Thermocompression Bonding of Circuit Members Using Solder Adhesive
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Solution Overview
Problem
Existing methods for connecting circuit members using anisotropic conductive adhesives face challenges such as high pressure and thermal stress, leading to defects and inefficient capture of conductive particles, especially in thin and low-strength circuit members with narrow electrode pitches.
Innovation Solution
A thermocompression bonding method involving a connection material with a solder material, where the solder is pressed at a first pressure before reaching its melting point and then at a lower second pressure, allowing it to be melted and spread between electrodes, reducing the need for high pressure and minimizing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high pressure is applied to the anisotropic conductive adhesive to achieve electric connection, then the conductive particle can be compressed into contact with the electrode, but the viscosity of the adhesive deteriorates and fluidity increases, causing the conductive particle to be pushed out to the periphery
Solution Approach 1:
The patent changes the physical state parameter of the solder material from solid to liquid by controlling temperature, enabling the solder to flow and fill gaps between electrodes without requiring high pressure, thus preventing particle ejection while ensuring reliable electrical connection
Solution Approach 2:
The patent utilizes the phase transition of solder material from solid to liquid state during heating to achieve automatic filling and wetting of electrode surfaces, eliminating the need for high-pressure compression and preventing conductive particle ejection to periphery
2Reliability
If high pressure is applied during thermocompression bonding, then electric connection can be achieved, but thermal stress applied to the circuit member increases, causing defects such as curve in thin and low-strength circuit members
Solution Approach 1:
The patent changes the connection mechanism from mechanical compression requiring high pressure to thermal phase transition of solder, significantly reducing the pressure and thermal stress applied to thin circuit members while ensuring reliable electrical connection
Solution Approach 2:
The patent replaces the mechanical compression system with a thermal phase transition system, where heat induces solder melting and flow to achieve connection, substituting mechanical force with thermal energy to protect thin circuit members from damage
3Reliability
If the adhesive is heated to melt the solder particle, then electric connection is achieved, but the adhesive fluidity increases and the solder particle is pushed out from the part between the electrodes
Solution Approach 1:
The patent applies pressure to the solder particle before heating to pre-position it between the electrodes, then melts the solder to enable it to fill gaps and wet electrode surfaces without being pushed out, achieving both reliable connection and precise positioning
Solution Approach 2:
The patent implements a two-stage process: first applying pressure to position the solder, then heating to melt and flow the solder, separating the positioning and connection actions in sequence to prevent solder ejection while ensuring reliable electrical connection
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 method enhances the reliability of electric connections by firmly capturing the solder between electrodes, reducing the risk of short circuits and defects, particularly in thin or low-strength circuit members with narrow electrode pitches.
Implementation Method 1
after a time t13, main heating is performed at a temperature T12 that exceeds the melting point Tm. In the main heating, when the solder particle is melted
Implementation Method 2
when the solder particle is melted and wet-spreads to the electrode
Data Source
AI summary
A connecting method of a circuit member, includes: a first process of preparing a connection material that a solder material disperses in the adhesive; a second process of disposing the first circuit member and the second circuit member to cause the first electrode of the first circuit member and the second electrode of the second circuit member to oppose each other via the connection material; and a third process of compressing the first circuit member and the second circuit member while applying heat to the connection material. The third process includes a first pressing process which is performed before a temperature of the connection material reaches a melting point of the solder material, and a second pressing process which follows the first pressing process.