| Circuit board vocabulary | |
| Blind via | Connects outer layer with inner layer; exposed only on one side of the board. |
| Buried via | Connects internal layers without being exposed on either surface. |
| Chip on board | Integrated circuits glued and wire-bonded to boards (foregoing packaging) culminating in a chip with fine wires bonded to both it and landing pads. |
| LPI | Liquid photoimageable solder mask. For purpose of controlling deposition, a mask is applied through the use of photographic imaging techniques. |
| Plane | Copper layer connected to the ground that covers most of the board layer it inhabits. |
| Substrate | Surface adhesive substance spread for bonding or coating, this material (most commonly FR-4) is a non-conductive carrier of copper traces. |
| Surface finish | Selected by customer; assembly component process determines plating for top and bottom layers; factors considered: application and shelf life. |
| Trace | Copper strip used for carrying signal between two points on a circuit board. |
| Via | Plated-through hole between one or more layers transferring heat from top layer to inner and/or bottom layers connected to internal ground plane. |
| Heavy copper | At least three ounces of total copper used in the inner and outer layers. |
| Etch-down | Start with one ounce base copper than desired finished copper weight and plate up to the target copper weight. |
| Plate-up | Start with Cu weight significantly less than target and repeat image through plating processes until achieving target Cu weight. |
| Conductor | A single conductive path in a conductive pattern. |
| Silkscreen | Non-conductive layer. |
| Dielectric | Non-conductive insulating layer between conducting Cu layers to keep them isolated from one another. |
| Component | Part(s) used to perform a design function. |
| Annular | The area of the pad surrounding the via. |
| Fiducial | Provides common measurable point for component mounting in regards to a land pattern. |
| Tented via | Via covered with soldermask that bridges over the opening. |
| Copper plating | Electro-chemical process where layer of copper is deposited on metallic surface by electric current. |
| Ionic contamination | Ionic residue that interfere with reliability and functionality. |
| Laminates | Contains inner prepreg like a copper-clad laminate. |
| Prepreg | Base material reinforced with resin or polyimide that is partially cured. |
| Multilayer pressing | use of high temperature and high pressure to make the semi-cured sheet heat melt, and make it flow, and then transformed into a cured sheet. |
| Controlled impedance | Regulation of resistance exerted by signal traces. |
| HDI | High density interconnects PCBs have tracks and/or vias with a width or diameter of under 152 micrometers. |
| FR-2 | Phenolic paper or phenolic cotton paper, paper impregnated with a phenol formaldehyde resin. |
| FR-4 | Woven fiberglass cloth impregnated with an epoxy resin. Low water absorption (up to about 0.15%), good insulation properties, good arc resistance. |
| Aluminum board | Metal core board or insulated metal substrate (IMS), clad with thermally conductive thin dielectric - used for parts requiring significant cooling. |
| Flexible substrates | Standalone copper-clad foil; can also be laminated to a thin stiffener. |
| Polyimide | Polyimide is a flexible material and is used for flex and rigid/flex boards, while FR4 is for rigid PCBs. |
| Electrical resistance | Measure of opposition circuit gives to flow of electric current. |
| Ground plane | Electrically conductive surface, usually connected to electrical ground; acts as the return path for most components and current in the circuit. |
| Transmission line | Connects moving signals from their transmitters to their receivers on PCB. |
| Relative permittivity | Dielectric constant (Dk) measures capacitance between pair of conductors in a laminate and that pair of conductors in a vacuum. |
| Dissipation factor | Loss tangent (Df) measures signal attenuation as signal propagates down transmission line. |
| Ball grid array | Surface mount chip package that uses a grid of solder balls as its connectors. |
| Tg | Glass transition temperature of polymer is temp at which material changes from a relatively stiff, "glassy" state to a more pliable or softened state. |
| Propagation delay | One-way time required by a signal to travel on a particular PCB trace. |
| Capacitor | Device used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator. |
| Via fill | Via hole completely filled; hole closed with conductive or non-conductive epoxy material or copper plating. |
| Solder mask | Thin coating of polymer required to protect board from any uncertain short circuits and maintaining the integrity of the copper traces. |
| Pre-baking | Pre-treatment to dry boards and moisture-sensitive components before assembly to remove moisture from inside or on surface. |
| Peel strength | Bond strength between the copper conductor and the dielectric material. |
| HATS | Highly accelerated thermal shock; air-to-air thermal cycling procedure that quickly heats and cools test vehicles at min/max temperatures. |
| IST | Interconnect stress testing; electrical charge to heat the coupon and stress the vias. |
| Fine lines / spaces | Boards with 2-5 mil line and spacing. |
| Heatsink | PCBs that ensure cooling by absorbing and dissipating heat from electronic components. |
| Resin Starvation | Voids; area with insufficient resin needed to completely wet out reinforcement. |
| Td | Decomposition Temperature is the temperature at which a PCB material chemically decomposes. |
