Stacked Semiconductor Package Underfill Structure Against Film Peeling
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Solution Overview
Problem
In semiconductor packaging, the use of adhesive films for mounting upper semiconductor chips can lead to process defects and voids due to the lifting or pushing away of the film during molding, resulting in poor reliability of the package.
Innovation Solution
A semiconductor package design featuring a package substrate with a receiving groove and an underfill member that includes multiple cover portions to fill gaps and cover exposed surfaces, preventing the adhesive film from being peeled off during molding, and a molding member that covers the chips and underfill member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive film is used to mount upper semiconductor chip, then chip mounting is achieved, but adhesive film peeling occurs during molding process
Solution Approach 1:
The patent introduces an underfill member as an intermediary substance between the adhesive film and the semiconductor chips. This underfill member fills the gap between the adhesive film and the lower chip surface, preventing direct contact between the molding compound and the adhesive film interface. The underfill member acts as a buffer that absorbs molding pressure and prevents adhesive film peeling, thereby resolving the contradiction between achieving chip mounting and maintaining adhesive film stability during molding.
2Volume of stationary object
If adhesive film is pushed away during molding, then molding compound can fill space, but voids and defects are trapped
Solution Approach 1:
The patent applies preliminary action by pre-filling the gap between the adhesive film and the lower chip surface with an underfill member before the molding process. This preliminary filling prevents void formation during molding, as the underfill member occupies the space that would otherwise be empty. The underfill member is applied in advance to ensure complete gap coverage, preventing molding compound from trapping voids and defects during the molding process.
3Temperature
If adhesive film is lifted during molding, then heat and pressure are applied, but adhesive film detachment occurs
Solution Approach 1:
The patent implements beforehand cushioning by placing an underfill member between the adhesive film and the molding compound. This underfill member serves as a cushion that absorbs and distributes the heat and pressure applied during molding. The cushioning effect prevents direct transmission of molding forces to the adhesive film interface, thereby preventing adhesive film detachment while still allowing necessary heat and pressure application for proper molding.
Data Source
AI summary
A semiconductor package includes: a package substrate having an upper surface and a receiving groove that has a predetermined depth from the upper surface; a first semiconductor chip disposed in the receiving groove; a second semiconductor chip attached to the first semiconductor chip, wherein the second semiconductor chip does not overlap a portion of the first semiconductor chip; an underfill member filling the receiving groove of the package substrate, wherein the underfill member includes a first cover portion and a second cover portion, wherein the first cover portion fills a gap between the first semiconductor chip and a bottom surface of the receiving groove, and the second cover portion covers the portion of the first semiconductor chip that is not overlapped by the second semiconductor chip; and a molding member covering the first semiconductor chip, the second semiconductor chip and the underfill member and disposed on the package substrate.