Laminated Contact Foils with Differential Softening Points
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Solution Overview
Problem
Existing pressure contact devices for laminated bodies, such as chip cards, are complex and expensive to produce, often requiring precise alignment and multiple insert elements, and lack reliability against manipulation due to the use of hot lamination which can fill cavities between contact elements.
Innovation Solution
A pressure contact device is developed using a simplified method where a spacer is dispensed with, allowing hot lamination to connect layers without filling the cavity, with contact elements and a central layer forming the cavity walls, and using materials with higher softening points to prevent manipulation, while maintaining a cost-effective and reliable production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hot lamination is used to connect film layers, then the connection strength and resistance to manipulation is improved, but the cavity between contact elements may be filled by softened material
Solution Approach 1:
The patent applies parameter changes by selecting materials with different softening points - the intermediate foil has a lower softening point than the contact foils. During hot lamination, the intermediate foil softens and bonds to contact foils, while the contact foils remain rigid and prevent cavity filling. This differential parameter approach resolves the contradiction between achieving strong bonds and preventing harmful material flow.
Solution Approach 2:
The patent uses composite materials with different thermal properties - combining a low-softening-point intermediate foil with high-softening-point contact foils. This composite structure enables selective softening during hot lamination, allowing the intermediate layer to bond while the contact elements maintain their shape and prevent cavity formation.
2Object-generated harmful factors
If cold bonding is used to connect film layers, then the cavity filling problem is avoided, but the connection strength and resistance to manipulation is reduced
Solution Approach 1:
The patent changes the thermal parameter of the intermediate foil by selecting a material with lower softening point than the contact foils. This enables hot lamination to be applied selectively - the intermediate foil softens and bonds strongly to contact foils, while the contact foils remain rigid. This resolves the contradiction by enabling thermal bonding without the harmful effects of cold bonding's weak connection.
3Reliability
If multiple insert elements (two contact elements and one spacer) are used for each switching element, then the electrical contact function is improved, but the production complexity and cost increases
Solution Approach 1:
The patent extracts and eliminates the spacer component from the traditional three-element assembly. Instead of using a separate spacer to maintain the cavity, the intermediate foil itself serves as the cavity-defining layer through its lower softening point material. This extraction simplifies production by reducing the number of insert elements from three to two, while maintaining the electrical contact function through the differential material properties.
Solution Approach 2:
The intermediate foil serves multiple functions simultaneously: it acts as a bonding layer during hot lamination, defines the cavity shape, and prevents material flow into the cavity. By giving the intermediate foil these multiple functions, the patent eliminates the need for separate spacer and bonding layers, reducing complexity while maintaining functionality.
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 enables the production of a reliable and cost-effective pressure contact device for laminated bodies, ensuring secure electrical contacts and protection against manipulation, while simplifying the manufacturing process and reducing production costs.
Implementation Method 1
By exerting pressure on at least one of the two contact foils in the area of the perforation of the intermediate foil, the contact foil is deformed and electrical contact is established between the two contact foils. If no more pressure is exerted, the contact foil returns to its original shape due to its elasticity.
Implementation Method 2
Connecting the film layers by hot lamination has the advantage over cold bonding that the film layers soften during hot lamination and are inseparably connected to one another.
Implementation Method 3
each switching element in the stack of layers is formed using a material that has a higher softening temperature than the film material in such a way that within the switching element a through this material against the surrounding film material delimited cavity is formed
Data Source
Figure 1~3
Figure 3a~3c
Figure 4~5
AI summary
The device has a central layer (30) arranged between contact layers (10, 20), and comprising a recess in a region of contact elements, where the recess forms a hollow space. The space is limited by the central layer, and the recess comprises smaller dimension in an extension direction of a laminated body (1) as a contact insert (12). Dimensions of the recess in extension direction of the body are smaller than dimensions of another contact insert, and material of the central layer has a lower softening temperature than material of the contact elements. An independent claim is also included for a device for manufacturing a pressure contact device.