SMD LED Positioning on PCB Using Adhesive Bonding
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Solution Overview
Problem
The existing methods for mounting SMD semiconductor light sources in motor vehicle headlights result in undesirably large positional inaccuracies due to blurring and tilting in the liquid solder, which affects the photometric requirements for light distribution.
Innovation Solution
Applying adhesive to predetermined points on the printed circuit board or the SMD semiconductor light source before positioning, and bonding it to the board before melting the solder, thereby preventing unwanted changes in position during the soldering process, using a handling system with camera and image-processing control for precise alignment relative to defined reference marks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is applied and melted to attach the SMD semiconductor light source to the circuit board, then electrical and mechanical connection is achieved, but positional inaccuracies increase due to blurring and tilting in the liquid solder
Solution Approach 1:
Adhesive is applied to predetermined locations on the circuit board and/or SMD semiconductor light source before the soldering step, and the SMD semiconductor light source is bonded to the circuit board in the desired position before the solder is melted. This preliminary bonding action prevents positional changes during the subsequent solder melting process, thereby maintaining positioning accuracy while achieving reliable connection.
2Manufacturing precision
If the SMD semiconductor light source is positioned precisely on the circuit board, then photometric requirements are met, but positional tolerances increase during the soldering process due to buoyancy forces in liquid solder
Solution Approach 1:
The SMD semiconductor light source is bonded to the circuit board using adhesive before the solder is melted, establishing a stable position that prevents blurring and tilting caused by buoyancy forces in the liquid solder during the soldering process.
Solution Approach 2:
Adhesive is introduced as an intermediary substance between the SMD semiconductor light source and the circuit board, providing temporary mechanical support and position stability during the soldering process before the solder solidifies.
3Manufacturing precision
If adhesive is applied and bonding is performed before solder melting, then positional inaccuracies are reduced, but process complexity increases
Solution Approach 1:
The adhesive bonding step and soldering step are merged into a single integrated process where both operations are performed in sequence without removing the workpiece from the fixture, thereby reducing handling complexity despite adding a bonding step.
Solution Approach 2:
The process utilizes temperature parameter changes during soldering to control the state of materials (adhesive curing and solder melting) in a controlled sequence, enabling the multi-step process to be executed automatically without manual intervention.
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 significantly reduces positional inaccuracies, improves compliance with photometric requirements, and decreases the reject rate during manufacturing, leading to more efficient and accurate headlight production.
Implementation Method 1
adhesive is applied to predetermined locations on the circuit board and/or the SMD semiconductor light source before the solder is melted, and the SMD semiconductor light source is bonded to the circuit board in the position achieved by the positioning step
Implementation Method 2
an adhesive that cures by ultraviolet radiation is used, which is irradiated with ultraviolet light before the solder is melted
Implementation Method 3
a solder joint is created by temporarily melting the solder in a soldering oven and then allowing it to cool
Implementation Method 4
at least one camera and an image processing control of a handling system that grips and positions the SMD semiconductor light source
Data Source
Figure 1~3
Figure 4
Figure 5a
AI summary
A method for attaching a semiconductor light source (12) to a printed circuit board (10) of a motor vehicle headlight is presented, comprising the following steps: applying solder (54) to predetermined locations on the printed circuit board and/or at predetermined locations on the SMD semiconductor light source; positioning the SMD semiconductor light source on the printed circuit board in a position where a solder joint is subsequently made; and temporarily melting the solder in a soldering oven and cooling the solder. The method is characterized by the fact that, prior to melting the solder, adhesive (104, 106) is applied to predetermined locations on the printed circuit board and/or the SMD semiconductor light source, and that the SMD semiconductor light source is bonded to the printed circuit board in the position achieved by the positioning step.