Thermocompression Bond Head with Movable Cooling Heat Sink

Solution Overview

Problem

Thermocompression bonding machines face challenges in rapidly switching between heating and cooling phases, affecting machine throughput due to serial temperature ramp up and ramp down processes, which are slow and inefficient.

Innovation Solution

A bond head assembly with a cooling heat sink that is mechanically separated during heating and brought into contact during cooling, combined with a flexure system for precise positioning and differential expansion, and a chamber that can switch between different fluids or positions to manage heat transfer effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the bonding tool is heated rapidly for efficient bonding, then the bonding speed is improved, but the heat loss during cooling phase increases and reduces machine throughput

Engineering Contradiction:

Improvebonding speedVSAvoidheat loss during cooling

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The cooling heat sink is designed to be movable rather than fixed, allowing it to dynamically change position between contacting and non-contacting states with the bonding tool. This dynamic configuration enables the system to minimize heat loss during heating by separating the heat sink, while maximizing heat removal during cooling by bringing the heat sink into contact.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The cooling heat sink is pre-positioned in a non-contacting state during the heating phase, preparing the system to rapidly transition to cooling mode. The flexure system pre-positions the heat sink such that it can quickly make contact with the bonding tool when cooling is required, reducing the transition time and maximizing throughput.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If a fixed cooling heat sink is used, then the structure is simple, but the heating and cooling phases cannot be rapidly switched affecting throughput

Engineering Contradiction:

Improvestructure simplicityVSAvoidmachine throughput

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The cooling heat sink is designed to be movable rather than fixed, allowing it to dynamically change position between contacting and non-contacting states with the bonding tool. This dynamic configuration enables the system to minimize heat loss during heating by separating the heat sink, while maximizing heat removal during cooling by bringing the heat sink into contact.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The flexure system utilizes differential thermal expansion characteristics to accommodate the bonding tool's expansion during heating while maintaining the heat sink's ability to contact the tool during cooling. The flexure materials are selected to have appropriate thermal expansion coefficients that allow for rapid thermal cycling without compromising structural integrity or contact reliability.

Inventive Principle:

Principle #37Thermal expansion

3Temperature

If the cooling heat sink contacts the bonding tool continuously, then cooling is maximized, but heat loss during heating increases and bonding precision deteriorates

Engineering Contradiction:

Improvecooling efficiencyVSAvoidworkpiece placement precision

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The cooling heat sink is designed to be movable rather than fixed, allowing it to dynamically change position between contacting and non-contacting states with the bonding tool. This dynamic configuration enables the system to minimize heat loss during heating by separating the heat sink, while maximizing heat removal during cooling by bringing the heat sink into contact.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The flexure system acts as an intermediary mechanism between the cooling heat sink and the bonding tool, providing controlled compliance and positioning. The flexure allows the heat sink to approach and contact the bonding tool with precise control, accommodating thermal expansion differences while maintaining adequate contact pressure for effective heat transfer during cooling phases.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration allows for rapid heating and cooling of the bonding tool, increasing the speed of the bonding process and improving machine throughput by minimizing heat loss during heating and maximizing heat loss during cooling, while maintaining precise workpiece placement.

Implementation Method 1

a heater configured to heat the workpiece to be bonded

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a chamber proximate the heater, the chamber configured to receive a cooling fluid for cooling the heater

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 3

at least two flexures disposed between the support structure and the heater

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS9847314B2Bond heads for thermocompression bonders, thermocompression bonders, and methods of operating the same

Publication Date: 2017.12.19 KULICKE & SOFFA IND INC

AI summary

A bond head for a thermocompression bonder is provided. The bond head includes a tool configured to hold a workpiece to be bonded, a heater configured to heat the workpiece to be bonded, and a chamber proximate the heater. The chamber is configured to receive a cooling fluid for cooling the heater.