Homogenized Area Laser Soldering: A Constant-Temperature Heat Pressing Approach for FPC Applications

May 26, 2025

As microelectronics packaging evolves from board-level to system-level integration, demand for high-performance flexible interconnects continues to grow. Flexible Flat Cables (FFC) and Flexible Printed Circuits (FPC) are increasingly used in mobile devices, PCBA-to-PCBA interconnects, and high-speed data transmission in consumer electronics and automotive applications. However, traditional soldering techniques often fall short when it comes to meeting the precision and thermal sensitivity requirements of these components.

To address these challenges, Han’s Laser introduces a state-of-the-art solution: Laser Constant-Temperature Heat Press Soldering using Homogenized Area Light Technology—a non-contact, high-precision soldering process engineered specifically for fine-pitch FPC connections.

How It Works

Unlike traditional thermocompression bonding, which requires physical contact with the solder pads, laser heat press soldering delivers energy without touching the surface. This is critical when working with fine-pitch FPCs, where even minor mechanical stress or thermal deviation can lead to defects.

Constant-Temperature Laser Hot Pressing Process Flow

The homogenized area light laser welding system heats only the targeted soldering region, leaving the surrounding board material unaffected. By expanding the laser spot into a controllable rectangular area, the system ensures even energy distribution—making simultaneous multi-point soldering both possible and efficient.

A dedicated pressing jig ensures steady and uniform pressure throughout the process. Combined with a coaxial temperature monitoring system, the equipment delivers accurate thermal feedback to keep temperature fluctuations within ±5°C, significantly reducing the risk of FPC warping, delamination, or component damage.

Real-World Application

Joint Structure: PCBA + FPC

Soldering Method: Constant-Temperature Laser Heat Press

Cycle Time: 6 seconds per unit

Number of Pads: 51

Pad Diameter: 0.5 mm

FPC Aperture: 0.2 mm

Welding Case

This method delivers consistent solder joint quality, reduced cycle times, and minimal thermal stress—ideal for high-density, high-precision interconnects.

Welding result

System Overview

The homogenized area light laser soldering machine integrates a motion platform, laser source, industrial control PC, and proprietary beam-shaping optics. Optional visual positioning cameras enable high-accuracy alignment.

Key features include

Customizable Spot Size: From 2.5×2.5 mm up to 17×17 mm, adapting to various solder pad layouts.
Dual Workstations: Supports simultaneous feeding and soldering to maximize throughput.
Real-Time Focus and Temperature Control: Ensures precise heating and optimal joint formation.
Multi-Format Solder Supply: Compatible with paste, wire, or preform solder sources.

Application Areas

This laser soldering solution is well-suited for:

Automotive electronics (infotainment systems, ADAS modules)
Consumer electronics (smartphones, wearables, tablets)
Home appliances (smart displays, touch panels)
Communication devices (5G modules, RF boards)

Process Advantages

Simultaneous Multi-Point Soldering

Achieve consistent results with one-time energy discharge across multiple pads—ideal for dense FPC designs.

Adjustable Beam Size

Supports flexible pad layouts and reduces soldering cycle times across a variety of products.

Precision Temperature Control

Maintain optimal solder joint temperatures between 50°C and 800°C, with ±5°C accuracy.

Modular Integration

Available as standalone modules or complete workstations to suit different production environments.

Future-Proofing Electronics Manufacturing

As devices grow thinner, faster, and more interconnected, FFC and FPC interconnect solutions play a vital role. In consumer electronics, demand for lightweight and multifunctional designs continues to rise. FPCs meet the stringent requirements of next-gen smartphones and wearables.

In automotive electronics, the shift toward electric and intelligent vehicles increases the need for compact, high-speed interconnects. FPCs help optimize space and simplify harness structures while improving signal transmission efficiency.

Emerging technologies like IoT and AI also depend on high-density connections. Laser heat press soldering—especially with homogenized area light—ensures reliable, scalable, and damage-free joining that meets the demands of the future.