What Are the Electrical Properties of Fast Turn Circuit Board Manufacturing?

Electrical Properties of Fast Turn Circuit Board Manufacturing

A quick-turn PCB can be a cost effective solution for those in need of a short-run prototype or a few small production runs. However, it is important that the PCB be of high quality in order to avoid a lot of problems down the road. This can be achieved by rigorously checking the design for manufacturability. This is done during the prototyping stage and can be a valuable time saver in preventing re-work in later stages of production.

The electrical properties of a fast turn circuit board manufacturing can be determined by the materials used and the fabrication techniques employed. These factors can determine a number of critical parameters such as conductor loss, dielectric constant, and the track profile. These factors affect the performance of the circuit board and must be considered when selecting a material for a project.

Printed circuit boards (PCBs) consist of a substrate and copper-clad laminate that is attached to it. The substrate is usually a dielectric composite that includes a polymer resin (dielectric) with fillers and reinforcements. The most common is epoxy, but other types of resins such as BT, PPE, cyanate ester and modified acrylates are also used. The reinforcement can be a fiberglass-impregnated paper, woven or nonwoven glass fibers, cotton, or metal. The copper foil is then bonded to the dielectric with either a hot or cold roll lamination process.

What Are the Electrical Properties of Fast Turn Circuit Board Manufacturing?

The thickness of the copper clad layers and their surface finish are important factors in electrical conductivity. A smoother surface will increase conductivity and decrease impedance, while a rougher surface will reduce conductivity and increase impedance. The electrical properties of the copper can be further enhanced by applying an oxidation or a thermal spray coating.

A good insulator must have a low dielectric constant, ideally less than 1. A lower dielectric constant will allow signals to propagate at higher frequencies, while a higher dielectric constant can cause reflections and phase distortion in wideband applications. The dielectric breakdown voltage and tracking resistance are also important properties of a PCB dielectric.

The PCB manufacturing process starts with a customer sending a PCB design to a manufacturer in Gerber file format. The manufacturer performs a Design for Manufacturability review on the design and verifies technical and material specifications. They then send the final design to the factory for fabrication. The factory uses additive or subtractive methods to create the PCB.

In additive processes a bare laminate is covered with a photosensitive mask which is exposed to light in a pattern that exposes and sensitizes areas of the design to be plated with copper. This creates conductive holes called plated-through holes which connect the layers of a multilayer circuit board together. After the plating, a variety of finishes are applied to the copper, including organic solderability preservative (OSP), immersion silver (IAg), immersion tin (ISn), and electroless nickel immersion gold (ENIG).