Light-emitting Module Positioning via Adhesive Curing
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Solution Overview
Problem
The displacement of Surface Mount Technology (SMT) elements, such as LEDs, during the reflow soldering process due to tolerances and alignment issues, results in positioning inaccuracies exceeding ±100 um, posing a challenge in the development of precise light-emitting modules for vehicle lamps.
Innovation Solution
A light-emitting module design featuring a circuit board with a conductive layer and an adhesive material with a curing temperature lower than the melting point of the conductive layer, positioned at the periphery of the device-attachment area, which contacts the light-emitting device's lateral and bottom sides, ensuring precise positioning and minimizing displacement during reflow soldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If SMT reflow soldering process is used to mount LEDs on substrate, then electrical connection and mass production are achieved, but positioning precision deteriorates with offset exceeding ±100 um
Solution Approach 1:
The adhesive material is applied to the substrate before mounting the LED, creating a preliminary bonding that prevents displacement during the reflow soldering process. This preliminary action ensures the LED remains at the predetermined position while still allowing for mass production through automated application processes.
Solution Approach 2:
The adhesive material acts as an intermediary substance between the LED and the substrate, providing a bonding interface that maintains positioning precision. The adhesive fills the gap between the LED and substrate, preventing direct thermal contact that would cause displacement while enabling electrical connection through the conductive layer.
2Strength
If adhesive material completely surrounds the light-emitting device, then bonding strength is improved, but light emission is blocked
Solution Approach 1:
The adhesive material is applied selectively at specific locations (lateral and bottom sides) rather than completely surrounding the LED. This localized application provides sufficient bonding strength at the mounting interface while leaving the top emitting surface completely clear for optimal light emission.
Solution Approach 2:
Instead of applying adhesive uniformly around the entire perimeter, the adhesive is applied partially only where needed for bonding (lateral and bottom sides). This partial action achieves the necessary bonding strength without the excessive action of complete surrounding, which would block light.
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 design achieves precise positioning of SMT elements with an offset less than ±25 um, enhancing the reliability and accuracy of light-emitting modules for vehicle lamps by stabilizing the light-emitting device relative to the circuit board.
Implementation Method 1
an adhesive material having at least one point structure... for connecting the light-emitting device to the circuit board
Implementation Method 2
a conductive layer disposed on the device-attachment area... electrically connected to the circuit board through the conductive layer
Implementation Method 3
a curing temperature of the adhesive material is lower than a melting point of the conductive layer
Data Source
AI summary
Disclosed is a light-emitting module, comprising: a circuit board, a conductive layer, a light-emitting device, and an adhesive material. The circuit board comprises a device-attachment area, the conductive layer being disposed on the device-attachment area, the light-emitting device being disposed on the conductive layer and electrically connected to the circuit board through the conductive layer, and the adhesive layer being used for connecting the light-emitting device to the circuit board, wherein a curing temperature of the adhesive layer is lower than a melting point of the conductive layer. Adopting the aforementioned technical means, the degree of offset in the position of the light-emitting device after reflow soldering can be greatly reduced. In addition, a vehicle lamp device using the light-emitting module is also provided.