System on Module (SoM) Connection Methods: Castellated Pad vs. Edge Connector

When designing embedded systems, selecting the right method to connect a System on Module(SoM) to a carrier board is essential. The two most common approaches are castellated pads and edge connectors. Each offers unique benefits depending on your project's design goals.

1. Castellated Pad (Soldered) Connection

Castellated pads are semi-plated, surface-mount pads located around the edges of a SoM. These are designed to be permanently soldered to the baseboard using SMT reflow soldering.

Key Benefits:

• Compact and rugged—ideal for industrial environments

• Lower cost in high-volume production

• Provides strong mechanical and electrical connection

2. Edge Connector (Pluggable) Connection

Edge connectors use gold-plated contact fingers that insert into a socket on the baseboard. This modular approach allows for easy replacement or upgrade of the SoM.

Key Benefits:

• Hot-swappable and easy to service

• Faster development turnaround for prototypes

• Supports high-speed signal integrity

Comparison Table

Which One Should You Choose?

If your application demands durability and low unit cost in large volumes, castellated pads may be ideal. If you prioritize flexibility and ease of maintenance, an edge connector is likely the better choice.

Looking for RK3399 SoMs with either interface? View our product lineup here.

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