Cavity Substrate Solder Preforms for Reliable Package Interconnects
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Solution Overview
Problem
Conventional methods for interconnecting semiconductor components to cavity substrates using stencil printing of solder paste are inefficient and result in unreliable connections.
Innovation Solution
The use of solder preforms applied with flux to form solder bonds and fillets between semiconductor components and substrate terminals, which are then reflowed to create reliable interconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stencil printing method is used to apply solder paste onto terminals on a cavity substrate, then the process is simple and conventional, but the interconnection reliability is poor and mechanical stability is insufficient
Solution Approach 1:
The patent applies preliminary action by pre-forming solder joints using a solder preform before mounting the semiconductor component. The solder preform is positioned on the substrate terminals and reflowed to create pre-formed solder joints, which then serve as the connection medium when the component is mounted. This preliminary formation of solder joints ensures reliable interconnections while simplifying the overall manufacturing process.
Solution Approach 2:
The patent employs parameter changes by transitioning from a conventional stencil printing process to a reflow process using a solder preform. The key parameter change is the application of heat to reflow the solder preform, transforming it from a solid state to a molten state that then solidifies to form reliable solder joints. This parameter change (temperature application) ensures proper bonding and mechanical stability.
2Strength
If solder paste is applied using a stencil on cavity substrates, then the process can be automated, but the mechanical stability of connections is insufficient
Solution Approach 1:
The patent employs parameter changes by transitioning from a conventional stencil printing process to a reflow process using a solder preform. The key parameter change is the application of heat to reflow the solder preform, transforming it from a solid state to a molten state that then solidifies to form reliable solder joints. This parameter change (temperature application) ensures proper bonding and mechanical stability.
Solution Approach 2:
The patent utilizes phase transitions by heating the solder preform through a reflow process, causing it to transition from solid to molten state and then back to solid upon cooling. This phase transition ensures proper wetting, bonding, and formation of mechanically stable solder joints that securely connect the semiconductor component to the substrate terminals.
3Productivity
If conventional solder paste application is used on planar substrates, then the process is efficient, but it is ineffective for terminals in cavities
Solution Approach 1:
The patent applies local quality by using a solder preform that is specifically shaped and positioned to match the cavity geometry and terminal locations on the substrate. The solder preform is placed directly over the cavity terminals, ensuring that solder material is precisely applied only where needed. This localized approach ensures efficient and precise solder application for cavity substrates, overcoming the limitations of conventional stencil printing.
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 method enhances the mechanical stability and reliability of interconnections by forming solder fillets around the component terminals, providing stronger and more durable connections.
Implementation Method 1
reflowing the solder preform where reflowing the solder preform forms solder bonds to bond the component terminals to the substrate terminals
Implementation Method 2
solder bonding the component terminals to the substrate terminals where the solder includes solder fillets surrounding the component terminals
Data Source
AI summary
A semiconductor component package utilizing a cavity substrate is disclosed. The package effectively connects terminals of the semiconductor component to substrate pads on the semiconductor surface within the cavity using a solder preform. The solder preform is configured to fit the semiconductor component within a preform cavity. The solder preform is positioned over the pads on the cavity substrate and reflowed, forming interconnections between the semiconductor component terminals and the substrate pads. In addition, solder fillets are formed surrounding the semiconductor terminal to advantageously increase the strength of the interconnections, providing a more reliable semiconductor component package.