PCB Thermal Transfer Printing for Sharp, Solder-Resistant Tracks
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Solution Overview
Problem
Existing methods for manufacturing printed circuit boards with electrically conductive tracks on nonconductive substrates are time-consuming and do not ensure optimal edge sharpness and structural integrity, especially when soldering electronic components.
Innovation Solution
A method and device that use a thermal printer with a print head that selectively heats a two-dimensional layer of electrically conductive material on a carrier foil, transferring it onto a nonconductive substrate by melting or sintering, ensuring precise pattern transfer without direct contact between the print head and the printing medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching is used to remove copper after transferring conductor tracks, then conductor tracks can be formed on copper-coated substrate, but the process is time-consuming and proceeds at limited speed
Solution Approach 1:
The patent replaces the mechanical/chemical etching process with a thermal printing process. A print head selectively heats and transfers conductor track material onto the substrate, eliminating the multi-step etching process while achieving precise conductor track formation and significantly increasing manufacturing speed
Solution Approach 2:
The patent uses a print head to selectively transfer conductor track material from a source onto the substrate in the desired pattern, similar to printing. This copying approach directly forms the conductor tracks without requiring prior copper coating and etching, thereby simplifying the process and improving productivity
2Reliability
If soldering temperature is kept slightly above melting temperature of soldering tin, then electronic components are protected from overheating, but the temperature is insufficient to heat metals for conductor tracks to their required melting temperature
Solution Approach 1:
The print head applies heat locally and selectively to specific areas where conductor tracks are needed, rather than heating the entire substrate uniformly. This localized heating allows the conductor track material to reach its required melting temperature while the rest of the substrate and electronic components remain at safe temperatures
Solution Approach 2:
The print head operates by applying periodic thermal pulses to melt and transfer the conductor track material. This periodic heating action allows precise control over the temperature and duration of heating, ensuring the conductor material reaches the necessary temperature while protecting other components
3Productivity
If a print head directly contacts the printing medium, then transfer efficiency may improve, but the print head becomes contaminated and requires frequent cleaning or replacement
Solution Approach 1:
The patent introduces a carrier foil as an intermediary between the print head and the printing medium. The print head heats the printing medium on the carrier foil, which then transfers to the substrate. The carrier foil protects the print head from direct contact with the printing material, preventing contamination while maintaining efficient thermal transfer
Solution Approach 2:
The patent uses a thin flexible carrier foil to carry the printing medium. This thin film allows efficient thermal conduction from the print head to the printing material while acting as a protective barrier that prevents the print head from contacting and becoming contaminated by the conductor track material
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 allows for rapid and efficient production of printed circuit boards with conductor tracks of uniform thickness and sharp edges, capable of withstanding soldering temperatures without melting, thus ensuring structural integrity.
Implementation Method 1
a print head for selective, localized heating of individual print spots or pixels of an electrically conductive printing medium
Implementation Method 2
so that the printing medium is transferred to, i.e., imprinted on, the electrically nonconductive substrate by selective melting or sintering of the material for the electrically conductive tracks
Implementation Method 3
so that the printing medium is transferred to, i.e., imprinted on, the electrically nonconductive substrate by selective melting or sintering of the material for the electrically conductive tracks
Implementation Method 4
at least in a section of the carrier film which is actually in the area of the print head, the side of the carrier film bearing the printing medium is always oriented parallel to the substrate and rests flatly against the substrate, so that the metal or metal alloy is in direct contact with the substrate
Data Source
AI summary
A method for manufacturing printed circuit boards for electrical and electronic circuits, comprising an electrically nonconductive substrate (4) and electrically conductive tracks applied thereon, wherein the electrically conductive tracks are imprinted on the substrate (4), according to a desired conductor track layout, under the influence of heat applied to an electrically conductive printing medium (3), wherein the printing medium (3) comprises an electrically conductive metal or metal alloy having a melting temperature, and wherein the metal or metal alloy is configured to be selectively heated by a print head (2) at selected printing spots or pixels, wherein a conductive ingredient of the metal or metal alloy of the printing medium (3) is locally heated at least up to the melting temperature of the metal or the metal alloy, which is the melting point of the metal or metal alloy in the form of a bulk material and is melted thereby, and thereafter solidifys on the substrate (4) in the form of a common matrix, and wherein the printing medium (3) is situated on a side of-a film-like carrier (6), which side of the film-like carrier (6) faces the substrate (4), characterized in that the film-like carrier (6) is a carbon foil or a glass film, and is wound from a supply spool (7), along the substrate (4) to be imprinted, onto a laydown spool (8), and wherein, at least in a section of the carrier film (6) which is actually in the area of the print head (2), the side of the carrier film (6) bearing the printing medium (3) is always oriented parallel to the substrate (4) and rests flatly against the substrate (4), so that the metal or metal alloy is in direct contact with the substrate (4), and, after being melted by the print head (2) into its fluid aggregate state, the metal or metal alloy immediately moistens the substrate (4) and finally solidifies on the substrate (4) as a common matrix.