IC Package Solder Resist Structures for Cleaning Clearance
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Solution Overview
Problem
The increasing miniaturization and I/O density in integrated circuit packages lead to manufacturing challenges such as inadequate cleaning, voids in encapsulation, and electrical shorts due to reduced terminal spacing and pad densities, which reduce manufacturing yields and increase costs.
Innovation Solution
The integrated circuit package system involves forming a substrate with contact pads, a first conductor with a higher melting point, and a second conductor with a lower melting point, where the first conductor is over the contact pads and the second conductor is over the first conductor, allowing for reliable electrical and mechanical connections while preventing solder bridging and maintaining clearance for effective cleaning and encapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the terminal spacing and pad densities are reduced to increase I/O density, then the I/O density increases, but cleaning problems occur and manufacturing yields decrease
Solution Approach 1:
The patent introduces a vertical dimension by forming raised solder resist structures that extend upward from the substrate surface. This vertical protrusion creates additional space between adjacent terminals, allowing cleaning solutions to flow between terminals effectively while maintaining high I/O density on the substrate plane.
Solution Approach 2:
The solder resist material is applied with varying heights at different locations - specifically raised at terminal regions and lower or recessed in other areas. This localized variation in height provides targeted clearance for cleaning where needed while maintaining compact overall package dimensions.
2Quantity of substance
If the terminal spacing is reduced to increase I/O density, then the I/O density increases, but voids form in encapsulation and cleaning solutions cannot flow between terminals
Solution Approach 1:
The patent introduces a vertical dimension by forming raised solder resist structures that extend upward from the substrate surface. This vertical protrusion creates additional space between adjacent terminals, allowing cleaning solutions to flow between terminals effectively while maintaining high I/O density on the substrate plane.
Solution Approach 2:
The raised solder resist structures are formed before final encapsulation, preliminarily establishing clearance pathways that will guide cleaning solution flow and prevent void formation during subsequent manufacturing steps.
3Area of stationary object
If the package size is reduced for miniaturization, then the device size decreases, but the clearance for cleaning and encapsulation becomes inadequate
Solution Approach 1:
The patent resolves the clearance issue by utilizing the vertical dimension - raised solder resist structures extend upward to provide cleaning pathways without increasing the horizontal package footprint, thus maintaining miniaturization while ensuring adequate manufacturing clearance.
Solution Approach 2:
The solder resist layer is segmented into regions of different heights - raised portions at terminal areas for cleaning clearance, and lower portions elsewhere - allowing the package to maintain small overall dimensions while providing localized clearance where needed for manufacturing processes.
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 solution enhances manufacturing yield and reliability by preventing electrical shorts and ensuring adequate cleaning and encapsulation, thereby reducing costs and improving the efficiency of integrated circuit package production.
Implementation Method 1
forming a first conductor having a first melting point over the contact pad, forming a second conductor having a second melting point over the first conductor with the first melting point higher than the second melting point
Data Source
AI summary
An integrated circuit package system is provided including providing a substrate having a contact pad, forming a first conductor having a first melting point over the contact pad, forming a second conductor having a second melting point over the first conductor with the first melting point higher than the second melting point, and mounting a first device over the second conductor.