Light-Emitting Module Paste Compression for Thin Reliable Connections
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Solution Overview
Problem
Conventional methods for reducing the thickness and resistance of electrically conductive paste in light-emitting modules are limited, as they primarily focus on thermal compression of adhesive materials within through holes or on the board, without effectively addressing the resistance of the conductive paste in the connection structure.
Innovation Solution
A method involving a board with circuit patterns and bottomed holes, where electrically conductive paste is supplied through a mask and subjected to thermal compression, resulting in hardened paste with reduced thickness and improved connection reliability, and an insulating resin is applied to cover the paste, enhancing the module's electrical conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional method using a screen is used to supply electrically conductive paste, then the paste can be supplied uniformly, but it is difficult to supply paste with different thicknesses in different regions and the edges of the paste are rough
Solution Approach 1:
A mask with openings is introduced as an intermediary tool to control paste supply. The mask enables precise thickness control in different regions by varying opening sizes and positions, while also smoothing paste edges through the defined opening geometry, replacing the conventional screen method
Solution Approach 2:
The mask is designed with openings of different sizes and shapes at different locations to supply paste with specific thicknesses to different regions. This allows each region to receive paste with locally optimized thickness and edge smoothness according to its specific requirements
2Strength
If the bonding surface of the light-emitting device is made large to ensure bonding strength, then bonding reliability improves, but the light-emitting module cannot be thinned
Solution Approach 1:
The electrical conductive paste is subjected to thermal compression to change its physical parameters, transforming it from a thick, soft state to a thin, hardened state. This parameter change allows the paste to provide sufficient bonding strength while reducing thickness to enable module thinning
3Reliability
If electrically conductive paste is supplied thick to ensure conductivity and bonding, then electrical connection is reliable, but the module thickness increases and productivity decreases
Solution Approach 1:
The paste is supplied with sufficient thickness initially to ensure complete fill of bottomed holes and adequate material for bonding, then thermal compression is applied to reduce thickness. This preliminary action ensures reliability while enabling subsequent thinning for productivity
Solution Approach 2:
The paste undergoes a phase transition from a soft, compressible state during supply to a hardened, dimensionally stable state after thermal compression. This phase transition allows thickness reduction while maintaining electrical conductivity and bonding reliability
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 approach reduces the resistance and thickness of the electrically conductive paste, leading to improved connection reliability and stability in light-emitting modules, facilitating efficient electrical conductivity and minimizing uneven resistance.
Implementation Method 1
a step of performing thermal compression to harden the electrically conductive paste such that the thickness of the electrically conductive paste on the portions of the surface of the wiring pad is smaller than the electrically conductive paste at the timing of being disposed through the openings of the mask
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
A method for manufacturing a light-emitting module includes a step of providing a bonded board including a board including, on a first surface, a circuit pattern and wiring pads that are continuous with the circuit pattern and each have bottomed holes and light-emitting segments connected on a second surface of the board with an adhesive sheet interposed therebetween and including an array of light-emitting devices; a step of supplying electrically conductive paste inside the bottomed holes and on portions of the surface of the wiring pad around the bottomed holes through openings of a mask; and a step of performing thermal compression to harden the electrically conductive paste such that the thickness of the electrically conductive paste on the portions of the surface of the wiring pad is smaller than the electrically conductive paste at the timing of being disposed through the openings of the mask.