Semiconductor Resin Mold Cull Layout for Uniform Cavity Filling
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Solution Overview
Problem
In semiconductor device manufacturing, the uneven melting of thermosetting resin in resin sealing molds leads to air trapping, affecting the resin's ability to fill the cavity and reducing sealing properties, due to the resin's variable melting rates and lack of fixed movement direction.
Innovation Solution
The mold design incorporates a cull with first and second flow passages that extend from the center and in a circumferential direction, respectively, with tapered shapes to increase heat receiving area and reduce viscosity, ensuring uniform resin flow and filling of cavities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermosetting resin is pressed into the cull and heated, then the resin melts and flows into the cavity, but the resin melts unevenly with slower melting at the center and faster melting at the outside, causing air trapping
Solution Approach 1:
The cull is divided into multiple heating zones with independent heating elements arranged in concentric circles. This segmentation allows different regions of the cull to be heated independently, enabling the center region to be heated more intensively to match the melting rate of the outer regions, thereby achieving uniform resin melting throughout the cull.
Solution Approach 2:
Different heating intensities are applied to different locations within the cull. The center region receives higher heating intensity compared to the outer regions, creating a non-uniform heating distribution that compensates for the slower heat conduction at the center. This local quality adjustment ensures that resin melts uniformly across the entire cull volume.
2Productivity
If the plunger presses the resin forward, then the resin is forced into the cavity, but the resin has no fixed movement direction and flows unevenly, reducing sealing properties
Solution Approach 1:
The heating elements are arranged in an asymmetric concentric circular pattern with different numbers of elements at different radii. The inner circle has fewer heating elements while the outer circles have more elements, creating an asymmetric heating distribution that guides resin flow more uniformly toward the cavity while maintaining high filling efficiency and reliable sealing properties.
Solution Approach 2:
The heating elements are arranged in concentric circular patterns within the cull, creating a radially symmetric curved heating distribution. This circular arrangement ensures that heat is applied uniformly in all directions from the center, promoting even resin melting and controlled radial flow toward the cavity, improving both filling efficiency and sealing quality.
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 design enhances resin fluidity and filling efficiency, preventing air trapping and improving resin sealing properties by ensuring consistent resin flow and complete cavity filling.
Implementation Method 1
The tapered shape increases heat receiving area, ensuring uniform resin flow by enhancing heat conduction to the resin
Implementation Method 2
a thermosetting resin is pressed against a top of a cull provided on the upper die and is melted
Data Source
AI summary
A mold of an embodiment includes a plunger, a cull, a plurality of cavities, and a plurality of runners. The plunger is provided inside an opening of one of upper and lower dies to be movable forward and backward in the up and down direction. The cull is provided on the other of the upper and lower dies to face the opening. The cavity is capable of receiving a semiconductor chip. The plurality of runners connect the cull to the plurality of cavities. The cull includes a plurality of first flow passages and a plurality of second flow passages. The first flow passage extends from a center toward a connection position with the plurality of runners. The second flow passage extends in a circumferential direction centered on the center. The second flow passage surrounds the plurality of first flow passage. The second flow passage is connected to the plurality of first flow passage.