Perfboard

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Top of a copper clad Perfboard with solder pads for each hole. CopperCladPerfboard 1.png
Top of a copper clad Perfboard with solder pads for each hole.

Perfboard is a material for prototyping electronic circuits (also called DOT PCB). It is a thin, rigid sheet with holes pre-drilled at standard intervals across a grid, usually a square grid of 0.1 inches (2.54 mm) spacing. These holes are ringed by round or square copper pads, though bare boards are also available. Inexpensive perfboard may have pads on only one side of the board, while better quality perfboard can have pads on both sides (plate-through holes). Since each pad is electrically isolated, the builder makes all connections with either wire wrap or miniature point to point wiring techniques. Discrete components are soldered to the prototype board such as resistors, capacitors, and integrated circuits. The substrate is typically made of paper laminated with phenolic resin (such as FR-2) or a fiberglass-reinforced epoxy laminate (FR-4).

A via or VIA is an electrical connection between layers in a physical electronic circuit that goes through the plane of one or more adjacent layers. To ensure via robustness, IPC sponsored a round-robin exercise that developed a time to failure calculator.

Wire wrap

Wire wrap was invented to wire telephone crossbar switches, and later adapted to construct electronic circuit boards. Electronic components mounted on an insulating board are interconnected by lengths of insulated wire run between their terminals, with the connections made by wrapping several turns of uninsulated sections of the wire around a component lead or a socket pin.

Resistor Passive electrical component providing electrical resistance

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. High-power resistors that can dissipate many watts of electrical power as heat, may be used as part of motor controls, in power distribution systems, or as test loads for generators. Fixed resistors have resistances that only change slightly with temperature, time or operating voltage. Variable resistors can be used to adjust circuit elements, or as sensing devices for heat, light, humidity, force, or chemical activity.

The 0.1 inches (2.54 mm) grid system accommodates integrated circuits in DIP packages and many other types of through-hole components. Perfboard is not designed for prototyping surface mount devices.

Through-hole technology mounting scheme used for electronic components that involves the use of leads on the components that are inserted into holes drilled in printed circuit boards and soldered to pads on the opposite side manually or by automated insertion mount machines

Through-hole technology, refers to the mounting scheme used for electronic components that involves the use of leads on the components that are inserted into holes drilled in printed circuit boards (PCB) and soldered to pads on the opposite side either by manual assembly or by the use of automated insertion mount machines.

Before building a circuit on perfboard, the locations of the components and connections are typically planned in detail on paper or with software tools. Small scale prototypes, however, are often built ad hoc, using an oversized perfboard.

Electronic design automation (EDA), also referred to as electronic computer-aided design (ECAD), is a category of software tools for designing electronic systems such as integrated circuits and printed circuit boards. The tools work together in a design flow that chip designers use to design and analyze entire semiconductor chips. Since a modern semiconductor chip can have billions of components, EDA tools are essential for their design.

Software for PCB layout can often be used to generate perfboard layouts as well. In this case, the designer positions the components so all leads fall on intersections of a 0.1 inches (2.54 mm) grid. When routing the connections more than 2 copper layers can be used, as multiple overlaps are not a problem for insulated wires.

Printed circuit board board to support and connect electronic components

A printed circuit board (PCB) mechanically supports and electrically connects electronic components or electrical components using conductive tracks, pads and other features etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate. Components are generally soldered onto the PCB to both electrically connect and mechanically fasten them to it.

Once the layout is finalized, the components are soldered in their designated locations, paying attention to orientation of polarized parts such as electrolytic capacitors, diodes, and integrated circuits. Next, electrical connections are made as called for in the layout.

One school of thought is to make as many connections as possible without adding extra wire. This is done by bending the existing leads on resistors, capacitors, etc. into position, trimming off extra length, and soldering the lead to make the required electrical connection. Another school of thought refuses to bend the excessive leads of components and use them for wiring, on the ground that this makes removing a component later hard or impossible, e.g. when a repair is needed.

If extra wires need to be used, or are used for principal reasons, they are typically routed entirely on the copper side of perfboards, because, as opposed to stripboards, nearby holes aren't connected, and the only hole in a pad is already occupied by a component's lead. Wires used range from isolated wires, including verowire (enameled copper wire with a polyurethane insulation supposed to melt when soldered), to bare copper wire, depending on individual preference, and often also on what is currently at hand in the workshop.

Stripboard

Stripboard is the generic name for a widely used type of electronics prototyping board characterized by a 0.1 inches (2.54 mm) regular (rectangular) grid of holes, with wide parallel strips of copper cladding running in one direction all the way across one side of the board. It is commonly also known by the name of the original product Veroboard, which is a trademark, in the UK, of British company Vero Technologies Ltd and Canadian company Pixel Print Ltd. In using the board, breaks are made in the tracks, usually around holes, to divide the strips into multiple electrical nodes. With care, it is possible to break between holes to allow for components that have two pin rows only one position apart such as twin row headers for IDCs.

For insulated wires thin solid core wire with temperature-resistant insulation such as Kynar or Tefzel is preferred. The wire gauge is typically 24 - 30 AWG. A special stripping tool can be used, incorporating a thin steel blade with a slit that the wire is simply inserted into and then pulled loose, leaving a clean stripped end. This wire was developed initially for circuit assembly by the wire wrap technique but also serves well for miniature point-to-point wiring on perfboard. Bare copper wire is useful when merging a number of connections to form an electrical bus such as the circuit's ground, and when there is enough space to properly route connections, instead of wiring them rats-nest style.

American wire gauge (AWG), also known as the Brown & Sharpe wire gauge, is a logarithmic stepped standardized wire gauge system used since 1857, predominantly in North America, for the diameters of round, solid, nonferrous, electrically conducting wire. Dimensions of the wires are given in ASTM standard B 258. The cross-sectional area of each gauge is an important factor for determining its current-carrying ampacity.

Intentional solder bridges can be used to connect adjacent pads when necessary. Careful hand–eye coordination is needed to avoid causing inadvertent short circuits.

Circuits assembled on perfboard are not necessarily fragile but may be less impact-resistant than printed circuit boards.

Perfboard differs from stripboard in that each pad on perfboard is isolated. Stripboard is made with rows of copper conductors that form default connections, which are broken into isolated segments as required by scraping through the copper. This is similar to the pattern of default connections on a solderless breadboard. However, the absence of default connectivity on perfboard gives the designer more freedom in positioning components and lends itself more readily to software-aided design than stripboard or breadboard.

CopperCladPerfboard 2.png
Bottom of a copper clad Perfboard with a ground plane
555 timer circuit perforated board.jpg
A 555 timer circuit on perforated board

See also

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Point-to-point construction Method for assembling electrical components

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Breadboard

A breadboard is a construction base for prototyping of electronics. Originally the word referred to a literal bread board, a polished piece of wood used for slicing bread. In the 1970s the solderless breadboard became available and nowadays the term "breadboard" is commonly used to refer to these.

Surface-mount technology method for producing electronic circuits

Surface-mount technology (SMT) is a method for producing electronic circuits in which the components are mounted or placed directly onto the surface of printed circuit boards (PCBs). An electronic device so made is called a surface-mount device (SMD). In industry, it has largely replaced the through-hole technology construction method of fitting components with wire leads into holes in the circuit board. Both technologies can be used on the same board, with the through-hole technology used for components not suitable for surface mounting such as large transformers and heat-sinked power semiconductors.

Flexible electronics

Flexible electronics, also known as flex circuits, is a technology for assembling electronic circuits by mounting electronic devices on flexible plastic substrates, such as polyimide, PEEK or transparent conductive polyester film. Additionally, flex circuits can be screen printed silver circuits on polyester. Flexible electronic assemblies may be manufactured using identical components used for rigid printed circuit boards, allowing the board to conform to a desired shape, or to flex during its use. An alternative approach to flexible electronics suggests various etching techniques to thin down the traditional silicon substrate to few tens of micrometers to gain reasonable flexibility, referred to as flexible silicon.

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Hybrid integrated circuit

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Solder mask

Solder mask or solder stop mask or solder resist is a thin lacquer-like layer of polymer that is usually applied to the copper traces of a printed circuit board (PCB) for protection against oxidation and to prevent solder bridges from forming between closely spaced solder pads. A solder bridge is an unintended electrical connection between two conductors by means of a small blob of solder. PCBs use solder masks to prevent this from happening. Solder mask is not always used for hand soldered assemblies, but is essential for mass-produced boards that are soldered automatically using reflow or solder bath techniques. Once applied, openings must be made in the solder mask wherever components are soldered, which is accomplished using photolithography. Solder mask is traditionally green but is now available in many colors.

In-circuit test (ICT) is an example of white box testing where an electrical probe tests a populated printed circuit board (PCB), checking for shorts, opens, resistance, capacitance, and other basic quantities which will show whether the assembly was correctly fabricated. It may be performed with a bed of nails type test fixture and specialist test equipment, or with a fixtureless in-circuit test setup.

Pad cratering is a mechanically induced fracture in the resin between copper foil and outermost layer of fiberglass of a printed circuit board (PCB). It may be within the resin or at the resin to fiberglass interface.

Veroboard

Veroboard is a brand of stripboard, a pre-formed circuit board material of copper strips on an insulating bonded paper board which was originated and developed in the early 1960s by the Electronics Department of Vero Precision Engineering Ltd (VPE). It was introduced as a general-purpose material for use in constructing electronic circuits - differing from purpose-designed printed circuit boards (PCBs) in that a variety of electronics circuits may be constructed using a standard wiring board.