Package-on-Package Module Resin Block Positioning
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Solution Overview
Problem
In package-on-package modules with redistribution layers, achieving high positional accuracy and surface flatness is challenging due to component displacement during mold resin formation, especially when using solder or conductive paste, and polishing the mounting surface after resin formation is difficult.
Innovation Solution
A module configuration that fixes a resin block containing a component to a substrate using a fixing conductor and ensures flatness by polishing the resin block, with a redistribution layer connected via columnar conductors, and optionally includes a shield film for shielding and heat dissipation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a component is arranged on the lower surface side of the substrate using solder or conductive paste, then the module can achieve a package-on-package structure, but the component may be displaced due to pressure during mold resin formation
Solution Approach 1:
A resin block is introduced as an intermediary carrier to hold the second component. The component is mounted on the resin block using solder or conductive paste, and the resin block itself is then fixed to the substrate using a fixing conductor. This intermediary structure protects the component from direct pressure during mold resin formation while maintaining electrical connection through the fixing conductor.
2Area of stationary object
If a redistribution layer is formed with narrow gap and fine pitch, then high functionality can be achieved in small mounting area, but high positional accuracy is required for the component connected to the redistribution layer
Solution Approach 1:
The resin block serves as a precision positioning intermediary. By mounting the component on the resin block first and then fixing the resin block to the substrate with a fixing conductor, the system achieves high positional accuracy for the narrow gap and fine pitch redistribution layer connections without requiring direct high-precision mounting of the component to the substrate.
3Manufacturing precision
If the mounting surface is polished after forming the mold resin, then surface flatness can be ensured, but the process becomes difficult and complex
Solution Approach 1:
The resin block is designed with a pre-formed smooth upper surface that serves as the mounting surface for the redistribution layer. This preliminary preparation of the surface eliminates the need for difficult post-resin polishing operations, as the smooth surface is already provided by the resin block itself before the mold resin is formed.
Data Source
AI summary
Provided is a module which has a package-on-package structure including a redistribution layer and can be easily reduced in height. A module includes an upper module including a substrate, a first component, and a sealing resin layer, and a lower module including an intermediate layer and a redistribution layer. The first component is connected to the redistribution layer with a columnar conductor interposed therebetween and provided in the intermediate layer, and both the first component and a second component are rewired by the redistribution layer. By fixing a resin block containing the second component to a lower surface of the substrate by a fixing conductor, positional deviation of the second component can be prevented. Further, by polishing an upper surface of the resin block, it is possible to improve the flatness.