Flip-Chip Semiconductor Device Asymmetric Mounting Warpage Control
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Solution Overview
Problem
Existing semiconductor devices with flip-chip mounted chips on both surfaces of a wiring substrate face challenges in mounting on substrates with asperities due to small standoff height, leading to difficulties in Package on Package (PoP) structures and potential warpage issues.
Innovation Solution
A semiconductor device design featuring two semiconductor chips mounted on opposite surfaces of a substrate with conductive posts and solder balls, where the chips' long sides are parallel and perpendicular to the substrate, respectively, ensuring sufficient standoff and reducing warpage by using different sealing resin thicknesses and orientations to prevent substrate deformation during mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If semiconductor chips are flip-chip mounted on both surfaces of a wiring substrate, then packaging density is improved, but standoff height becomes insufficient for mounting on substrates with asperities
Solution Approach 1:
The patent transitions from a two-dimensional planar mounting approach to a three-dimensional structure by projecting conductive posts vertically from the wiring substrate. This dimensional change enables the conductive posts to extend beyond the substrate surface, providing sufficient standoff height while maintaining the flip-chip mounting configuration on both surfaces.
Solution Approach 2:
The conductive posts serve as an intermediary element between the wiring substrate and the mounting substrate. These posts provide both electrical connection and mechanical support, enabling the semiconductor device to be mounted on substrates with asperities by bridging the height gap that would otherwise be insufficient.
2Manufacturing precision
If conductive posts are projected from the wiring substrate to increase standoff, then standoff height is improved, but overall thickness increases more than needed
Solution Approach 1:
The patent optimizes the parameters of the conductive posts, specifically controlling their height and diameter to achieve the minimum necessary standoff height without excessive thickness. The sealing resin thickness is also adjusted to balance standoff requirements with overall device thickness, achieving a compromise that satisfies both mounting requirements and compactness.
3Adaptability or versatility
If semiconductor chips are mounted on both surfaces with different orientations, then degree of freedom in layout is improved, but warpage control becomes more difficult
Solution Approach 1:
The patent employs asymmetric mounting orientations for the semiconductor chips on opposite surfaces, with one chip mounted in a first direction and another chip mounted in a second direction perpendicular to the first. This asymmetric configuration increases layout freedom while the sealing resin thickness adjustment compensates for potential warpage effects.
Solution Approach 2:
The patent adjusts the sealing resin thickness as a compensatory parameter to control warpage. By modifying the sealing resin thickness, the device can accommodate different chip orientations and sizes while maintaining flatness and preventing excessive warpage that would interfere with mounting.
Data Source
AI summary
A semiconductor chip 10 flip-chip mounted on a first surface 32 of a wiring substrate 30, a semiconductor chip 20 flip-chip mounted on a second surface 33 of the wiring substrate 30, a sealing resin 71 covering the semiconductor chip 10, a sealing resin 72 covering the semiconductor chip 20, a plurality of conductive posts provided to penetrate through the sealing resin 72, and a plurality of solder balls mounted on second ends of the plurality of conductive posts exposed from the sealing resin 72 are provided; and the mounting directions of the semiconductor chips 10 and 20 are mutually different by 90°. Both of the planar shapes of the semiconductor chips 10 and 20 are rectangular shapes, the semiconductor chip 10 is mounted so that the long sides thereof are parallel to the long sides of the wiring substrate 30, and the semiconductor chip 20 is mounted so that the long sides thereof are perpendicular to the long sides of the wiring substrate 30.