Tapered Positioning Pin for Resin Encapsulation Accuracy
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Solution Overview
Problem
Existing semiconductor manufacturing methods for resin encapsulation of lead frames face challenges in achieving high accuracy positioning due to clearance between positioning pins and holes, leading to deformation and reduced positional accuracy, especially with the miniaturization of semiconductor devices.
Innovation Solution
The semiconductor manufacturing apparatus employs a tapered positioning pin with a larger outer diameter than the positioning hole and a pair of ejector pins arranged symmetrically, ensuring intimate contact and preventing deformation, while the ejector pins facilitate accurate disengagement without distorting the lead frame, thereby maintaining high positional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a predetermined clearance is secured between the positioning pin and positioning hole to prevent deformation, then the positioning hole deformation is prevented, but the positioning accuracy deteriorates
Solution Approach 1:
The positioning pin is designed with a tapered shape that transitions from a larger diameter at the top to a smaller diameter at the bottom. This dynamic geometry allows the pin to expand the positioning hole slightly during insertion (absorbing deformation stress) while maintaining intimate contact and high positioning accuracy during the molding process. The tapered configuration enables the pin to adapt to the hole dimensions rather than forcing a fixed clearance relationship.
2Manufacturing precision
If a movable mechanism is adopted in the positioning pin to reduce clearance and improve positioning accuracy, then the positioning accuracy is improved, but the mold structure becomes complicated and malfunctions may occur
Solution Approach 1:
The positioning pin employs a tapered geometric parameter configuration where the diameter varies along its length. This parameter change creates a self-adjusting mechanism that provides intimate contact for high accuracy positioning while preventing hole deformation through the gradual diameter reduction toward the base. The solution achieves the desired positioning precision through geometric design rather than complex movable mechanisms.
3Manufacturing precision
If the positioning pin outer diameter is increased to improve positioning accuracy, then the positioning accuracy is improved, but the risk of resin flow into clearance areas increases
Solution Approach 1:
The tapered positioning pin creates a dynamic fit where the larger upper diameter provides intimate contact for accurate positioning and prevents resin infiltration, while the smaller lower diameter reduces interference with the mold cavity. This gradient configuration allows the pin to maintain precise positioning without creating excessive clearance that would permit resin leakage.
Data Source
AI summary
A semiconductor device manufacturing apparatus for encapsulating with a resin a semiconductor chip includes upper and lower molds configured to receive therebetween a lead frame on which the semiconductor chip is mounted. A positioning pin provided to the lower mold is configured to be received by a positioning hole provided in the lead frame. Ejector pins provided in proximity to the positioning pin are arranged so as to be symmetrical with respect to the positioning pin.