Lead Frame Sandblasting Fixture for Precise Slit Roughening
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Solution Overview
Problem
Inadequate positional accuracy in surface roughening treatments on metal substrates leads to unintended roughening of outer surfaces, reducing yield and reliability of lead frames during manufacturing.
Innovation Solution
A sand blasting fixture with precise positioning components ensures accurate exposure of half-etched elongated slits on lead frames, allowing controlled sandblasting to form rough surfaces before or after a pre-coating layer, followed by press-molding with a polymer material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If surface roughening treatment is performed with insufficient positional accuracy, then the roughening process can be completed, but unintended locations on the outer surface are roughened, reducing yield and reliability
Solution Approach 1:
The fixture divides the sandblasting process into two separate operations: first exposing only the through trench areas, then exposing only the half-etched elongated slit areas. This segmentation ensures that each roughening operation targets only the intended locations, preventing unintended roughening and improving both positional accuracy and packaging reliability.
Solution Approach 2:
The fixture acts as an intermediary tool between the sandblasting machine and the lead frame. It uses cover plates with precisely positioned openings to control sand flow, ensuring that sand reaches only the intended areas (through trench or half-etched elongated slit) while protecting other surfaces from unintended roughening.
2Productivity
If the lead frame is completely exposed during sandblasting, then the entire surface can be treated, but the outer surface becomes roughened unintentionally, reducing product brightness
Solution Approach 1:
The sandblasting process is divided into two sequential steps with different exposure patterns: first step exposes only through trench areas, second step exposes only half-etched elongated slit areas. This segmentation allows efficient treatment of all required areas while protecting the outer surface from unintended roughening, maintaining product brightness.
Solution Approach 2:
Before the second sandblasting step, the fixture is reconfigured by removing or replacing the first cover plate with a second cover plate that has different opening patterns. This preliminary reconfiguration ensures that when the second sandblasting occurs, only the half-etched elongated slits are exposed, preventing unintended outer surface roughening that would reduce brightness.
3Device complexity
If a single cover plate is used for sandblasting, then the process is simpler, but it cannot achieve precise positioning for both through trench and half-etched elongated slit areas
Solution Approach 1:
The fixture uses multiple cover plates (first cover plate for through trench exposure, second cover plate for half-etched elongated slit exposure) instead of a single cover plate. Each cover plate is designed with specific opening patterns tailored to its function, achieving precise positioning for different areas. The segmentation of cover plate functions enables high manufacturing precision despite increased device complexity.
Solution Approach 2:
The fixture system achieves multi-functionality through multiple cover plates that can be selectively used or combined. The first cover plate handles through trench exposure, the second cover plate handles half-etched elongated slit exposure, and they can work together or independently depending on the processing step, providing universal coverage for different roughening requirements with high precision.
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
Maintains the smoothness of lead frame surfaces, enhances product brightness, and improves yield and packaging reliability by preventing unintended exposure during sandblasting.
Implementation Method 1
A plurality of sand grains are sprayed into the half-etched elongated slit in the sandblasting elongated hole by using the dry sandblaster so as to collide with the elongated step portion to form the roughed surface
Data Source
AI summary
A sand blasting fixture is used to allow a half-etched elongated slit of a lead frame to be processed a sandblasting operation, and includes a lower mold, an upper mold and a positioning component. The lower mold includes a lower cover plate. The upper mold includes an upper cover plate and a sandblasting elongated hole. The upper cover plate is removably covered by the lower cover plate, the sandblasting elongated hole is penetrated through the upper cover plate, and featured with the same appearance with the half-etched elongated slit. The positioning component is connected to the upper cover plate for fixing the lead frame on the upper cover plate so that the upper cover plate is allowed to completely cover one surface of the lead frame and the half-etched elongated slit is completely overlapped and exposes from the sandblasting elongated hole of the upper cover plate.