Insert-Molded Lead Frame with Pre-Formed Notches
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Solution Overview
Problem
Existing methods for manufacturing insert-molded articles expose the cut planes of tie bars to the external resin, leading to insulation issues, decreased air-tightness, and oxidation degradation.
Innovation Solution
A method and apparatus that allow resin molding and tie bar cutting in a single process by using low-strength portions at the tie bar boundaries, which are easily broken by tie bar cutting punches, ensuring the cut planes are buried within the resin, and utilizing pilot pins and holding means for precise positioning and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If tie bars are cut after resin molding, then resin molding can be performed normally, but the cut planes of tie bars are exposed to outside causing insulation issues and oxidation
Solution Approach 1:
The patent applies preliminary action by pre-forming notches at specific positions on the tie bars before resin molding. These notches are positioned so that when the tie bars are subsequently cut, the cut planes are located inside the resin interface rather than exposed to the outside. This preliminary positioning of cut locations ensures that the cutting operation naturally results in buried cut planes, eliminating insulation issues and oxidation exposure while maintaining normal resin molding functionality.
2Productivity
If tie bar cutting is integrated into the forming mold, then working hours and equipment cost decrease, but the cut planes become exposed to outside
Solution Approach 1:
The patent incorporates preliminary action by pre-forming notches on the tie bars at positions that will become the cut locations after molding. This preliminary preparation allows the integrating mold to cut the tie bars at the correct positions without exposing the cut planes to the outside environment, thus achieving both productivity improvement and reliability maintenance.
Solution Approach 2:
The patent applies local quality by creating notches at specific localized positions on the tie bars rather than uniformly throughout. These notches are precisely positioned at locations where the tie bars need to be cut, allowing selective weakening at critical points while maintaining the integrity of other tie bar sections. This localized modification enables controlled cutting that buries the cut planes within the resin.
3Ease of operation
If low-strength portions are provided at tie bar boundaries, then tie bars can be easily separated, but the separation process becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-forming notches at the boundaries between tie bars and metal components before molding. These notches create low-strength portions that will easily break during the subsequent cutting operation. By preparing these weak points in advance, the separation process becomes simpler and more reliable, requiring less complex cutting mechanisms while ensuring clean separation at the intended locations.
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 reduces working hours and equipment costs, insulates the tie bar cut surfaces, and prevents oxidation, enhancing the air-tightness and quality of the insert-molded articles.
Implementation Method 1
separating the tie bars from the metal component by pressing tie bar cutting punches provided to the second mold against the tie bars to break the low-strength portions
Implementation Method 2
performing resin molding by injecting resin into a cavity surrounded by the tie bar cutting punches, the first and second molds being mold-clamped
Implementation Method 3
positioning the lead frame by means of pilot pins provided to the first mold
Implementation Method 4
holding the metal component by holding means provided to the first and second molds, by operating the first and second molds in a mold-clamping direction
Data Source
AI summary
Provides is a method of manufacturing an insert-molded article enabling to perform resin molding and tie bar cutting in one step and so as not to expose the cut planes of the tie bars to the external surface of the resin. A lead frame 1 provided with easily breakable notches 3a at positions closer to the metal component than the interfaces of tie bars 3 to be resin molded is prepared and positioned by means of pilot pins 11 provided to a lower mold 10. A metal component 4 is sandwiched between support protrusions 13 and component fixing pins 24 by lowering an upper mold 20 with the lead frame being positioned. Tie bar cutting punches 23 provided to the upper mold 20 are pressed against the tie bars, the tie bars 3 are separated from the metal component 4 by breaking the notches 3a, and the surroundings of the metal component 4 are filled with resin while the molds are closed. By this, the cut surfaces between the metal component 4 and the tie bars 3 are buried in the molded resin 7.