Molex Micro-Fit First Mate, Last Break Terminals

Introduction

Molex Micro-Fit First Mate, Last Break (FMLB) terminals are specialized connector terminals designed to improve safety and reliability during power connection and disconnection. Their sequencing design ensures that the ground connection is established before power contacts engage and remains connected after power contacts separate.

Part Description

Micro-Fit FMLB terminals are part of Molex’s compact Micro-Fit connector ecosystem, which uses a 3.00 mm pitch. The defining feature of these terminals is a longer ground pin that provides built-in mechanical sequencing.

During mating, the longer ground terminal connects first, followed by the power and signal terminals. During unmating, the power and signal terminals disconnect first while the ground contact remains connected until last. This first-mate, last-break behavior helps reduce the risk of electrical arcing, accidental grounding issues, and connection damage.

Key characteristics include:

• First-mate, last-break ground-contact sequencing
• Longer ground pin for mechanical sequencing
• Up to 10.5 A current capability
• Maximum voltage rating of 600 V
• 3.00 mm connector pitch
• Compact Micro-Fit form factor
• Designed for arc-free and damage-resistant power connections
• Suitable for applications requiring controlled power connection sequencing

Applications

Potential applications for Molex Micro-Fit FMLB terminals include:

• Hot-pluggable power modules
• Battery pack connections
• DC power distribution systems
• Industrial control equipment
• Motor controllers and drives
• Power supplies
• Robotics assemblies
• Server and networking equipment
• Medical electronic equipment
• Test and measurement instruments
• Charging systems
• Portable and rugged electronic devices

Industries

These terminals can be used across a range of industries, including:

• Industrial automation
• Robotics
• Automotive and transportation
• Energy storage
• Renewable energy
• Telecommunications
• Data centers
• Medical devices
• Consumer electronics
• Aerospace and defense equipment
• Laboratory and test equipment
• Building and facility automation

Usage Ideas

1. Sequenced Battery Connector
   Build a removable battery interface for a mobile robot, using the FMLB ground terminal to establish a ground path before battery power is applied.

2. Modular DC Power Supply
   Design a rack-mounted DC power module with a Micro-Fit FMLB connection to reduce arcing and improve safety when modules are inserted or removed.

3. Industrial Sensor Hub
   Create an industrial sensor distribution enclosure where detachable power harnesses use first-mate, last-break terminals for more reliable field servicing.

Conclusion

Molex Micro-Fit First Mate, Last Break terminals provide a compact solution for applications that need controlled connection sequencing. By mating ground first and disconnecting it last, they help support safer power handling, reduce arcing risk, and protect connectors during repeated mating cycles. With up to 10.5 A current capability, 600 V maximum voltage, and a 3.00 mm pitch, they are well suited to compact industrial, power, automation, and modular electronic systems.