Stacked Semiconductor Device Plate Member Warping Prevention
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Solution Overview
Problem
The yield of stacked semiconductor devices is reduced due to warping of wiring substrates caused by thermal expansion differences, leading to inaccurate loading and resin encapsulation issues, resulting in resin burrs and defective connections.
Innovation Solution
A stacked semiconductor device design featuring a plate member with protruding strips and leg portions that directly contact the wiring substrate to stabilize it, preventing warping and maintaining consistent mounting height, thereby reducing resin burrs and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If divided semiconductor packages are fixedly bonded to plate members in sheet form to maintain productivity, then productivity is improved, but warping of wiring substrates occurs due to thermal expansion differences, leading to manufacturing precision degradation
Solution Approach 1:
A plate member is introduced as an intermediary carrier to hold multiple divided semiconductor packages. The plate member includes protruding strips that extend toward the wiring substrate and leg portions that contact the wiring substrate to suppress warping during thermal processing, thereby maintaining manufacturing precision while enabling high-productivity sheet-form handling
Solution Approach 2:
The plate member is designed with specific structural parameters: protruding strips extending toward the wiring substrate and leg portions contacting the wiring substrate. These structural parameters are optimized to suppress warping caused by thermal expansion differences between the wiring substrate and semiconductor element, maintaining manufacturing precision during thermal processing while enabling sheet-form handling for high productivity
2Ease of manufacture
If wiring substrates are heated during resin encapsulation, then resin encapsulation is completed, but thermal deformation occurs due to linear expansion coefficient differences, causing positioning accuracy to deteriorate
Solution Approach 1:
The plate member acts as a mediator between the wiring substrate and the external environment. Its protruding strips and leg portions physically constrain the wiring substrate during thermal processing, preventing thermal deformation and maintaining positioning accuracy while allowing the resin encapsulation process to proceed
Solution Approach 2:
The plate member applies preliminary counter-action to prevent warping before it occurs during heating. By having leg portions contact the wiring substrate and protruding strips extend toward it, the plate member preemptively counteracts the thermal expansion forces that would otherwise cause deformation and positioning errors during resin encapsulation
3Reliability
If semiconductor packages are handled in divided form for testing, then reliability is improved through performance testing, but device complexity increases due to sheet form assembly requirements
Solution Approach 1:
The semiconductor packages are segmented into divided units that can be individually tested and screened for reliability. These tested units are then assembled in sheet form on the plate member, combining the reliability benefits of individual testing with the productivity benefits of batch processing
Solution Approach 2:
The plate member serves multiple functions: it acts as a carrier for sheet-form handling, a support structure to prevent warping, and a positioning fixture during assembly. This multi-functionality reduces the need for separate fixtures and equipment, thereby reducing overall device complexity despite the segmented package approach
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 solution effectively suppresses thermal deformation and maintains accurate positioning during resin encapsulation, enhancing the yield and productivity of stacked semiconductor devices by preventing resin burrs and ensuring reliable connections.
Implementation Method 1
the wiring substrate in the semiconductor package is composed of a glass epoxy resin (13 to 40 [ppm]) or a copper foil used for wiring (15 to 20 [ppm]) having a higher linear expansion coefficient than that of the semiconductor element in the semiconductor package
Data Source
AI summary
A stacked semiconductor device includes a first semiconductor package and a second semiconductor package stacked thereon, and further includes a plate member interposed between the first semiconductor package and the second semiconductor package. The plate member has a plate body, protruding strips protruding toward its edges from the plate body, and leg portions respectively provided on the protruding strips. Each of the leg portions is disposed on a surface, which opposes one surface of a wiring substrate, of the protruding strip, and contacts the one surface of the wiring substrate. Thus, defective connection of connecting terminals due to warping of the wiring substrate and loading inclination of the first semiconductor package is reduced, resulting in an improved yield.