Semiconductor Package Molding Compound Height Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional stacked semiconductor packages face issues with mold flush during the molding process, leading to defects and low rigidity due to stress from solder ball melting, causing warpage of the substrate.
Innovation Solution
The method involves forming a semiconductor package where the height of the molding compound is smaller than the conductive elements, preventing mold flush and increasing substrate rigidity by encapsulating the entire surface, and using a mold with cavities that expose the top ends of the conductive elements to prevent pollution and enhance structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the molding process is performed to encapsulate the first chip and first wires by injecting molding compound into the cavity, then the chip and wires are protected, but the molding compound easily flushes out of the cavity and pollutes the ball-mounting area, causing defects
Solution Approach 1:
The invention divides the substrate surface into distinct functional areas: a first area for ball mounting that remains exposed and accessible, and a second area that is encapsulated by the molding compound. This segmentation prevents the molding compound from flushing into the ball-mounting area while still providing protection to the chip and wires in the encapsulated region.
Solution Approach 2:
Different regions of the substrate receive different treatments: the first area maintains a natural finish suitable for solder ball attachment, while the second area receives encapsulation for protection. This local differentiation ensures that each area has the specific properties needed for its function without compromising the other.
2Ease of manufacture
If the third solder balls are melted to form fourth solder balls connecting the second and first substrates, then the stacked package is formed, but stress is produced on the first substrate causing warpage
Solution Approach 1:
The invention applies a protective coating to the first substrate before the solder ball melting process. This coating acts as a cushioning layer that absorbs and distributes the stress generated during reflow soldering, preventing the substrate from warping while still allowing the formation of the stacked package structure.
Solution Approach 2:
The invention uses a composite structure consisting of the substrate, protective coating, chip, and molding compound. The protective coating serves as an intermediate layer that provides mechanical support and stress distribution, creating a composite system that maintains substrate flatness during the packaging process.
3Device complexity
If the mold cavity is used to accommodate the first chip and first wires, then the molding process can be performed, but the rigidity of the first substrate is relatively low causing it to be pulled and warped under stress
Solution Approach 1:
The invention introduces a protective coating as an intermediary layer between the substrate and the chip/wires assembly. This coating reinforces the substrate structure, providing additional mechanical support that prevents warpage while allowing the molding process to proceed normally through the cavity.
Solution Approach 2:
The substrate is enhanced with a protective coating to create a composite structure with improved rigidity. This composite material approach maintains compatibility with the existing molding process while fundamentally strengthening the substrate to resist warpage under stress.
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 prevents mold flush and increases the rigidity of the substrate, reducing defects and warpage, thereby enhancing the reliability and stability of the semiconductor package.
Implementation Method 1
forming a first molding compound to encapsulate the first surface of the first substrate, the first chip and parts of the conductive elements
Implementation Method 2
a reflow process is performed to form a plurality of fourth solder balls 22 by melting the third solder balls 21 and the first solder balls 15
Data Source
AI summary
The present invention relates to semiconductor package and the method of making the same. The method of the invention comprises the following steps: (a) providing a first substrate; (b) mounting a first chip onto a surface of the first substrate; (c) forming a plurality of conductive elements on the surface of the first substrate; (d) covering the conductive elements with a mold, the mold having a plurality of cavities accommodating top ends of each of the conductive elements; and (e) forming a first molding compound for encapsulating the surface of the first substrate, the first chip and parts of the conductive elements, wherein the height of the first molding compound is smaller than the height of each of the conductive elements. Thus, the first molding compound encapsulates the entire surface of the first substrate, so that the mold flush of the first molding compound will not occur, and the rigidity of the first substrate is increased.