PTC Thermistor Component with Sputtered Barrier and Dipped Cap
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Solution Overview
Problem
Existing PTC components face challenges in minimizing tolerance errors related to electrical properties, and there is a need for an effective method to produce such components with precise electrical characteristics.
Innovation Solution
A PTC component with a base made of PTC ceramics, featuring a first conductive layer as a barrier layer on the end faces and a second conductive layer forming a cap that covers the edges, using a combination of materials like chromium, nickel, and silver, applied through sputtering, dipping, and screen printing processes, along with a method involving substrate preparation, metallization, and cap application to ensure low manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional production methods are used for PTC components, then manufacturing simplicity is maintained, but tolerance errors in electrical properties increase
Solution Approach 1:
The conductive layer is divided into two distinct layers: a first conductive layer that contacts the base body end face, and a second conductive layer that forms a cap covering the end face across the edges. This segmentation allows each layer to be optimized for its specific function, improving electrical property control while managing production complexity through specialized deposition processes for each layer
Solution Approach 2:
Different regions of the conductive structure are assigned different materials and properties: the first conductive layer uses materials optimized for adhesion to the base body, while the second conductive layer uses materials optimized for electrical conductivity and cap formation. This local differentiation of material properties enables precise control over electrical characteristics at different locations, reducing tolerance errors
2Reliability
If the second conductive layer covers the end face across edges, then electrical connection reliability is improved, but geometric dimension control becomes more difficult
Solution Approach 1:
The second conductive layer transitions from a two-dimensional planar contact to a three-dimensional cap structure that covers the end face across the edges. This dimensional change ensures reliable electrical connection by maintaining contact even with geometric variations, while the cap geometry provides tolerance compensation for dimensional variations in the base body
3Manufacturing precision
If multiple partial layers with different materials are used, then adhesion and electrical properties are improved, but manufacturing process complexity increases
Solution Approach 1:
The first conductive layer is constructed as a composite structure with a chromium-containing sub-layer for adhesion to the base body and a nickel-containing sub-layer for enhanced electrical conductivity and corrosion resistance. This composite material approach optimizes both adhesion strength and electrical properties while the standardized deposition processes keep manufacturing complexity manageable
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 results in PTC components with minimized tolerance errors and improved electrical properties, enabling precise electrical characteristics and surface mountability, while maintaining low geometric dimensions and manufacturing tolerances.
Implementation Method 1
The bottom sub-layer of the first conductive layer is preferably sputtered on
Implementation Method 2
a nickel-containing sub-layer is preferably applied... The Cr layer can e.g. B. be generated in a thickness of 0.1 to 1.0 microns. Thereafter, a nickel-containing layer z. B. with a thickness of 0.1 to 1.0 microns preferably applied by sputtering and reinforced galvanically
Implementation Method 3
The second conductive layer preferably has at least one layer applied by a dipping process, e.g. B. a silver-containing layer
Implementation Method 4
The second conductive layer can e.g. B. have a silver-containing lower part-layer, a nickel-containing middle part-layer and a solderable, in particular tin-containing, upper part-layer
Data Source
AI summary
Disclosed is an electrical positive temperature coefficient (PTC) thermistor component comprising a base (1), a first conductive layer, and a second conductive layer which are disposed on the front sides of the base (1), respectively. The surface area of the base (1) is free from the first conductive layer while the second conductive layer forms caps (31, 32) which are respectively arranged at the front end of the base (1). Also disclosed is a method for producing said PTC thermistor component. The first conductive layer (21, 22) is produced on main surfaces of a substrate (10) by means of sputtering before component sections are separated. The cap-shaped second conductive layer is produced on front sides of a separate component section in a dipping process.