Latest Advances in PCB Technologies

With the introduction of new semi-additive technologies, trace widths in printed circuit boards (PCBs) can now be reduced to as low as 1.25 mils, allowing for increased circuit assembly density.
The industry’s most commonly used subtractive PCB process offers a minimum wiring design tolerance of 0.5 mil, impacting impedance control in thinner wiring designs.
PCB manufacturing initially involves covering one or both sides with a copper-containing substrate material known as the core, leading to variations in insulation and mechanical properties.

Subtractive vs. Semi-Additive Methods

When comparing the subtractive and semi-additive methods in PCB manufacturing:

The subtractive method involves etching copper in an acid bath to create a wiring design, while the semi-additive method laminates a substrate with a thin copper foil and utilizes photolithography for wiring design.
Precise impedance control is crucial for high-speed digital systems and microwave applications, with the semi-additive method offering advantages in achieving near-vertical wiring designs.

Key points regarding impedance control and circuit assembly density in PCB manufacturing:

Attaining a rectangular wiring design enhances predictability in impedance, leading to improved circuit assembly density and manufacturing yield.
The semi-additive method allows for maintaining a wiring design width of 1.25 mils with controlled impedance, benefiting high-speed digital systems and microwave applications.