Semiconductor Package Pad Layout for Thin-Substrate Warpage
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Solution Overview
Problem
Semiconductor devices with thin substrates experience warping and deformation due to thermal stress from differences in linear thermal expansion coefficients between the resin base material and copper films, leading to mechanical failures and reduced flatness.
Innovation Solution
The semiconductor device incorporates multiple metal pads on the resin base material to reduce the occupied area and thermal stress, with the light-receiving element connected via a first connection member to increase connection strength, and the conductive members bonded to metal pads to enhance bonding strength and reduce ultrasonic wave absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the substrate is made thin to reduce device height, then the device height is reduced, but thermal stress causes warping and deformation
Solution Approach 1:
The copper foil is divided into multiple separate metal pads instead of a single continuous layer. This segmentation reduces the total area of copper foil in contact with the resin substrate, thereby reducing thermal stress and preventing warping while maintaining electrical connectivity where needed
Solution Approach 2:
Metal pads are strategically positioned only at specific locations where electrical connection is required, rather than covering the entire substrate area. This local placement minimizes the occupied area and reduces overall thermal stress on the thin substrate
2Stability of the object's composition
If multiple metal pads are used to reduce thermal stress, then warping is reduced, but device complexity increases
Solution Approach 1:
The metal pads serve multiple functions simultaneously: they provide electrical connection between components, act as thermal management points, and serve as structural anchors that prevent substrate warping. This multi-functionality reduces the need for additional separate elements
3Strength
If connection members are bonded to metal pads using ultrasonic waves, then bonding strength is enhanced, but ultrasonic wave absorption reduces efficiency
Solution Approach 1:
The copper foil is segmented into multiple small metal pads, which reduces ultrasonic wave absorption compared to a large continuous copper layer. The smaller pad areas allow ultrasonic energy to pass through more efficiently while still providing sufficient bonding surface area for strong connections
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 configuration reduces thermal stress-induced warping, enhances connection strength, and improves bonding stability, thereby maintaining device integrity and reducing transmission loss in high-frequency signals.
Implementation Method 1
the conductive members bonded to metal pads to enhance bonding strength and reduce ultrasonic wave absorption
Data Source
AI summary
A semiconductor device includes a substrate, a light-receiving element, a switching element, a light-emitting element on the switching element, first and second conductive members. The substrate includes first to third metal pads on a front-side thereof. The light-receiving element includes first and second bonding pads on a front-surface thereof. A back-surface of the light-receiving element is connected to the first and second metal pads. The first and second bonding pads each overlap one of the first and second metal pads. The switching element includes front-side and backside electrodes and a control pad. The backside electrode is connected to the third metal pad. The first conductive member is connected to the front-side electrode of the switching element and the first bonding pad of the light-receiving element. The second conductive member is connected to the control pad of the switching element and the second bonding pad of the light-receiving element.