Circuit Substrate Recess Design for Solder Distribution Control
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Solution Overview
Problem
The existing mounting structure for semiconductor elements on substrates with solder bumps faces challenges in adjusting the amount of solder flowing into grooves, leading to variations in the solder remaining on the top surface of electrodes, due to the lack of solder wettability on the inner surface of the grooves.
Innovation Solution
A circuit substrate design featuring a multilayer body with a first metal layer and a second metal layer having higher solder wettability, where the insulating layer defines a recess between the multilayer body and itself, allowing the solder to spread differently based on its amount, thereby controlling the solder's distribution and reducing variations on the electrode surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If grooves are formed in the mounting substrate to collect excess solder, then the solder can flow into the grooves, but the amount of solder remaining on the electrode top surface still varies because the inner surface of the grooves lacks solder wettability
Solution Approach 1:
The patent applies local quality by creating a multilayer body with different metal layers having distinct solder wettability characteristics. The first layer has lower solder wettability while the second layer has higher solder wettability, allowing different regions of the electrode to interact with solder differently and achieve controlled solder distribution.
Solution Approach 2:
The patent uses composite materials by combining multiple metal layers with different properties. The multilayer body consists of a first metal layer and a second metal layer, where each layer contributes different solder wettability characteristics, creating a composite structure that controls solder flow and distribution.
2Quantity of substance
If the inner surface of grooves is made with higher solder wettability material, then more solder flows into the groove, but it becomes difficult to control the amount of solder remaining on the electrode surface
Solution Approach 1:
The patent applies parameter changes by varying the solder wettability parameter across different layers of the multilayer body. The first layer has lower solder wettability while the second layer has higher solder wettability, allowing the system to control solder distribution by changing the wettability parameter in a controlled gradient rather than uniformly.
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 reduces variations in the solder amount remaining on the top surface of the electrodes by utilizing the differing wettability of the metal layers to control the solder's spread into the recess, ensuring a consistent final amount despite initial variations.
Implementation Method 1
the second metal has a higher solder wettability than the first metal... since the wettability of the solder is different between the first layer and the second layer, the amount of solder thereby determines how far the molten solder enters the recess
Data Source
AI summary
A circuit substrate that includes a substrate having a major surface, a multilayer body on the major surface, and an insulating layer that covers the major surface. The multilayer body includes a first layer and a second layer that overlies the first layer. The first layer is made of a first metal as a main material thereof, and the second layer is made of a second metal as a main material thereof. The second metal has a higher solder wettability than the first metal. As viewed perpendicular to the major surface, the insulating layer is spaced from and surrounds the surface of the second layer so as to define a recess between the multilayer body and the insulating layer.