Silver-Coated Nickel Wire for Film Resistor Soldering
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Solution Overview
Problem
The existing methods for mass production of film resistors are costly and complex, particularly in high-temperature applications, due to the difficulty in simplifying the soldering process while maintaining the protective properties of platinum sheaths and avoiding intermetallic phase formation that degrades the resistor's quality.
Innovation Solution
The use of silver-coated nickel wires with a thin silver sheath allows for soft solder attachment, where the silver sheath is significantly thinner than the nickel core, and a glass or ceramic coating is applied to enhance the connection strength and prevent intermetallic phase formation, enabling bubble-free strain relief and easy separation of resistors by breaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a platinum sheath is used to protect the connecting wire, then the protective properties are maintained, but the soldering process becomes difficult and complex
Solution Approach 1:
The connecting wire uses a composite structure with a nickel core and a silver sheath. The silver sheath enables easy soldering with soft solder while the nickel core provides mechanical strength. This composite material approach resolves the contradiction by combining materials with complementary properties - silver for solderability and nickel for structural integrity.
Solution Approach 2:
The silver sheath is designed to be thin (0.2 to 20 μm, preferably 1 to 5 μm) compared to the nickel core diameter (100 to 400 μm). This thin protective layer provides sufficient solderability without requiring a thick, difficult-to-solder platinum coating, simplifying the manufacturing process while maintaining functionality.
2Ease of manufacture
If a thick silver sheath is used to enable soft solder attachment, then soldering is simplified, but intermetallic phase formation degrades the resistor quality
Solution Approach 1:
The silver sheath thickness is precisely controlled to be significantly thinner than the nickel core diameter (at least one order of magnitude thinner, preferably two orders of magnitude). This parameter optimization allows soft solder attachment while minimizing intermetallic phase formation that would degrade resistor quality, resolving the contradiction between ease of manufacture and manufacturing precision.
3Productivity
If multiple layer resistors are glazed together on a common substrate, then productivity increases, but separation becomes complex requiring sawing
Solution Approach 1:
The glass paste is applied with predetermined breaking points that allow the glazed resistors to be easily separated by breaking apart rather than requiring complex sawing processes. This segmentation approach enables mass production of multiple resistors on a common substrate while simplifying the separation process through pre-defined fracture lines.
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 simplifies the production of high-quality film resistors by preventing intermetallic phase formation, maintaining electrical conductivity, and allowing for simultaneous production of multiple resistors on a substrate, which can be easily separated, reducing production costs and complexity.
Implementation Method 1
the sheath and the core remain as separate phases when the sheathed wire is connected to the pad of the sheet resistor blank
Implementation Method 2
a glass or ceramic coating is applied to enhance the connection strength and prevent intermetallic phase formation
Implementation Method 3
The glass paste is sintered into a porous body
Implementation Method 4
the wire is heated in such a way that a glass layer is formed around the heated wire
Data Source
AI summary
The resistor has a platinum measuring resistor made of an electrically insulated substrate, and a connecting wire i.e. casing wire (1), connected with the measuring resistor. The connecting wire comprises a coated nickel body (2), and a silver casing (3) consists of silver or mixture of silver with glass or ceramics. The silver casing or a silver phase or the nickel body comprises a purity of 99 gram equivalent weight percentages. The nickel body comprises a diameter of 100-400 micrometers, and the silver casing has a thickness of 0.2-5 micrometer. Independent claims are also included for the following: (1) a method for manufacturing a film resistor (2) a method for connecting a film resistor with a wire made of nickel basis.