resistant, dielectric resin used in advanced composites. Epoxy resin is used to make packages for integrated circuits.

fiberglass

A material composed of glass fibers suspended in a plastic matrix. Fiberglass is used as the substrate material in PCBs.

fully clinched

A through-hole terminated PCBA lead that is bent at a 90-degree angle. Fully clinched leads attach more securely to the PCB than other through-hole terminated leads.

ground

To use a wire to connect a conductive object to the ground. Grounding carries electrical charges away from objects to prevent the buildup of static electricity.

gull wing

A lead type that extends outward from the component like the outstretched wing of a seagull. Gull wing leads form foot-like surfaces to be soldered to the PCB surface.

high-density interconnect

HDI. A multi-layer printed circuit board with vertical and horizontal vias that connect the layers in a complex network of traces. High-density interconnect PCBs are more efficient, less expensive, and much smaller than other circuit boards with the same functions.

inductors

A coil of conducting wire that creates a magnetic field when current passes through it. Inductors are used to energize devices.

integrated circuits

ICs. A very small electronic circuit that contains transistors, resistors, diodes, microprocessors, and capacitors on a single chip. Integrated circuits, also known as microchips, are used in an array of electronics and can be smaller than visible to the human eye.

inward-formed L

A lead type shaped like the letter 'L.' Inward-formed L leads extend outwards from the component, then turn back sharply underneath it.

ionized air gun

A device that removes static electricity from the air by releasing electrically neutral ions and safely removes dust from electronic components. Ionized air guns are handheld and can be directed to precise parts of a PCBA.

J-type

A lead type shaped like the letter 'J.' J-type leads extend outwards from the component, then curl back underneath it.

microchips

A very small electronic circuit that contains transistors, resistors, diodes, microprocessors, and capacitors on a single chip. Microchips, also known as integrated circuits, are used in an array of electronics and can be smaller than visible to the human eye.

microvias

A via that travels between the layers of a high-density interconnect PCB. Microvias include blind vias and buried vias.

on-board termination

Ending a lead on the surface of a PCB. On-board termination involves soldering components directly to the PCB surface.

package

A protective cover designed to contain or support a semiconductor device such as an integrated circuit. Packages are made out of ceramic or epoxy resin and have pins extending from them.

pads

The copper platforms on printed circuit boards to which components are attached. Pads are surrounded by solder mask so that solder only sticks to the pads.

PCB

Printed circuit board. A layered construction of conductive and nonconductive material used to mechanically support and electrically connect electronic components. PCBs are the foundation on which printed circuit board assemblies are built.

PCBAs

Printed circuit board assemblies. A layered construction of conductive and nonconductive material with various electronic components soldered to it. PCBAs can be found in almost all electronic devices.

pick-and-place robots

A robot or robotic device that moves parts from one location to another. Pick-and-place robots, sometimes called part-transfer robots, improve the precision, quality, and speed of manufacturing operations.

pins

Conductors that provide an easy path for electricity to flow. The shape and number of pins varies for different electronic components.

printed circuit board

PCB. A layered construction of conductive and nonconductive material used to mechanically support and electrically connect electronic components. Printed circuit boards are the foundation on which printed circuit board assemblies are built.

printed circuit board assemblies

PCBAs. A layered construction of conductive and nonconductive material with various electronic components soldered to it. Printed circuit board assemblies can be found in almost all electronic devices.

quad flat package

QFP. An integrated circuit that is extremely thin and has pins extending from all four sides. Quad flat packages are mounted to the surface of a printed circuit board.

rectangular end

A rectangular metal cap on the end of a surface mounted device. Rectangular end leads are soldered directly onto the surface of a PCB.

resistors

An electronic component that regulates, limits, or opposes the flow of electrical current. Resistors tend to convert electrical energy into heat.

semi-clinched

A through-hole terminated PCBA lead that is partially bent. Semi-clinched leads attach more securely to PCBs than leads that are not clinched.

silicon

A lustrous gray, semi-metallic material. Silicon is a semiconductor that is used to make the substrate of integrated circuits.

small outline package

SOP. An integrated circuit with two rows of pins that are soldered to the surface of a printed circuit board. Small outline packages have a similar shape to dual in-line packages but are smaller.

solder

A metal or alloy with a low melting point that is melted to join materials. Solders are filler metals that are specific to soldering.

solder bridging

The formation of an unwanted connection between two or more soldered areas in a PCBA. Solder bridging can cause electricity to unintentionally travel between components.

solder mask

A layer of insulating material that prevents unwanted solder from sticking to a printed circuit board. Solder masks give printed circuit boards their green color.

soldered

A joining process in which a filler metal is melted at low temperatures to form a joint between two base metals. Soldering is often used to assemble or repair electronics.

soldering irons

A tool used to transfer heat to a metal surface in order to melt solder and form a joint or circuit. Most soldering irons resemble a large pen.

square end

A square metal cap on the end of a surface mounted device. Square end leads are soldered directly onto the surface of a PCB.

static electricity

An electrical charge caused by the buildup of friction in a person or object. Static electricity can be controlled by machine grounding or using safety accessories such as antistatic mats and electrostatic dissipative footwear.

substrate

The part of a printed circuit board (PCB) on which the copper is directly applied. PCB substrate is made of fiberglass.

surface-mount technology

SMT. A type of printed circuit board assembly with components that attach to the surface of the board. Surface-mount technology uses very small copper pathways known as microvias to attach to the PCBA.

termination

The method by which a lead on a PCBA component ends. Termination methods include through-hole termination, as well as many types of surface-mount termination.

through hole technology

THT. A method of attaching components to a PCB by inserting leads through holes in the PCB and then clipping or bending their ends. With through-hole technology, the ends of the leads are soldered to the underside of the PCB.

through hole termination

Ending a lead that passes through a hole in a PCB on the underside of the PCB. Through hole termination may involve clipping or bending the end of the lead.

through holes

A hole that passes through the entire thickness of a workpiece. Through holes have no bottom because they pass through both sides of a workpiece.

through vias

A copper-line hole that passes through a printed circuit board vertically from the top surface to the bottom surface. Through vias allow components to be inserted through the PCB and soldered to its back surface.

traces

A conductive copper path on the top of a printed circuit board. Traces are embedded in the surface of a PCB and connect electronic components in a circuit.

transistors

An electrical device that amplifies electrical signals or switches current on and off. Transistors have three or more leads.

vertical interconnect access path

Via. A copper-lined hole that runs vertically through a printed circuit board or between layers of a high-density interconnect PCB. Vertical interconnect access paths conduct electricity through PCB layers.

wave soldering

An automated joining process in which a conveyor belt loaded with PCBs passes over a vat of molten solder. Wave soldering works through convection heat transfer and capillary action.