Optically Selective Joint Structure for Uniform Thermal Adhesion
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Solution Overview
Problem
Existing photonic soldering methods risk damaging electronic components and wiring substrates due to non-uniform melting of thermal adhesive materials and excessive heating, which is exacerbated by varying heat conductivity based on component size.
Innovation Solution
A joint structure is designed with specific absorption coefficients for light wavelengths, allowing light pulses to transmit through base materials while generating heat only in the joint portion, ensuring uniform heat distribution and using a thermal adhesive material with a low melting point to facilitate joining without excessive heat exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the output of the light pulse is increased to uniformly melt the thermal adhesive material, then the uniformity of melting is improved, but the electronic component is heated to a temperature higher than the damage temperature and is damaged
Solution Approach 1:
The patent applies local quality by designing the joint portion with specific light absorption properties (absorption coefficient of 2×10^5 cm^-1 or more) that differ from the base materials. This localized optical property ensures that light energy is selectively absorbed and converted to heat only in the joint portion, enabling uniform melting of the thermal adhesive material without overheating the electronic component base material.
Solution Approach 2:
The joint portion acts as an intermediary that mediates between the light pulse and the thermal adhesive material. By positioning the joint portion (including electrodes and thermal adhesive material) as an intermediate layer with high light absorption, the system achieves controlled heating of the adhesive without directly heating the electronic component, thus resolving the contradiction between uniform melting and component damage.
2Manufacturing precision
If heat conductivity differs depending on the size of the electronic component, then the thermal adhesive material is not uniformly melted, but increasing light pulse output to uniformly melt the material causes excessive heating and damage
Solution Approach 1:
The patent resolves this contradiction by applying local quality through spatial differentiation of optical absorption properties. The joint portion is specifically engineered with high light absorption (absorption coefficient of 2×10^5 cm^-1 or more) while base materials have low absorption (1.5×10^5 cm^-1 or less). This localized optical property ensures that regardless of electronic component size, the light energy is concentrated in the joint portion, achieving uniform adhesive melting without excessive heating of the component.
3Strength
If a light pulse of high energy is generated for thermal adhesion, then the adhesion strength is improved, but the electronic component and wiring substrate are damaged or degraded
Solution Approach 1:
The patent applies local quality by creating a spatial distinction in light absorption between the joint portion and base materials. The joint portion contains materials with high absorption coefficients (2×10^5 cm^-1 or more) that convert light energy to heat efficiently, generating sufficient thermal energy for strong adhesion. Meanwhile, base materials have low absorption coefficients (1.5×10^5 cm^-1 or less), protecting them from damage while still achieving high adhesion strength.
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
The joint structure improves joinability between electronic components and wiring substrates while minimizing damage, allowing for efficient and uniform bonding without cracking or degradation.
Implementation Method 1
the joint portion includes a material having an absorption coefficient of 2×10^5 cm−1 or more for light of a wavelength of 250 to 1000 nm
Implementation Method 2
heat is conducted to a thermal adhesive material joint portion
Implementation Method 3
the base material of at least one component of the electronic component and the wiring substrate consists of a material having an absorption coefficient of 1.5×10^5 cm−1 or less for the light of a wavelength of 250 to 1000 nm
Data Source
AI summary
A joint structure, in which an electronic component and a wiring substrate are joined to each other, includes: a base material of the electronic component; a base material of the wiring substrate; and a joint portion that includes at least an electrode of the electronic component and an electrode of the wiring substrate, and that joins the base material of the electronic component and the base material of the wiring substrate. The joint portion includes a material having an absorption coefficient of 2×10{circumflex over ( )}5 cm−1 or more for light of a wavelength of 250 to 1000 nm. The base material of at least one component of the electronic component and the wiring substrate consists of a material having an absorption coefficient of 1.5×10{circumflex over ( )}5 cm−1 or less for the light of a wavelength of 250 to 1000 nm.