They say that a community shows definite signs of growth when it undergoes a lot of construction. This may be because new construction means an individual or family is ascending or that new jobs are being created, or both. Regardless of the underlying source, the sight of a foundation usually means good tidings or some sort.
In Part 3 of this series, we broadly introduced circuit board manufacturing by way of defining some of the most important terminologies that you should know. This prepares us to delve deeper into the PCB construction process and build upon our database by adding the most pertinent PCB fabrication terminology.
List of PCB Fabrication Terminology
A bare board is a printed circuit board (PCB) that reflects your layout, but without components. Typically, the first stop for your PCB manufacturing files is the fab or board house. Here, the materials for your PCB stackup are bound together through pressing and adhesion into the bare board.
A PCB core is a dielectric material with copper plating on both sides. The base refers to a dielectric board that comprises the core of the PCB stackup, which varies in material properties depending upon the number of layers, insulation or dielectric properties desired, and types of signals that propagate on and through the board.
Board house refers to a factory that builds or fabricates bare boards or PCBs.
Fabrication is the stage of PCB development that is comprised of a series of PCB manufacturing steps that begin with imaging the layout and ends with the application of a metal-based (typically gold) surface finish to protect the bare board until the assembly when the components are soldered on.
FR-4, which stands for “flame retardant” grade 4 or woven glass-reinforced epoxy resin is a core material that usually has copper on both sides and is a good general-purpose material that works great for many board applications. This may come as a bit of a surprise, but FR-4 is not the only PCB material available for your board design. There are alternatives that should be explored for special board types, such as when high-speed and high-temperature PCBAs are required.
High density interconnect (HDI)
High density interconnect (HDI) technology utilizes small densely packed traces to maximize board area. It may seem paradoxical, but as electronics products get smaller and smaller they are called upon to have more functionality, which often translates into high-speed PCBs. HDI is one of the most successful ways of meeting this demand.
Laminate, which is often confused with prepreg, is fully cured core material with copper attached. Prepreg is typically an uncured core. Although not limited to the PCB industry, ambiguity among terms certainly exists when discussing materials used in board fabrication. A common pair that meets this criterion is prepreg and laminate. A source of this confusion probably lies in the fact that both are used as PCB insulation between layers.
Non-plated through hole (NPTH)
Non-plated through holes (NPTHs) are non-copper plated PCB drill holes used to mount or install boards in enclosures or other devices.
Plated through hole (PTH)
The other type of PCB drill hole is the plated through hole or PTH, which is primarily used to carry current vertically through the board. These vias are also used to aid in heat dissipation. The PCB copper plating process implemented to fill the via depends upon its intended usage.
Solder mask is applied everywhere on the board surfaces, except copper areas where components are soldered, and provide clearance that prevents solder bridges. PCBAs are quite resilient, and if well-made, will last for many, many years. Of course, that can only occur if PCBAs are protected, which is the first responsibility of the solder mask process.
As most contemporary circuit boards are small and complex, knowing how multilayer PCBs are made can be leveraged to improve the design of the stackup, which is the vertical arrangement of layers, materials, and vias of your board. For best results, a 3D perspective of your board’s architecture is necessary.
The PCB substrate, which is sometimes used interchangeably with laminate and core, is a base material that defines the board’s structural integrity and other material properties.
Incorporating the PCB fabrication terminology that is defined above into our growing database should provide greater insight into why DFM, which is bounded by material properties and equipment capabilities, is important.
|Tempo's Custom PCB Manufacturing Service
At Tempo Automation, to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.
Congratulations on adding the terms in this blog to your PCB terminology database. Now, let’s build on these by adding PCB Assembly Terminology You Should Know.
To access the complete PCB Terminology series and expand your PCB knowledge, please refer to the following articles:
Part 1: PCB Terminology You Should Know
Part 2: PCB Design Terminology You Should Know
Part 3: PCB Manufacturing Terminology You Should Know
Part 4: PCB Fabrication Terminology You Should Know
Part 5: PCB Assembly Terminology You Should Know