Lead Frame Encapsulation Without Molds
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Solution Overview
Problem
Existing methods for encasing stamped grids connected to mechanical, electrical, or electronic components are costly and unsuitable for small quantities, as they require expensive molds and can cause component stress due to high temperatures during plastic injection molding.
Innovation Solution
Applying an electrically conductive connecting compound to the stamped grids, followed by a protective plastic coating at lower temperatures, eliminating the need for molds and reducing component stress, while allowing the conductive connections to form permanently during the heating process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional injection molding with molds is used to encase stamped grids, then manufacturing precision and reliability are improved, but device complexity and production costs increase significantly
Solution Approach 1:
The invention extracts and eliminates the mold from the encapsulation process. Instead of using complex injection molds, the patent applies liquid plastic material directly to the stamped grid using simple application tools, allowing the grid to be encapsulated without requiring sophisticated forming equipment.
Solution Approach 2:
The invention replaces expensive, complex molds with simple, disposable application methods. The liquid plastic material is applied directly without reusable tooling, reducing equipment investment and making the process suitable for small production quantities.
2Manufacturing precision
If conventional injection molding with molds is used to encase stamped grids, then manufacturing precision is improved, but production costs increase significantly
Solution Approach 1:
The mold is extracted from the process entirely, eliminating the high costs associated with mold design, manufacturing, and maintenance. The patent uses direct application of liquid plastic material, which requires minimal equipment investment.
Solution Approach 2:
The invention uses inexpensive, non-reusable application methods instead of expensive reusable molds. This approach is particularly cost-effective for small production runs where mold costs would be prohibitively high.
3Manufacturing precision
If high temperature plastic material is used in injection molding, then encasing quality is improved, but component stress and functional failure risk increase
Solution Approach 1:
The invention changes the temperature parameter of the plastic material from high temperature (conventional injection molding) to low temperature (liquid state). This allows the material to remain liquid during application and only harden after contacting the component, avoiding thermal stress on sensitive components.
Solution Approach 2:
The component is positioned and prepared before the plastic material is applied. The liquid plastic is then applied around the already-positioned component, allowing the component to be protected from thermal exposure while still achieving proper encapsulation.
4Manufacturing precision
If conventional injection molding is used for small quantities, then encasing quality is maintained, but productivity and economic efficiency decrease
Solution Approach 1:
The mold is removed from the process, eliminating the setup time and complexity associated with loading and unloading parts from molds. This direct application method is more efficient for small production quantities.
Solution Approach 2:
The invention uses simple, non-reusable application methods that are cost-effective and efficient for small production runs, eliminating the economies-of-scale requirement that makes mold-based injection molding viable only for large quantities.
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 method reduces costs, minimizes component stress, and enables efficient encapsulation and connection of components in small quantities without the need for complex tools, enhancing process reliability and allowing for the production of complex circuits.
Implementation Method 1
the plastic material is applied, e.g. by screen printing, stencil printing, dispensing, preferably jet dispensing, or by immersing the stamped grid equipped with the components in the liquid plastic material
Implementation Method 2
the plastic material is applied, e.g. by screen printing, stencil printing, dispensing, preferably jet dispensing, or by immersing the stamped grid equipped with the components in the liquid plastic material
Implementation Method 3
the plastic material is applied, e.g. by screen printing, stencil printing, dispensing, preferably jet dispensing, or by immersing the stamped grid equipped with the components in the liquid plastic material
Implementation Method 4
waiting until the liquid plastic material has hardened
Implementation Method 5
This entire assembly is subjected to heating (e.g. in an oven) so that the components involved are heated to the required temperature. It is essential that this required temperature is below the temperatures that are required in conventional plastic injection molding processes with molds, and that it assumes a value at which the electrically conductive connecting mass is melted to form the connection points
Implementation Method 6
the electrically conductive connecting mass is melted to form the connection points of the component with the connection points to be permanently connected to each other on the stamped grid
Implementation Method 7
If a conductive adhesive is used as the electrically conductive connecting compound, there is the additional advantage that its curing takes place at the same time as the enveloping plastic material is cured
Data Source
Figure 1a~1e
Figure 2~3b
AI summary
The invention relates to a method for encasing several die-cut grids that are connected to mechanical, electrical, or electronic components, wherein the die-cut grids are surrounded by a casing made of a plastic material, wherein according to the invention it is provided that the casing is applied around the die-cut grids without a forming tool.