Haba Weld

Definition

A precision thermocompression bonding process that applies simultaneous heat and pressure via a heated hot bar to melt solder or cure conductive adhesive, reliably connecting flexible printed circuits (FPCs) and ribbon cables to PCBs or components.

A precision thermal compression bonding process that uses a heated Hot Bar to apply temperature and pressure to the weld zone, melting solder or curing conductive adhesive to reliably connect FPCs and flex cables to PCBs or components.

Alias

Detailed explanation

Hot Bar welding (Hot Bar) is a pulsed thermocompression bonding technique widely used in electronics manufacturing for fine-pitch applications such as FPC-to-PCB, FPC-to-FFC, and LCD module flex cable connections. The core principle involves a weld head (typically made of titanium alloy or tungsten carbide) that rapidly heats up via an internal heating element. As the head presses down, it transfers heat to the joint, instantly melting solder paste, ACF (Anisotropic Conductive Film), or SMD solder pre-applied to the area. The assembly then cools and solidifies under pressure during the hold phase. The complete process consists of 5 stages: Preheat → Ramp-up → Hold at Peak Temperature → Pressure Hold & Cool → Head Lift-off. The entire cycle typically completes within 5–15 seconds, with peak temperatures ranging from 180–450℃ depending on the solder type. Hot Bar welding demands extreme temperature precision: too low a temperature results in cold joints or open circuits, while excessive heat can damage the FPC coverlay or the chip itself. Consequently, strict control over temperature accuracy (recommended ±1℃) and response time (recommended < 0.5s) is essential. K-type armored thermocouples are commonly placed close to the weld head for measurement, paired with PID closed-loop temperature control.

Typical Value

{"Welding Temperature": "180–450°C", "Welding Pressure": "5–50 N", "Soak Time": "2–10 s", "Heating Rate": "50–200°C/s", "Temperature Control Accuracy": "±1°C max", "Ultrasonic Horn Material": "Titanium Alloy / Tungsten Carbide / Molybdenum Alloy"}

Unit

°C (welding temperature) / N (welding pressure) / s (holding time)