Tapered Protrusions Control Underfill Flow in Semiconductor Packages
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Solution Overview
Problem
In flip chip semiconductor package structures, the underfill material often bleeds or overflows during the underfill process, causing undesired issues by infiltrating other conductive structures on the substrate, which existing technologies fail to adequately prevent.
Innovation Solution
The semiconductor device package design incorporates a substrate with a surface angled at 90 degrees or another non-zero angle, featuring a gap or protrusion along at least three sides of the semiconductor device, which utilizes surface tension to control the underfill flow and prevent overflow by forming a specific contact angle that stops the underfill from spreading to other areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If underfill is applied to join semiconductor device and substrate, then bonding strength is improved, but underfill may bleed or overflow to other areas causing harmful effects
Solution Approach 1:
The substrate surface is segmented into a filling area and a non-filling area by forming protrusions with different surface heights. The protrusions create distinct regions that guide underfill flow to specific areas while preventing overflow to other regions, thus maintaining bonding strength without harmful overflow effects.
Solution Approach 2:
Different areas of the substrate surface are given different properties through the protrusion structure. The filling area has lower surface height allowing underfill penetration, while the non-filling area has higher surface height that repels underfill. This local differentiation enables precise control of underfill placement and prevents overflow to sensitive areas.
2Stability of the object's composition
If underfill is applied to tightly join semiconductor device and substrate, then joint tightness is improved, but underfill may infiltrate other conductive structures causing undesired issues
Solution Approach 1:
The substrate surface is divided into filling and non-filling areas using protrusions. This segmentation creates physical boundaries that confine underfill to the intended joint region, ensuring tight joining while preventing infiltration into other conductive structures located in the non-filling area.
Solution Approach 2:
The protrusions act as intermediary structures between the filling and non-filling areas. They serve as physical barriers that mediate underfill flow, allowing it to penetrate the joint area while blocking its path to other conductive structures, thus preventing harmful infiltration.
3Stability of the object's composition
If substrate and semiconductor device have perpendicular surfaces, then mounting stability is improved, but underfill control becomes more difficult
Solution Approach 1:
While maintaining perpendicular mounting surfaces for stability, the invention introduces local quality variations through protrusions with different heights. This allows the overall perpendicular structure to remain stable while the local protrusion features provide underfill control by creating filling and non-filling areas that guide and limit underfill flow.
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 effectively prevents underfill overflow by managing the surface tension and contact angle, ensuring precise placement of the underfill between the semiconductor device and substrate, thereby maintaining the structural integrity and electrical connectivity of the package.
Implementation Method 1
which utilizes surface tension to control the underfill flow and prevent overflow by forming a specific contact angle that stops the underfill from spreading to other areas
Data Source
AI summary
The present disclosure relates to a semiconductor device package including a substrate, a semiconductor device and an underfill. The substrate has a first surface and a second surface angled with respect to the first surface. The semiconductor device is mounted on the first surface of the substrate and has a first surface facing the first surface of the substrate and a second surface angled with respect to the first surface of the substrate. The underfill is disposed between the first surface of the semiconductor device and the first surface of the substrate. The second surface of the substrate is located in the substrate and external to a vertical projection of the semiconductor device on the first surface of the substrate. A distance between the second surface of the substrate and an extension of the second surface of the semiconductor device on the first surface of the substrate is less than or equal to twice a distance between the first surface of the semiconductor device and the first surface of the substrate. The second surface of the substrate extends along at least three sides of the semiconductor device.