Metal Etching Engineering Drawing: Five Design Guidelines and Application Strategies for Connection Points

In precision metal etching (photo chemical etching), the design of connection points (Tabs) is paramount in the engineering drawing stage. These tiny contact points connecting the product to the edge material not only determine the success or failure of production but also directly affect the visual aesthetics and functional realization of the finished product.

During etching, the metal plate needs to withstand the high-pressure spray from the upper and lower nozzles. When the chemical solution penetrates the metal, if there are no connection points to hold the product and edge material together, the parts will fall directly into the etching tank, resulting in scrap or equipment damage.

Design Principles:

• Positive Correlation: The larger the workpiece, the thicker the material, and the higher the etching difficulty, the larger the connection points should be.
• Variable Considerations: The size of the connection points must comprehensively balance three major factors: workpiece size, material type, and thickness.

Based on product appearance requirements and functional uses, connection points in drafting can be divided into the following five independent categories:

Design Logic: The connection point is located outside the outer contour of the part.

Characteristics: A small protrusion will remain on the outer circumference of the product after disassembly.

Applicable Scenarios: Workpieces requiring the integrity of the product's shape and where gaps are not allowed (such as mobile phone cases, surface decorative parts). The protrusion can be removed by grinding later.

Design Logic: The connection position is recessed inwards from the part.

Characteristics: After disassembly, the burr is recessed at the edge of the product and does not affect the overall dimensions.

Empirical Data: When the material thickness is below 0.2mm, it is recommended to set the recess width to 0.5mm and the depth to 0.15mm.

Applicable Scenarios: Industrial functional products; currently the most cost-effective and widely used solution.

Design Logic: The connection structure is retained only when half the depth of the material's front side is etched away.

Features: After removing the product, no obvious protrusions or notches are visible on the front; the notch is hidden on the back.

Applicable Scenarios: Widely used in signage, logos, and other components where strict visual requirements apply to the front.

Design Logic: The connection point is located on the back half-etched section, the opposite of the front half-etched design.

Features: Ensures a clean back surface; suitable for precision parts requiring a flat mounting surface.

Thickness Recommendation: When the material thickness is > 0.3mm, a half-etched design is often used to reduce disassembly difficulty and grinding workload.

Design Logic: The product is completely separated from the edge material; no physical connection points are provided.

Process Costs: Single-sided etching requires applying an adhesive film to one side, followed by tedious processes such as casting and ink removal, resulting in low yield and significantly increased costs.

Limitations: Generally not recommended for products thicker than 0.2mm, unless the customer has extremely demanding aesthetic requirements.

Setting connection points is not only a technical indicator but also an "art of trade-offs." Excellent drafting engineers will find the optimal solution between production stability, finished product aesthetics, and subsequent processing costs based on the specific application scenario of the product.