THT vs SMT vs THR

Introduction

Selecting the right RJ45 connector mounting method is a critical decision in network hardware design. From industrial automation to consumer electronics, the way an RJ45 connector is attached to a PCB directly affects electrical performance, mechanical reliability, and manufacturing efficiency. The three most common approaches—Through-Hole Technology (THT), Surface-Mount Technology (SMT), and Through-Hole Reflow (THR)—each serve specific engineering goals. In this guide, we break down these methods in detail and introduce real-world examples from LINK-PP, a leading RJ45 connector manufacturer.

Quick Comparison

Feature

THT

SMT

THR

PCB Hole Required

✅ Yes

❌ No

✅ Yes

Soldering Method

Wave Soldering

Reflow Soldering

Reflow Soldering

Mechanical Strength

⭐⭐⭐⭐⭐

⭐⭐

⭐⭐⭐⭐

Automation Compatibility

⭐⭐

⭐⭐⭐⭐⭐

⭐⭐⭐⭐

Space Efficiency

⭐⭐

⭐⭐⭐⭐⭐

⭐⭐⭐

Best Use Case

Industrial/Heavy Duty

Compact Consumer Devices

Hybrid/Automated Industry

Ethernet Speed Support

Up to 10Gbps+

Up to 10Gbps

Up to 10Gbps+

Cost

Moderate

Low

Moderate

Mounting Methods

1. THT (Through-Hole Technology)

Through-Hole RJ45 Connector

Overview

THT involves inserting connector pins into drilled holes on the PCB, with solder joints formed on the opposite side—typically using wave soldering. This traditional technique offers strong mechanical retention and has long been the standard in industrial and high-reliability environments.

Advantages

  • Superior mechanical strength for environments with vibration or stress

  • Ideal for heavier or magnetics-integrated RJ45 connectors

  • Proven long-term durability

Limitations

  • Requires drilling plated holes, increasing PCB manufacturing cost

  • Takes up more board space, limiting use in dense layouts

Common Applications

  • Industrial switches

  • Power over Ethernet (PoE) devices

  • Legacy routers and network hubs

LINK-PP THT RJ45 Examples

📌 Model: LPJ0188CNL
A shielded RJ45 connector with integrated magnetics, optimized for 10/100Base-T applications.
🔍 Download datasheet

2. SMT (Surface-Mount Technology)

SMT RJ45 connectors

Overview

SMT RJ45 connectors are soldered directly onto the surface of the PCB using reflow soldering, eliminating the need for hole drilling. This makes them ideal for automated production and compact electronic designs.

Advantages

  • Space-saving for high-density layouts

  • Lower cost due to reduced PCB drilling

  • High-speed automated assembly compatible

Limitations

  • Weaker mechanical stability under physical stress

  • Less suited for environments requiring frequent plugging/unplugging

Common Applications

  • Home routers and set-top boxes

  • Embedded Ethernet modules

  • Compact consumer devices

LINK-PP SMT RJ45 Example

📌 Model: LPJ19325AHNL
A compact Surface-Mount RJ45 Jacks, designed for Digital Camera and Router.
🔍 Download datasheet

3. THR (Through-Hole Reflow)

THR RJ45

Overview

THR combines the mechanical benefits of THT with the automation compatibility of SMT. The connector’s leads pass through holes in the PCB and are soldered via reflow, not wave soldering. This hybrid approach simplifies production without sacrificing strength.

Advantages

  • High mechanical strength similar to THT

  • Streamlined with SMT reflow processes

  • Compatible with double-sided reflow assembly

Limitations

  • Requires heat-resistant materials

  • Slightly more complex PCB pad and stencil design

Common Applications

  • Automotive Ethernet systems

  • High-reliability embedded systems

  • Industrial IoT devices

LINK-PP THR RJ45 Example

📌 Model: LPJG0926HENLS4R
An advanced THR RJ45 with integrated magnetics, shielded body, and enhanced EMI protection—ideal for PoE+ and gigabit Ethernet systems.
🔍 Download datasheet

📘 How to Choose the Right Mounting Method for RJ45 Connectors

Selecting the best mounting style isn’t just about preference — it depends on the application’s mechanical, electrical, and manufacturing requirements. Below are some practical guidelines:

★ Prioritize Mechanical Strength?

Use THT for robust industrial deployments, especially in environments prone to vibration or mechanical stress.

★ Need Compact, High-Density PCB Layout?

Go with SMT RJ45 connectors. They are surface-mountable and compatible with automated reflow soldering processes.

★ Looking for Reflow Compatibility + Mechanical Strength?

THR offers the best of both worlds. It enables reflow soldering while maintaining the mechanical stability of through-hole components — LPJG0926HENLS4R is a reliable option.

★ Design for Automated Assembly?

Both SMT and THR connectors are compatible with automated pick-and-place and reflow lines, reducing labor cost and improving consistency.

★ Cost vs. Reliability Trade-Off?

  • THT may increase cost due to drilling but enhances durability.

  • SMT is cost-effective for large-scale, compact designs.

  • THR balances both, especially where wave soldering is not feasible.

🔎 Also See

Enhance your understanding of PCB mounting and soldering technologies with these related resources from LINK-PP: