Chip Card Contact Pad Rotation Control
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Solution Overview
Problem
The manufacturing of microcircuit card supports is delicate, particularly during cavity machining, where metal pads are exposed, leading to potential false contacts and short circuits due to tool-induced pad rotation.
Innovation Solution
A microcircuit card support with metallic contact pads, where the first part is anchored to prevent rotation in a predefined direction, ensuring the second part remains stationary, even when exposed during machining, using a T-shaped pad design with lateral extensions to block rotation in specific directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cavity is machined to expose the metal pads for electrical connection, then the electrical connection between antenna and microcircuit is enabled, but the machining tool can cause rotation of the pads leading to false contacts and short circuits
Solution Approach 1:
The pad is designed with an asymmetric shape including a lateral extension that protrudes into the mass of material before machining. This preliminary geometric configuration prevents rotation during the cavity machining process by providing a mechanical stop that blocks rotational movement, ensuring the pad remains in its correct position throughout manufacturing
Solution Approach 2:
The pad features an asymmetric geometry with a lateral extension on one side but not the other. This asymmetry creates a predefined direction of rotation that is blocked by the extension coming into abutment with the mass of material, thereby preventing unintended rotational displacement during machining operations
2Strength
If the pad is fully embedded in the mass of material, then the pad is protected during machining, but the electrical connection to the microcircuit cannot be established
Solution Approach 1:
The pad is divided into two distinct parts: a first part embedded in the mass of material that provides stability and prevents rotation during machining, and a second part that is exposed to enable electrical connection. This segmentation allows each part to fulfill its specific function without compromising the other
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The support (12) has a body formed in a material mass, and metallic contact stubs incorporated in the body. The contact stubs respectively include a set of parts (48A, 48B) drowned in the material mass, and another set of parts (50A, 50B) exposed. The former set of parts respectively block rotation of the contact stubs around an axis (X) orthogonal to the support in two opposite rotation directions (S1, S2). The contact stubs are extended in the same plane of the support. The body is formed by lamination of a pile of layers, and an antenna is incorporated in the body. An independent claim is also included for a chip card comprising a microcircuit.