Collagen Peptides as Leveling and Grain-Refining Additives in PCB Copper Plating

As demand grows for high-density printed circuit boards (HDI PCBs), advanced semiconductor packaging, and automotive electronics, copper electroplating processes used in PCB fabrication require extremely tight control. Collagen-derived peptides are used as bio-based additives in acidic copper plating baths to regulate copper deposition behavior, improving surface smoothness, grain uniformity, and mechanical reliability of plated copper layers.

The Role of Copper Plating in PCB and Semiconductor Manufacturing

Copper electroplating is a critical step in PCB fabrication and semiconductor interconnect formation. It is used to build conductive traces, vias, and interconnect layers that electrically connect semiconductor devices and electronic components.

Key applications include:

PCB Manufacturing:
Copper plating forms signal traces, through-hole vias, and microvias in multilayer and HDI PCBs, where surface uniformity directly impacts signal integrity and reliability.

Semiconductor Packaging:
In advanced semiconductor substrates and interposers, copper electroplating enables fine-line interconnections between chips and packages, requiring precise grain control and low defect density.

How Collagen Functions as a Plating Additive

In acidic copper sulfate electroplating systems used for PCB and semiconductor applications, collagen peptides act as organic adsorption modifiers and leveling agents.

Their function is based on controlled adsorption at the cathode surface:

Selective Adsorption Control:
Collagen peptides preferentially adsorb onto high-current density areas of the copper surface, temporarily suppressing copper ion (Cu²⁺) reduction in those regions.

Surface Leveling Effect:
By moderating deposition at surface peaks, copper growth is redirected toward low-current density areas, resulting in a smoother, more uniform plated surface.

Grain Refinement:
The macromolecular structure of collagen peptides influences nucleation behavior, promoting fine and evenly distributed copper grains rather than coarse or columnar growth.

Mechanical Reliability Support:
Compared to aggressive synthetic additives, collagen peptides help maintain balanced tensile strength and ductility, reducing the risk of cracking during thermal cycling or mechanical stress.