Concave Cap with Dam Member for Millimeter Wave Antenna Sealing
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Solution Overview
Problem
In semiconductor devices with built-in millimeter wave antennas, controlling the overflow of adhesive during sealing is extremely difficult, leading to adhesive attachment to wiring portions and affecting high-frequency transmission characteristics and antenna directivity.
Innovation Solution
A semiconductor device design featuring a concave cap with a dam-shaped member and a step portion on its sidewall to prevent adhesive overflow, where the sidewall thickness tapers from the outside surface to the bottom surface, and a dam-shaped member is provided between the conductor portion and the cap's inside surface to contain excess adhesive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive is applied to seal the cap, then the sealing function is achieved, but adhesive overflows to wiring portions affecting high-frequency characteristics
Solution Approach 1:
The cap structure is segmented into distinct functional zones: a sealing surface for adhesive application, sidewalls for containment, and a recessed portion for overflow management. This segmentation allows the adhesive to be confined to specific areas, preventing it from reaching wiring portions while maintaining effective sealing.
Solution Approach 2:
The sidewalls of the cap act as intermediary structures between the adhesive and the wiring portions. These sidewalls physically block and contain the adhesive within the recessed portion, serving as a protective barrier that prevents direct contact between the adhesive and sensitive wiring areas.
2Object-affected harmful factors
If adhesive application amount is strictly controlled, then overflow is suppressed, but control is extremely difficult
Solution Approach 1:
The cap is pre-formed with integrated containment features (sidewalls and recessed portions) before the adhesive application process. This preliminary structural preparation creates built-in barriers that automatically contain the adhesive, eliminating the need for precise control of adhesive application amount and simplifying the manufacturing process.
Solution Approach 2:
Instead of trying to prevent adhesive overflow through precise control, the design accepts that overflow will occur and provides a dedicated recessed portion to contain it. The potential harmful overflow is converted into a beneficial feature by directing it into a designated space that does not interfere with wiring portions.
3Reliability
If no dielectric material exists in wiring portions, then high-frequency transmission characteristics are maintained, but adhesive containment is difficult
Solution Approach 1:
The cap structure implements local quality by providing adhesive containment features (sidewalls and recessed portions) only in specific areas where adhesive application occurs. The wiring portions remain free of dielectric materials, maintaining high-frequency characteristics, while the cap locally provides the necessary containment structure where needed.
Data Source
AI summary
A semiconductor device includes a semiconductor element, a wiring board including a conductor portion formed on a first surface thereof on which the semiconductor element is mounted, the conductor portion being electrically connected to the semiconductor element, and a concave cap provided to seal the first surface of the wiring board, the concave cap being mounted through an adhesive on the first surface of the wiring boardIn the semiconductor device, a sidewall portion of the concave cap includes an inside surface facing toward the conductor portion of the wiring board, an outside surface positioned on an opposite side to the inside surface, and a bottom surface adhered onto the first surface of the wiring board. The sidewall portion of the concave cap is provided so that a thickness thereof becomes thinner at a portion extending from the outside surface to the bottom surface. Moreover, a dam-shaped member is provided between the conductor portion of the wiring board and the inside surface of the sidewall portion.