Printed Circuit Board Glossary

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  • Active Components

    This term refers to a type of component that is dependent on the flow direction of an electrical current. For example, a transistor, rectifier or valve would be considered active.


    Short for any layer inner via hole, this is a type of technology used to build multi-layer BUM PCBs. This method uses a solder to create an electrical connection between PCB layers. ALIVH often replaces traditional vias and is a useful production method for creating high-density BUM PCBs.

  • Analog Circuit

    It refers to circuits processing analog signals (continuous and variable signal). The output is non-binary within this type of circuit.

  • Annular Ring

    This term refers to the copper pad area that is left after a hole is drilled through it. This ring is measured from the edge of the pad to the edge of the hole and is an important consideration in PCB design, as it allows an electrical connection to be made from one side of the hole to the other.

  • Anti-Solder Ball

    This type of technology is commonly applied in SMT production lines with the goal of limiting the amount of tin involved in the stencil process. This is done by making a stencil on the board and creating openings at places where the solder ball tends to be produced so that the tin paste will flow to the openings.

  • AOI

    Short for automated optical inspection, AOI refers to a type of inspection method used to find potential problems concerning soldering performance in multi-layer PCBs with components mounted on. The AOI equipment finds these issues by capturing images of the inner PCB surfaces, looking for any possible issues in terms of displacement, polarity etc.

  • AQL

    Short for acceptance quality limit, AQL refers to the acceptable number of defective boards produced within a production run. These are identified, counted and removed during inspection. AQL is an important figure for monitoring the quality of an assembler's production practices.

  • Array

    This word refers to the combination of multiple copies of the same PCB into a connected matrix of boards. An array may also be referred to as a panelized, stepped out or palletized PCBs. By assembling boards this way, the assembly process can be completed much more quickly. The Array # Up, in turn, refers to how many PCBs are included in the array.

  • Aspect Ratio

    Aspect ratio refers to the ratio between a PCB's thickness and diameter of its minimum via. It's best to keep aspect ratios low to improve plating quality and minimize potential via failures.

  • Assembly

    A process involving a series of procedures where components and accessories are placed on a PCB, resulting in a functional board.

  • Assembly Drawing

    An assembly drawing is a reference depicting the assembly requirements of a PCB. These drawings will usually include the placements of components as well as the construction technologies, methods and parameters needed to make it happen.

  • Assembly House

    A name used to refer to a manufacturing facility where PCBs and components are assembled. These houses will usually contain PCBA equipment such as a printer, mounter, reflow oven, and more.


  • Back Drilling

    Primarily applied in multi-layer PCB fabrication, back-drilling helps improve signal integrity by removing stubs from plated through-holes. These stubs are unnecessary portions of via that extend into the hole, potentially causing reflections and other disturbances that damage signals.

  • Backplane

    This is a supporting plane on a circuit board that plays an insulating role.

  • BGA

    Short for ball grid array, this is a type of component packaging used in integrated circuits (ICs) for surface mounting. They can ensure high-speed efficiency since they use columns of balls instead of pins. BGAs are usually used to mount devices like microprocessors on PCBs permanently.

  • Bare Board

    This term refers to a circuit board with no components mounted on it.

  • Blind Via

    A blind via is a through-hole that connects inner layers, but it can't be seen from the exterior of the PCB.

  • Board

    This is a shortened term for printed circuit board. This word also indicates the substrate upon which the PCB is printed. The board is an important electronic part, acting as a carrier for an electric connection between electronic components.

  • Board House

    This is another name for the facility where PCB boards are fabricated.

  • Board Type (Single Unit and Panel)

    This indicates the manufacturing method of a PCB in terms of volume. Usually, a board is classified into one of two types: single unit or panel. In single unit manufacturing, PCBs are fabricated one by one. In panel manufacturing, on the other hand, multiple units of PCBs are manufactured in a single panel.

  • Body

    A word used to describe the central section of an electronic component. It does not include the component's pins, leads or accessory parts.

  • Buried Resistance Board

    The term refers to a printed circuit board with resistors buried inside. This design improves the integrity of resistant components to improve the overall function and reliability of the PCB.

  • Buried Via

    This term is used to refer to a via connecting a top layer to one or more inner layers. In other words, a buried via can only be seen from one side of the board when looking at it from the outside.


  • Cable

    Another word for a wire that is capable of transmitting electricity or heat.

  • CAD

    An acronym for computer-aided design, CAD refers to a designer's use of computer and pattern equipment to develop and implement a PCB layout. The result is a three-dimensional graphic of the design, which, in this case, is the layout of a PCB.

  • CAE

    An acronym for computer-assisted engineering that refers to schematic software packages used to develop and visualize PCB designs.

  • CAM Files

    CAM is an acronym for computer-aided manufacturing, and the files produced by this software are used for PCB manufacturing. There are multiple types of CAM files, including Gerber files for photoplotters and NC Drill files for NC Drill machines. These files are usually sent off to board and assembly houses for refinement and eventual manufacturing.

  • Carbon Mask

    This is a type of conductive carbon paste that is added to the surface of a pad. Made with a combination of resin and carbon toner, carbon masks are heat-cured and are typically applied to jumpers, keys, etc.

  • Ceramic Substrate Printed Board

    This type of board is made with a ceramic substrate, to which other materials are bonded with alumina or aluminum nitride. The primary selling points for ceramic substrate boards are their excellent insulation capabilities, thermal conductivity, soft solderability and adhesive strength.

  • Check Plots

    This is a list of check items that are based on which quality control inspection or test is implemented.

  • COB

    Shorthand for chip-on-board, this term is a type of bare chip SMT technology. COB involves directly mounting integrated circuits to a PCB instead of packaging them first. Common in mass-produced gadgets and toys, COB can be identified by a black glob of plastic on a PCB, called a glob top. Underneath the glob, the chip connects to the board with fine wires.

  • Circuit

    It refers to a conductive loop composed of metal leads and electronic components. It falls into one of two categories: DC circuits and AC circuits.

  • Coating

    A coating is a solid continuous film that either protects, insulates or decorates the PCB.

  • Component

    Alternatively called electronic components or parts, components are basic pieces that can be used to build electronic equipment and devices. Examples include resistors, capacitors, potentiometers, valves, radiators, etc.

  • Component Hole

    This is a plated hole in a PCB that is made for a component. These holes are intended to facilitate either a component pin, termination or wire with an electric connection.

  • Component Library

    It's a collection of components as represented in a CAD software system. It's stored in a computer data file for later use.

  • Component Side

    This refers to the side of a PCB that contains components. The opposite side contains soldering points for components.

  • Connector

    This term refers to a transmitting component that connects two or more active components in an assembly. Usually, connectors consist of a plug and receptacle, which can be easily joined and separated.

  • Copper Weight

    This term is used to indicate thickness of copper foil on each layer of a PCB. It's typically expressed in ounces of copper per square foot.

  • Countersink Holes

    These are cone-shaped holes that are drilled into a PCB. To allow a countersunk screw to sit flush with the PCB surface.

  • Counterbored Holes

    These cylindrical holes are meant to be used with a fastener so that the fastener sits flush with the PCB surface.

  • Cutout

    This is a groove that is dug on a PCB.


  • Daughter Board

    The "daughter" of a "mother" board, a daughter board contains plugs, pins, sockets and connectors and plays a big role in internal connections for electronic devices and computers.

  • Decal

    Another word for a graphic representation of an electronic component, which can also be called a footprint.

  • Digital Circuit

    The alternative to an analog circuit. Digital circuits operate in a binary fashion like a switch, exhibiting one of two results as a consequence of an input. This is a typical circuit for computers and similar equipment.

  • DIP

    An abbreviation for a dual in-line package, a DIP is a kind of housing for integrated circuits. This housing will typically come in the form of a molded plastic container with two rows of attachment pins.

  • Double-Sided PCB

    A type of PCB that features traces and pads on both sides, rather than a single side.

  • DRC

    An acronym for design rule check, this is a software verification of a PCB layout. These are often used on PCB designs before production to ensure the design doesn't contain any potential sources of error, like small drill holes or traces placed too close together.

  • Drill Hits

    This is another way to refer to where holes will be drilled in a PCB design.

  • Dry Film Solder Mask

    This is a type of solder mask film that is applied to a printed board that results in a higher resolution mask with finer line designs. This method tends to be more expensive than liquid solder masks.


  • Edge Connector

    This type of connector is designed for the edge of a PCB, and it is most often used to facilitate an add-on card.

  • Edge Plating

    This is a term used for copper plating that stretches from the top to the bottom of a surface and along the edges of a board, allowing for edge soldering and connections.

  • Electroconductive Paste Printed Board

    This term is used to describe PCBs that are manufactured using a silkscreen printing method. The process involves applying an electroconductive printing paste to set traces and to implement stable through-hole connections.

  • EMC

    An acronym for electromagnetic compatibility, EMC refers to the capability of a piece of equipment or system to run without producing excessive electromagnetic interference. Too much electromagnetic interference can interfere with or damage other pieces of equipment within the same electromagnetic environment.

  • ESD

    A shorthand for electrostatic discharge, which is caused by static electricity.

  • External Layer

    Also called an outer layer, an external layer is a layer on the outside of copper to which components attach.


  • Fabrication Drawing

    This drawing is a way for designers to communicate a PCB design to engineers and workers. It will typically include an illustration of the board, locations and information about holes to be drilled, notes about the materials and methods involved, etc.

  • Fine Pitch

    This term refers to a class of chip packages with micro-spacing between leads, typically below 0.050 inches.

  • Finger

    These are metal pads found along the edge of a board. These are typically used when trying to connect two circuit boards together to expand the capacity of a computer, for example.

  • First Article

    This is what the first manufactured board is called. First articles are usually produced in small groups before volume production begins so that designers and engineers can inspect the product for potential errors or performance problems.

  • FR4

    This is a material rating for a flame-resistant material. It also refers to the most commonly used PCB substrate material. The name specifies that the resin material is capable of automatically extinguishing when it is aflame.

  • Functional Test

    Alternatively called behavioral test, functional test is designed to determine how well a product's attributes meet design demands.


  • Gerber File

    A type of CAM file used to control a photoplotter. It's a standard way of communicating board specifications with manufacturers.

  • Glob Top

    This refers to a "glob, " a small ball of non-conductive plastic used to protect the chip and wire bonds on a COB. The glob is usually black in color and is resistant to thermal expansion, which prevents temperature changes from damaging the connection between the glob and the board.

  • Gold Fingers

    These are connectors found on the edge of a PCB after the board has been plated with gold. Hard, smooth and flat, these fingers are excellent conductors, supporting edge-to-edge connections.

  • Grid

    "Grid" is another term for an electrical grid, an interconnected electrical network that transmits power.


  • Half-Cut/Castellated Holes

    This refers to holes that are drilled on the edge of a board and plated, resulting in a half-circle hole on the edge of the PCB. This is common for PCBs designed for microchip testing.

  • HDI

    An acronym for high-density interconnector, an HDI is a type of PCB fabrication technology. It uses micro blind via technology to manufacture PCBs with high trace density.

  • Header

    The portion of a connector assembly that mounts directly to the printed circuit.


  • IC

    Short for integrated circuit, an IC is also called microcircuit, microchip or chip. Essentially, IC describes a method for miniaturizing circuits, especially for semiconductor devices.

  • Internal Layer

    This term refers to the inner layers in multi-layer PCBs. These inner layers are mostly signal layers.

  • IPC

    An abbreviation of Institute of Printed Circuits, a worldwide non-profit association dedicated to the design of PCB wiring. The group helps enterprises achieve greater business success by helping them meet rigorous manufacturing standards, which, in turn, improve overall quality standards.


  • Kapton tape

    Alternatively called polyimide tape, this electrically insulating tape has numerous useful features, including heat resistance, inextensibility and thinness.


  • Laminate

    This term refers to the combination of different materials through heating, adhesive and welding methods to create a new material with multiple layers. The resulting material has greater strength and stability than the individual materials combined to create the laminate.

  • Laser Photoplotter

    Alternatively called a laser plotter, this type of photoplotter creates a finely-lined raster image of the end product. The result is a high-quality, highly accurate plot.

  • Layer-to-Layer Spacing

    This is the distance between PCB layers. The lower the spacing, the more difficult the manufacturing process will be.

  • Lead

    Another word for a terminal on a component.

  • Legend

    This is a shorthand guide for marking component names and positions. Legends help ease the assembly and maintenance processes.

  • LPI

    Shorthand for Liquid Photoimageable, an LPI is a liquid solder mask that is sprayed on a PCB. This method is more accurate, thinner than a dry film solder mask and more affordable.


  • Mark

    A term used to refer to a set of patterns for optical localization. Marks can be classified into PCB Marks and local Marks.

  • Membrane Switch

    A membrane switch is applied to the front of a finished PCB. It indicates functions of the PCB and components, such as key functions, indicators and other parts. The membrane also provides protection for the PCB in the form of waterproofing and humidity protection.

  • Metal Base/Core Printed Board

    Metal core PCB refers to a type of PCB with a core material made of metal instead of plastic, resin or FR4 material.

  • Mil

    A "mil" is another way to say a thousandth of an inch. It's also the equivalent of a "thou.

  • mm

    "mm" is another way to express a millimeter or a thousandth of a meter.

  • Motherboard

    This is the main board in a computer or electric device. The motherboard carries key interconnections and components that support the primary functions of the device.

  • Mounting Hole

    This hole is intended to secure the PCB to its final location in a device. To ensure there is no interference, all mounting holes are non-conductive and unplated.

  • Multi-Layer PCB

    This is a type of PCB with at least three conductive layers of trace and components.

  • Multimeter

    A testing tool used to measure electrical values like current, resistance and voltage.

  • Multi-Wiring Printed Board

    An equivalent to a multi-layer printed circuit board, this term refers to PCBs with multiple layers of trace, with dielectric layers between each.


  • NC Drill

    This is a more common name for a Numeric Control drill machine. This type of machine is what assemblers use to drill holes in PCBs.

  • Node

    This is a pin or lead that is connected to at least one wire.

  • NPTH

    An acronym for non-plated through hole, NPTH refers to a hole with no plated copper on the hole wall. This means no electric connections can be made using the walls of this hole.


  • Open

    This is a short way of saying "open circuit, " which is a break in an electrical circuit's continuity. This prevents current from flowing and can disrupt the proper function of a PCB.


  • Pad

    This is one of the most basic composition units of a PCB assembly. A pad is a contact point used to connect components with a via and is the point to which the components are soldered.

  • Panel

    A panel is a combination of boards produced simultaneously to improve efficiency during the manufacturing process. Once the process is finished, these panels are typically broken apart into their singular units before being used.

  • Panelize

    This is the act of grouping multiple PCBs into a panel to improve manufacturing efficiency. An alternative term is Panelization Type.

  • Part Number

    This is an identification method used in industry to differentiate parts from one another. It's also used to identify specific parts, which is helpful in identifying problematic assembly batches and preventing incorrect product applications.

  • Part

    This is another word for a component, or a basic piece of electric equipment, such as a resistor, capacitor, potentiometer, valve, radiator, etc.

  • PCB Base Material

    The material upon which the PCB is built. The PCB base material is typically composed of resin, metal, ceramic or another material with thermal and electric properties that support the PCB's final function.

  • PCB Database

    All the data that is or could be used for a PCB design. This data is usually stored in a computer file.

  • PCB

    An abbreviation of Printed Circuit Board, a PCB is a board that contains a conductive material and components, which act in synchrony to produce a designed response. PCBs rely on electrical circuits, which are either printed or soldered onto the board to elicit the desired result. Printed circuit boards are available in a wide variety of shapes, sizes and purposes to suit any industry or application.

  • PCBA

    This is an acronym for Printed Circuit Board Assembly, where a company solders components to boards.

  • Peelable Solder Mask

    A solder mask or layer of solder mask that can be peeled from the board.

  • Photoplotter

    A device used in manufacturing to produce artwork onto film by plotting objects instead of images.

  • Pick-And-Place

    A method of SMT assembly where a machine automatically picks up SMDs and places them in the correct positions on the board.

  • Pin

    A terminal on a component. It is also called a lead.

  • Pitch

    The distance between pin centers of SMDs.

  • Plated-Through Hole

    Alternatively called a PTH, this is a procedure in which a through-hole is plated so that the hole wall can be conductive. This is often used as a contact point for through-hole components and can be used as a via.

  • Prepreg

    Also called PP, is the key material for multi-layer PCB manufacturing. it is primarily composed of resin and strengthening material that is then classified into glass-fiber cloth, paper base, compound material etc.

  • Press Fit Holes

    This is a hole through which a contact terminal can be pressed into a PCB.

  • Printed Wiring

    Printed Wiring

  • Printing

    Part of the PCB manufacturing process where a circuit pattern is printed on the board.

  • PWB

    An acronym for Printed Wiring Board, which is another name for a PCB.


  • Reference Designator

    Alternatively called "Ref Des, " this is the name of a component on a PCB. Typically, the component name begins with a letter or two, indicating the component class, followed by a number. These designators are usually printed on the silkscreen to help identify each component.

  • Reflow

    This is the process of melting solder to create a joint between a pad and a component or lead.

  • RF

    Short for radio frequency, RF is an electromagnetic frequency ranging between 300KHz and 300GHz. RF can also be a type of high-frequency electromagnetic signal.

  • RoHS

    Alternatively known as the Restriction of Hazardous Substances, RoHS is a European environmental protection law. Many global companies must follow RoHS standards to sell products in the EU.

  • Route/Track

    This is the layout of a PCB's wiring structure, which is important for the proper function of the PCB. As a verb, the act of routing means designing such wiring structures.


  • Schematic

    A technical drawing that illustrates the connections between PCB components. Schematics will often include abstract representations of components instead of pictures and is an important first step in PCB design.

  • Short

    This is an alternative way to say "short circuit, " which is a connection with low resistance, resulting in excess current at the connecting point. This can cause serious problems in the PCB, including failure.

  • Silkscreen

    This is a layer of epoxy ink applied to a PCB that contains component names and positions. The labels included on silkscreens help to direct workers through the assembly process. Typically, silkscreens are white, which helps the labels stand out against the PCB's solder mask.

  • Single-Sided PCB

    A PCB design with traces and pads included on only one side of the board.

  • Slot Hole

    Non-round holes on a PCB that may or may not be plated. These are often required for specific components but are costly due to the labor needed to cut them.

  • SMD

    Short for surface mount devices, it refers to components designed to be soldered on the surface of PCBs, rather than through a thru-hole.

  • SMT

    Short for surface mount technology, this type of assembly technology directly solders SMDs to the surface of a PCB, rather than running components through thru-holes. This allows the board to function without drilling holes through it and also helps improve component density on the surface of the PCB.

  • Solder Mask/Solder Resist

    This is a layer of material, usually consisting of an epoxy resin, which isn't compatible with solder. This material is applied to the entire PCB, except those areas where content needs to be soldered. This process helps to physically and electrically insulate traces, preventing shorts. Solder masks are often green in color, though red and black are also common.

  • Solder Side

    This is the opposite of the component side and is usually regarded as the bottom side.

  • Spacing

    This term refers to the distance between wires on a PCB.

  • Substrate

    This is another word for "PCB base material", the primary material for PCB fabrication. Generally, this material can be flexible or rigid and can be made of epoxy, metal, ceramic or other materials. The function of the end PCB will usually determine which substrate will be used for the project.

  • Supported Hole

    This is a via with pads on both sides of the PCB. It's also plated inside the via. This means the entire hole can support functions relating to thermal or electrical conductivity.

  • Surface Finish

    Since copper tends to oxidize in natural environments, a surface finish protects the layer from doing so. Oxidation can cause the tin paste to fail or solder incorrectly. The primary types of surface finishes include HASL, ENIG, IMAG, OSP and others.


  • Tented Via

    This is a type of via that has a dry film solder mask covering both its pad and its plated-thru hole. This solder mask insulates the via completely, protecting the PCB against shorts. Some vias are tented only on one side to allow for testing on the other.

  • Thou

    This is shorthand for a thousandth of an inch. It's another way to say "mil. "

  • Through-Hole/Thru-Hole

    This refers to a hole passing through at least two layers of a multi-layer PCB. It's also used as a descriptor for components with parts or pins that run through a board to be soldered to another side.

  • Trace/Track

    This refers to the copper path printed on a PCB. It functions similarly to an electrical wire, connecting components on a PCB board. The word "trace" is also used to refer to a segment of the path.

  • Tracing

    This term refers to the width of a PCB's wires.


  • UL

    UL stands for Underwriter's Laboratories, Inc., a renowned company specializing in establishing safety standards and independently assessing products according to these standards.

  • Unsupported Hole

    This type of hole has a pad on the solder side, but no pad on the component side. There is also no metal layer inside the hole. This means the hole has no conductive reinforcement.


  • Vector Photoplotter

    Alternatively called a vector plotter or Gerber Photoplotter, this type of photoplotter draws a plot line by line using light manipulation technology. This method can produce larger plots, but it is also much slower than the more modern laser photoplotter method.

  • Via

    This term refers to plated through-holes that connect signals between traces on different layers of a PCB. These holes have conductive copper interiors to maintain an electrical connection.

  • Via Filled With Resin/Via Plugged

    This is a via that is filled with an epoxy resin. Once filled, copper can be soldered to the surface of the resin without influencing the final product.

  • Via in Pad

    Also called a thru-hole on the pad, a via in pad functions as an electric connection between layers. It is useful for multi-layer components or for fixing the positions of components.

  • V-Scoring

    This is an incomplete cut through a panel, which is often used to help break apart panels of PCBs into single units.


  • Wire

    This refers to a conductive cable that can transmit electricity or heat. It also refers to a route or track on a printed circuit board.

PCB base materials

PCB Partner knows that there are many options concerning base materials and with our technical knowledge we can help guide and assist you in terms of material selection and material specifications.

Rigid material

How should material be specified?

Every well-known manufacturer of material will have their product categorized in accordance with IPC 4101 (specification for base materials for rigid and multilayer printed boards) with the aim of this specification being to identify and categorize performance characteristics. Using this categorization approach is ideal as it defines the characteristics of the base material, in detail, and allowing the factory to follow the IPC-4101-xxx categorization enables them to select wisely thus ensuring performance is nothing less than expected.

If you you wold like more information on IPC 4101 or material specification methods, then please contact PCB Partner who will be happy to help.

Key factors in specifying material characteristics

When considering the performance characteristics of the base material, consideration should be given to both the mechanical properties (specifically in relation to how the material shall perform during heat cycling / soldering operations) and also the electrical properties associated with the material. These are typically regarded as the most common factors for selection of standard products. This comment is based upon all material being considered able to meet UL flammability rating V”0.

Key material characteristics

·         CTE – Z axis (Co-efficient of thermal expansion): This is a measure of how much the base material will expand when heated. Measured as PPM/degree C (both before and after Tg) and also in % over a temperature range.

·         Td (Decomposition temperature): This is the temperature at which material weight changes by 5%. This parameter determines the thermal survivability of the material.

·         Tg (Glass transition temperature): The temperature at which the material stops acting like a rigid material and begins to behave like a plastic / softer.

·         T260 (Time to delamination): This is the time it take for the base material to delaminate when subjected to a temperature of 260 degrees C.

·         T288 (Time to delamination): This is the time it take for the base material to delaminate when subjected to a temperature of 288 degrees C.

·         Dk (Dielectric constant): The ratio of the capacitance using that material as a dielectric, compared to a similar capacitor which has a vacuum as its dielectric.

·         CTI (Comparative tracking Index): A measure of the electrical breakdown properties of an insulating material. It is used for electrical safety assessment of electrical apparatus. Rating can be seen below.

Tracking Index (V)


600 and   greater


400   through 599


250   through 399


175   through 249


100 through   174


< 100


The table below is an extract of certain characteristics from IPC-4101 classifications, highlighting some of the details already referenced.











Tg (min) C










Td (min) C










CTE Z 50-260 C










T260 (min) minutes










T288 (min) minutes










Fillers > 5%










Dk/Permittivity (max)










Insulated Metal Substrate (IMS) – effective technology for heat dissipation

New opportunities with insulated Metal Substrate

For greater amounts of energy or local thermal loads, e.g in modern constructions with high intensity LEDS, IMS technology can be used. The abbreviation, IMS, stands for “Insulated Metal Substrate.” This is a PCB built on a metal plate – normally aluminium – on which a special prepreg is applied, the primary qualities of which are an excellent capacity for heat dissipation and great dielectric strength against high voltages. Together with EBV and a number of other companies, NCAB has taken part in the development of a demo product. The aim here is to attract the market´s attention to the opportunities for combining high intensity LEDs with IMS technology.

The most important constituent – the heat-conducting prepreg – is a ceramic or boron-filled material, specially produced to be able to dissipate large amounts of heat. Its heat conductivity is often 8-12 times greater than that of an FR4.

The advantages of IMS PCBs for heat dissipation

An IMS PCB can be designed with a very low thermal resistance. If, for example, you compare a 1.60 mm FR4 PCB to an IMS PCB with a 0.15 mm thermal prepreg, you may well find the thermal resistance is more than 100 times that of the FR4 PCB. In the FR4 product it would be very difficult to dissipate any larger amount of heat.

When considering the performance characteristics of the base material, consideration should be given to both the mechanical properties (specifically in relation to how the material shall perform during heat cycling / soldering operations) and also the electrical properties associated with the material.

If you have any specific questions about base materials, please contact PCB Partner.

Material recommendations

Material recommendations for different conditions and technologies can be seen below. However it is important to note that they should be viewed as very “rough” recommendations. Equally, we recommend that the customer evaluate their process and define the factors that the materials are required to withstand, such as peak temperature and take into account the demands for Td, T260 and T288.

Materials according to IPC 4101/121 (min. Tg 130 Deg. C)

Total   thickness

≤ 1.60mm

Number of   layers

1 to 4


< 70µm

Material according to IPC 4101/99 or /124 

Total   thickness

≤ 2.40mm

Number of   layers

6 to 12


≤ 70µm

Blind /   Buried vias / µvias


Material according to IPC 4101/126 or /129  

Total   thickness


Number of   layers



> 70µm

Blind /   Buried vias / µvias


PCB Surface finishes

A PCB surface finish can be either organic or metallic in nature.  Typically, the decisive factors when it comes to selecting the most suitable finish is the end application, the assembly process and the design of the PCB itself. Below you can find a brief summary of the most common finishes.

ENIG Immersion gold / Electroless Nickel Immersion Gold


1.      Immersion finish = excellent flatness

2.      Good for fine pitch / BGA / smaller components

3.      Tried and tested process

4.      Wire bondable


1.      Expensive finish

2.      Black pad concerns on BGA

3.      Can be aggressive to soldermask larger soldermask dam preferred

4.      Avoid soldermask defined BGAs

5.      Should not plug holes on one side only

OSP (Organic Solderability Preservative)


1.      Excellent flatness

2.      Good for fine pitch / BGA / smaller components

3.      Inexpensive / Low cost

4.      Can be reworked

5.      Clean, environmentally friendly process


1.      Very sensitive to handling gloves must be used and scratches avoided

2.      Short operating window between assembly stages

3.      Limited thermal cycles so not preferred for multiple soldering processes (>2/3)

4.      Limited shelf life not ideal for specific freight modes and long stock holding

5.      Very difficult to inspect

6.      Cleaning misprinted solderpaste can have a negative effect on the OSP coating

HASL Tin/Lead hot air solder level


1.      Excellent solderability

2.      Inexpensive / Low cost

3.      Allows large processing window

4.      Long industry experience / well known finish

5.      Multiple thermal excursions


1.      Difference in thickness / topography between large and small pads

2.      Not suited for < 20mil pitch SMD & BGA

3.      Bridging on fine pitch

4.      Not ideal for HDI products

LF HASL Lead Free hot air solder level


1.      cellent solderability

2.      Relatively inexpensive

3.      Allows large processing window

4.      Multiple thermal excursions


1.      Difference in thickness / topography between large and small pads but to a lesser degree than SnPb

2.      High processing temperature 260-270 degrees C

3.      Not suited for < 20mil pitch SMD & BGA

4.      Bridging on fine pitch

5.      Not ideal for HDI products

Immersion Sn Immersion Tin


1.      Immersion finish = excellent flatness

2.      Good for fine pitch / BGA / smaller components

3.      Mid range cost for lead free finish

4.      Press fit suitable finish

5.      Good solderability


1.      Very sensitive to handling gloves must be used

2.      Tin whisker concerns

3.      Aggressive to soldermask soldermask dam shall be 5 mil

4.      Baking prior to use can have a negative effect

5.      Not recommended to use peelable masks

6.      Should not plug holes on one side only

Immersion Ag Immersion Silver


1.      Immersion finish = excellent flatness

2.      Good for fine pitch / BGA / smaller components

3.      Mid range cost for lead free finish

4.      Can be reworked


1.      Very sensitive to handling / tarnishing / cosmetic concerns gloves must be used

2.      Special packaging required if packaged opened and not all boards used, it must be resealed quickly.

3.      Short operating window between assembly stages

4.      Not recommended to use peelable masks

5.      Should not plug holes from one side only

6.      Reduced supply chain options to support this finish

Comparison of cost and solderability

Cost: ENIG > Immersion silver> Immersion tin > HASL > OSP.

Actual solderability:  HASL > OSP > ENIG >Immersion silver >Immersion tin

Characteristics of common surface treatment methods

physical property


Immersion silver

Immersion Tin


Immersion gold (ENIG)

Shelf life (month)






Reflow times












Process Complexity






Process temperature






Thickness range (um)





0.05-0.2 Au

3-5 Ni

Flux compatibility






Environmental protection







Thickness Nonuniformity

Easily scratched

Short storage

Sensitive to environment

Easily-broken interface

General introduction of Aluminum PCB

General introduction of Aluminum PCB


Among all Metal core PCBs,Aluminum PCBs is the most common type - the base material consists of aluminum core with standard FR4. It features a thermal clad layer that dissipates heat in a highly efficient manner, while cooling components and increasing the overall performance of the products. Currently, Aluminum Backed PCBs is regarded as the solution to high power and tight tolerance applications.


Advantages of Aluminum PCB


1.Environmentally Friendly: Aluminum is non-toxic and recyclable. Manufacturing with aluminum is also conducive to conserving energy due to its ease of assembly. For printed circuit board suppliers, using this metal helps maintain the health of our planet.

2.Heat dissipation: High temperatures can cause severe damage to electronics, so it is wise to use a material that can help dissipate heat. Aluminum can actually transfer heat away from vital components, thus minimizing the harmful effect it could have on the circuit board.

3.Higher durability: Aluminum provides strength and durability to a product that ceramic or fiberglass bases cannot. Aluminum is a sturdy base material that can reduce accidental breakage during manufacturing, handling, and everyday use.

4.Lightweight: For its incredible durability, aluminum is a surprisingly lightweight metal. Aluminum adds strength and resilience without adding on any additional weight.


Application of Aluminum PCB

 timg (1).jpg

1. Audio device: Input, output amplifier, balanced amplifier, audio amplifier, pre-amplifier,power amplifier.

2. Power Supply: Switching regulator, DC / AC converter, SW regulator, etc.

3. Communication electronic equipment: High-frequency amplifier, filtering appliances,transmitter circuit

4. Office automation equipment: Motor drive, etc.

5. Automobile: Electronic regulator, ignition, power supply controller, etc.

6. Computer: CPU board, floppy disk drive, power supply devices, etc.

7. Power Modules: Inverter, solid state relays, rectifier bridges.

8. Lamps and lighting: As the advocated promotion of energy-saving lamps, a variety of colorful energy-saving LED lights are well received by the market, and aluminum pcb used in LED lights also begin large-scale applications.

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What is High Frequency (HF) PCB?

What is High Frequency (HF) PCB?

Electronic devices with high frequency is the developing tendency nowadays, especially in wireless network. Satellite communication growing rapidly, information products move towards high speed and high frequency. Thus developing new products always need to use high frequency substrate, satellite system, mobile telephone receiving base station and so on, these communication products must use high frequency PCB.

 High Frequency (HF) PCB.jpg

The features of high frequency PCB.

1. DK should be small and stable enough, usually the smaller the better, high DK may lead to signal transmission delay.

2. DF should be small, which mainly affect quality of signal transmission, the smaller DF could make smaller signal wastage accordingly.

3. The thermal expansivity should be the same with copper foil as much as possible, because the difference will lead to copper foil separated in the changes of cold and heat.

4. Water absorptivity must be low, high water absorptivity will affect DK and DF when in the wet environment.

5. Heat resisting property, chemistry resisting, impact endurance, peel off resisting must be good.

Materials used for HF circuit board.

High-frequency board for wireless applications and data rates in the upper GHz range have special demands on the material used:

1. Adapted permittivity.

2.Low attenuation for efficient signal transmission.

3.Homogeneous construction with low tolerances in insulation thickness and dielectric constant.

Generally speaking, high frequency can be defined as frequency above 1GHz. Currently, PTFE material is widely used in high frequency PCB manufacturing, it's also called Teflon, which frequency is normally above 5GHz. In addition, FR4 or PPO substrate can be used to the product frequency among 1GHz~10GHz. These three high frequency substrate have below differences:

With regard to laminate cost of FR4, PPO and Teflon, FR4 is the cheapest one, while Teflon is the most expensive one. In terms of DK, DF, water absorption and frequency feature, Teflon is the best. When product application require frequency above 10GHz, only can we choose Teflon PCB  substrate to manufacture. Obviously, the performance of Teflon is far better than other substrate, However, Teflon substrate has the disadvantage of high cost and large heat resisting property. In order to improve PTFE stiffness and heat resisting property function, a large number of SiO2 or fiber glass as the filling material. On the other hand, due to molecule inertia of PTFE material, which it is not easy to combine with copper foil, thus, it needs to do special surface treatment on the combination side. With regard to combination surface treatment, normally use chemical etching on PTFE surface or plasma etching to plus surface roughness or add one adhesive film between PTFE and copper foil, but these may have influence on dielectric performance.

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High-TG PCBs High Temperature PCB fr4 Material

The Glass Transition Temperature (Tg) is one of the most important properties of any epoxy and is the temperature region where the polymer transitions from a hard, glassy material to a soft, rubbery material.

Circuit board material must flame-resistant, it can’t be burned at a certain temperature and only be soften. The temperature point is called the glass transition temperature (Tg).

The higher Tg point means higher temperature requirement during lamination. And the boards will be hard and crisp, which will affect hole and the electrical properties.

Ordinary PCB materials at high temperatures, not only will be soften, deformation, melting and other phenomena, but also the mechanical and electrical properties decline sharply. 

General fr4 Tg is 130-140 centigrade, moderate Tg is greater than 150-160 centigrade, High-Tg is greater than 170 degrees.

The higher of Tg, the better performance of PCB heat resistance, moisture resistance, chemical resistance, stability and other characteristics.

FR4 is a code name for grade of Epoxy Glass material.

Tg means Glass Transition Temperature.

When the working temperature reaches to the melting point, that means the temperature exceeds the Tg value, the status of pcb material will be changed from glassy to liquid, which will affect the function of pcb. And this value is related to the stability of the pcb dimension.

As usual, made with Tg ≥ 170℃ pcb material, which is called high Tg printed circuit board. With the rapid development of the electronics industry, high Tg material is widely used in computer, communication equipment, precise apparatus and instrument and etc.

The characteristics of High Tg materials are listed below:


  • Higher heat resistance;

  • Lower Z-axis CTE;

  • Excellent thermal stress resistance;

  • High thermal shock resistance;

  • Excellent PTH reliability.

  • Pcbpartner offers some popular High Tg materials:

  • S1000-2 & S1170: Shengyi materials;

  • IT-180A: ITEQ material;

  • TU768: TUC material.

S1000-2 S1000-2B Lead Free Compatible FR-4 High Tg


Lead-free compatible FR-4.0 laminate
Tg170℃(DSC), UV Blocking/AOI Compatible
High Heat Resistance
Lower Z-Axis CTE
Excellent Through-hole Reliability
Excellent Anti-CAF Performance
Low Water Absorption

Low CTE/Hi-Tg/Excellent Thermal Resistance


S1170G S1170GB Halogen Free FR-4 High Tg


Free of constituents such as halogen,antimony,
red phosphorous, toxic gas emission and
no hazardous residue during waste
lead free compatible
High Tg halogen-free,Tg 180℃(DMA)
UV Blocking/AOI compatible
Lower Z-axis CTE

High Tg Halogen-free FR-4


To make high Tg pcb, PCBPartner has the experience and clients are satisfied with our products. If you need, please go to homepage of PCB Instant Quote menu to quote; please contact us for more information about High Tg pcbs.


The LED lighting PCB comes into being with the rapid development of printed circuit PCB industry. Some LEDs were soldered on PCB to created lighting electronic products.


As we all know that LED will generate more heat compared with other electronic parts, which required the PCB to have better ability for dissipating heat. For this special requirements, metal core PCB are frequently used on LED PCB, especially aluminium core PCB. This is because the aluminum PCB typically includes a thin layer of thermally conductive dielectric material that can transfer and dissipate the heat with much greater efficiency than a traditional rigid PCB.

led pcb.jpg

The application of LED PCB

Telecommunications:LED indicators and displays are always used for telecommunications equipment because of the surrounding machinery, the excellent heat transfer ability. So aluminum-based LED PCBs is extremely useful in this application. 

Automotive: Aluminum PCB LEDs also used in cars on indicators, in headlights and brake lights, and other applications. The durability and competitive price makes these aluminum PCBs ideal within the automotive industry.  

Computer: LED displays and indicators are becoming more and more common within computer applications, and the heat sensitivity of computer machinery makes aluminum PCB LEDs the ideal solution. In addition to LED applications, computer parts like power devices and CPU boards are commonly use aluminum PCBs because of their ability to dissipate and transfer heat.

Medical: Lighting tools used in surgeries and medical examinations commonly use high-powered LED lights, and these LED lights often use aluminum PCBs. This is primarily due to the durability and heat transfer capabilities of aluminum PCB LEDs — this ensures medical equipment is functioning properly regardless of the number of patients cycling through a medical office. In addition to lighting tools, medical scanning technology often uses aluminum PCBs as well.   

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