Inkjet Dam for Semiconductor Underfill Bleeding Control
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Solution Overview
Problem
Conventional semiconductor packages face challenges in preventing underfill material bleeding, which can contaminate bonding pads and lead to assembly failures due to limitations in dam height and pattern formation during substrate manufacturing.
Innovation Solution
A semiconductor package with an inkjet-type dam formed on the substrate between the semiconductor chip and pad forming unit, featuring a rounded upper surface, varying patterns, and specific dimensions to effectively prevent underfill material bleeding, allowing for reduced package size and increased pad area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dam is formed on the substrate by printing solder resist during substrate manufacturing, then the dam can prevent underfill material bleeding, but the height of the dam cannot be increased sufficiently and various pattern shapes cannot be formed
Solution Approach 1:
The patent replaces the conventional mechanical screen printing method with an inkjet printing system that uses digital control and material jetting technology. This substitution enables precise control of dam height through digital parameters and allows formation of various pattern shapes by programming the inkjet head, while maintaining the function of preventing underfill material bleeding.
Solution Approach 2:
The patent changes the formation parameters of the dam by using inkjet printing with variable droplet size, deposition frequency, and layering control. These parameter changes enable independent control of dam height and pattern shape, overcoming the limitations of conventional screen printing where height and pattern are fixed by the mask design.
2Reliability
If a dam is formed on the substrate by printing solder resist during substrate manufacturing, then the dam can prevent underfill material bleeding, but additional methods must be used to form the dam
Solution Approach 1:
The patent makes the inkjet printing system multi-functional by using it for both marking letters on the chip and forming the dam structure. This single equipment performs multiple functions that previously required separate processes, thereby reducing overall manufacturing complexity while ensuring reliable prevention of underfill material bleeding.
Solution Approach 2:
The patent merges the dam formation process with the chip marking process by using the same inkjet printing system for both tasks. This consolidation eliminates the need for additional dedicated dam formation equipment and processes, reducing device complexity while maintaining effective bleeding prevention.
3Volume of moving object
If the package size is reduced to meet lightweight and thinner requirements, then the package becomes more compact, but underfill material bleeding may contaminate bonding pads
Solution Approach 1:
The patent applies local quality by forming a dam structure with specific height and pattern characteristics at the critical location between the chip and bonding pads. This localized high-height dam provides targeted protection against underfill material bleeding precisely where contamination risk exists, allowing overall package size reduction without compromising protection at critical areas.
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
The inkjet-type dam effectively prevents underfill material bleeding, enabling smaller package sizes and increased pad density, reducing the risk of contamination and assembly failures while maintaining adequate dam height and pattern flexibility.
Implementation Method 1
an upper surface of the dam is rounded due to surface tension
Data Source
AI summary
A semiconductor package includes a substrate which includes a chip mounting unit disposed on a first surface thereof and a pad forming unit disposed on an outer region of the chip mounting unit. The semiconductor package further includes a plurality of pads disposed on the pad forming unit of the substrate, a semiconductor chip disposed on the chip mounting unit of the substrate, a dam disposed on the first surface of the substrate between the semiconductor chip and the pad forming unit, and wherein the dam separates at least a portion of the pads from the semiconductor chip. In addition, the semiconductor package further includes an underfill material disposed between an active surface of the semiconductor chip and the first surface of the substrate and wherein an upper surface of the dam is rounded due to surface tension.