UV LED Lithography Exposure Device for PCB Pattern Transfer
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Solution Overview
Problem
Conventional lithography exposure devices for printed circuit boards are costly and inefficient due to the use of expensive lasers and inefficient light sources like fluorescent tubes, which waste energy by emitting light across a broader spectrum, including visible light that the photoresist is not sensitive to.
Innovation Solution
A lithography exposure device using UV light-emitting diodes (UV LEDs) with optical means to focus and control the light, allowing for precise exposure of patterns directly onto the substrate through relative movement in two dimensions, reducing the half-value angle of the light and concentrating it into a small exposure spot, thereby optimizing energy use and reducing material waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If fluorescent tubes are used for exposure, then the photoresist can be exposed, but a high proportion of emitted light is in the visible range to which the photoresist is not sensitive, resulting in inefficient energy use
Solution Approach 1:
The patent changes the spectral parameters of the light source from broad-spectrum fluorescent tubes to UV-LEDs that emit specifically in the 350-450nm range. This parameter change ensures that the emitted light matches the sensitivity characteristics of the photoresist, eliminating waste of energy in the visible spectrum while maintaining sufficient UV intensity for effective exposure.
2Manufacturing precision
If lasers are used for direct exposure, then precise pattern transfer is achieved, but the cost of the exposure device becomes very high
Solution Approach 1:
The patent replaces expensive lasers with relatively inexpensive UV-LEDs as the light source. While individual UV-LEDs have shorter lifetimes compared to lasers, their low cost allows for economical replacement. This substitution dramatically reduces the overall device cost while maintaining adequate exposure precision through proper optical design and movement control.
Solution Approach 2:
The patent uses a movement device to scan the UV-LED light source across the substrate, creating patterns through relative motion. This copying approach—where a single light source position is replicated across the entire substrate area through systematic movement—achieves the same pattern transfer function as multi-point laser arrays but at much lower cost.
3Productivity
If multiple lasers are used to provide sufficient intensity, then rapid exposure is enabled, but the costs remain at a high level
Solution Approach 1:
The patent employs a movement device that enables continuous scanning of the UV-LED light source across the substrate during exposure. This continuous motion allows the single light source to cover the entire substrate area without interruption, achieving high productivity equivalent to multiple simultaneous light sources but at the cost of a single, economical UV-LED combined with precise motion control.
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 solution provides a cost-effective, energy-efficient, and precise method for exposing patterns on printed circuit boards, enabling the production of high-resolution conductor tracks with reduced material usage and lower operational costs, while eliminating the need for additional mask materials.
Implementation Method 1
an exposure device having a UV light-emitting light-emitting diode (UV-LED)
Implementation Method 2
The exposure changes the nature of the resist in such a way that the exposed and unexposed structures can be released differently from a developer liquid
Implementation Method 3
optical means which control the radiation or Reduce the half-value angle α' of the emitted light step by step and finally bundle or focus it on the substrate in an exposure spot
Data Source
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AI summary
The invention relates to a lithographic exposure device 42 with an exposure unit 10 for exposing a substrate 20 with a photosensitive layer. The lithographic exposure device comprises a movement device for generating relative movement between the exposure unit 10 and the substrate 20 during exposure, wherein the exposure unit 10 has at least one UV light-emitting diode 2.