PCB VIA (Vertical Interconnect Access)

VIA, short for Vertical Interconnect Access, is a crucial element in multi-layer printed circuit boards (PCBs). These copper-plated holes allow electrical and thermal connections between layers, supporting compact, high-performance electronic devices.

What Is a VIA?

A via is a small hole drilled (mechanically or by laser) through PCB layers, filled or plated with copper, enabling electrical continuity between layers. It consists of:

• Barrel: The conductive tube lining the hole.

• Pad: The copper ring that connects the via to a trace.

• Anti-pad: The clearance around the via to isolate it from non-connected copper layers.

🔧 How Are Vias Made

1. Copper pads are placed on each layer.

2. Holes are drilled through the stack at connection points.

3. Der epoxy resin is removed chemically, exposing copper pads.

4. The barrel is formed by electroplating copper inside the hole.

5. Lötmaske is applied to protect and isolate.

✔️ This process allows engineers to stack multiple layers efficiently, minimizing board size while maximizing circuit complexity.

🔍 Types of Vias

1️⃣ Through-Hole Vias

Fully penetrates the PCB from top to bottom.

Advantages:

• Strong mechanical and electrical connection

• Good thermal conductivity

• Easy for inspection and rework

• Supports through-hole components

Limitations:

• Consumes space on all layers

• Larger drill sizes limit layout density

• May introduce signal reflections at high frequencies

Use Cases: Power/ground connections, connector mounting, thermal transfer.

2️⃣ Blind Vias

Connects outer layer to one or more inner layers, but doesn’t go through the entire board.

Benefits:

• Increases routing density

• Shorter electrical paths = better high-frequency performance

• Saves board space

• Reduces total layer count in complex designs

Anwendungen:
Mobile devices, high-speed circuits, tragbare Elektronik, aerospace systems.

3️⃣ Buried Vias

Completely enclosed inside the board—connects inner layers only, invisible from the outside.

Manufacturing Challenges:

• Requires sequential lamination and drilling

• Needs precise alignment

• Harder to inspect (requires X-ray)

Advantages:

• Excellent signal integrity

• Lower EMI emissions

• Frees up surface area

• Greater routing flexibility

Anwendungen: High-speed designs, RF boards, compact multilayer PCBs

Choosing the Right Via

Why Vias Matter in Modern PCBs

Vias support:

📡 Signal routing across layers

🔌 Power distribution and grounding

🌡️ Thermal management

🧩 High-density interconnects (HDI)

🎯 Precision performance in compact electronics

Zusammenfassung

Vias are core elements in multi-layer PCB design. They impact everything from performance and size to manufacturing cost and signal integrity. Selecting the right via type is crucial for your product’s success in today’s fast-evolving electronics landscape.