QFN Package Top Lead Stacking Method
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Solution Overview
Problem
Existing quad flat non-leaded package (QFN) technologies face limitations in component stacking due to low reliability of internal welding joints and a structure that is not concise enough, hindering the miniaturization and high-density packaging of electronic components.
Innovation Solution
A method involving etching a metal plate to form a bond wire bench, processing a bump to a preset height, assembling a component, and packaging the metal plate in plastic to create a top lead, while etching the lower surface for a bottom lead, thereby forming a QFN package body with improved reliability and stacking capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Package in Package (PiP) or Package on Package (PoP) structures are used to achieve component stacking, then the density of electronic parts increases, but the reliability of internal welding joints deteriorates
Solution Approach 1:
The patent segments the package structure into distinct functional layers: a lower QFN package body containing first circuit elements, and an upper QFN package body containing second circuit elements. The segmentation is achieved through separate packaging processes where each package body is independently formed and then stacked, eliminating the need for complex internal welding joints within a single package. This structural segmentation resolves the reliability issue by replacing internal welding with external stacking of complete package units.
Solution Approach 2:
The patent implements a nested package structure where one QFN package body is stacked on another QFN package body, forming a hierarchical arrangement. The lower package body serves as the base layer, and the upper package body is positioned above it, creating a compact three-dimensional configuration. This nesting approach enables high-density component stacking while maintaining the integrity and reliability of each individual package unit, avoiding the welding joint reliability problems associated with traditional PiP or PoP structures.
2Volume of moving object
If traditional QFN package structures are used, then the package size is small, but the structure is not concise enough for efficient component stacking
Solution Approach 1:
The patent merges the advantages of small package size with efficient stacking capability by combining two complete QFN package bodies into a single stacked structure. Each package body maintains its standard compact QFN form factor, and the merging of these standardized units creates a concise overall structure that is optimized for both space utilization and manufacturing efficiency. This approach avoids the need for complex custom-designed package structures while achieving high-density stacking.
Solution Approach 2:
The patent transitions from two-dimensional planar arrangement to three-dimensional vertical stacking by positioning one QFN package body above another. This dimensional change enables efficient use of vertical space, allowing component stacking without increasing the footprint area. The resulting structure is concise and compact, maintaining small overall dimensions while providing multiple stacking levels for high-density electronic part integration.
3Quantity of substance
If Package in Package (PiP) structure with double plastic packaging is used, then component stacking is achieved, but the manufacturing process becomes complex
Solution Approach 1:
The patent applies preliminary action by completing the packaging of each QFN package body independently before stacking. The lower package body is fully packaged with its circuit elements enclosed in plastic, and the upper package body is separately packaged in the same manner. This preliminary packaging of individual units simplifies the overall manufacturing process by allowing parallel production and independent quality control, avoiding the complexity of double packaging operations required in traditional PiP structures.
Solution Approach 2:
The patent uses copying by creating identical or similar QFN package bodies that can be replicated and stacked. The standardized package design allows for consistent manufacturing processes to be repeated for each package unit, simplifying production. The upper package body is essentially a copy of the lower package body structure, enabling efficient manufacturing through process replication rather than requiring complex multi-step packaging operations.
Data Source
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AI summary
The present invention discloses a method for packaging a quad flat non-leaded package body, and a package body, and pertains to the field of packaging technologies. The method includes: etching an upper surface of a metal plate to process a desired groove and form a bond wire bench, a component bench, and a bump; processing the bump to reach a preset height, assembling a component on the component bench, and connecting the component and the bond wire bench; packaging the processed metal plate in plastic to form a package body, and exposing the surface of the processed bump on an upper surface of the package body to form a top lead; and etching a lower surface of the package body to process a desired bottom lead and obtain a quad flat non-leaded package body. In the present invention, a QFN package body with a top lead is formed, and therefore, large passive components can be stacked on the QFN package body while the high electrical performance and heat dissipation performance of the QFN package are exerted; the structure of the package body is simplified while the reliability of internal and external welding joints is improved; in addition, a plurality of components can be stacked through the top lead to overcome the limitations of component stacking.