Molded IC Package Cavity Reliability via Segmentation
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Solution Overview
Problem
Conventional processes for forming IC packages with pre-molded cavities suffer from quality issues that affect the reliability of molded IC packages, particularly for sensitive devices like photodiodes and MEMS.
Innovation Solution
The solution involves an IC package structure and method that includes a leadframe with a die pad and leads, where a molding compound is used to form a molded package body that partially defines a cavity, allowing a second die to be attached within the cavity, and a lid is connected to cover the die, enhancing the package's reliability and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional molding techniques are used to encapsulate sensitive devices, then the manufacturing process is simple, but the reliability of the package is poor due to quality issues
Solution Approach 1:
The package structure is divided into distinct functional regions: a molded package body formed by molding compound, and a cavity region where sensitive devices are mounted. This segmentation allows the molded portions to provide protective barriers while the cavity exposes necessary leads and die pads, resolving the contradiction by improving reliability through protective encapsulation without requiring complete encapsulation that would compromise device functionality.
Solution Approach 2:
Different regions of the package have different encapsulation qualities: some areas are fully enclosed by molded compound for protection, while the cavity center remains open for electrical connections. This local differentiation of encapsulation quality allows the package to simultaneously achieve high reliability through protection where needed and maintain device functionality where exposure is required.
2Reliability
If pre-molded cavities are formed using inserts, then the cavity structure can be created, but quality issues arise that affect package reliability
Solution Approach 1:
The insert used in conventional pre-molded cavity formation is eliminated. Instead, the cavity is formed by strategically placing and molding around the die pad and leads, allowing the molding compound to define the cavity walls without requiring a separate insert component. This extraction of the insert simplifies the manufacturing process and eliminates insert-related quality issues while maintaining cavity formation precision.
3Object-affected harmful factors
If complete encapsulation is used to protect sensitive devices, then device protection is maximized, but electrical connections and device functionality are compromised
Solution Approach 1:
Instead of complete encapsulation, partial encapsulation is applied where the molded package body covers the periphery and provides protective barriers, while the center of the cavity remains open. This partial action provides sufficient protection from environmental factors while maintaining accessibility for electrical connections between leads, die pads, and mounted devices.
Solution Approach 2:
The package structure segments the encapsulation into protective molded portions and an open cavity center. This segmentation allows different regions to serve different functions: the molded portions protect against environmental factors while the open center enables electrical connections, resolving the contradiction between protection and accessibility.
Data Source
AI summary
A package is disclosed. The package includes a leadframe, and a first die, attached to the leadframe. The package also includes first bond wires, each attached to one of the first bond pads of the first die and to one of the leads of the leadframe, and a package body molded over each of a portion of the die pad of the leadframe, a portion of the leads of the leadframe, a first portion of the first die, and one or more of the first bond wires. The molded package body defines a cavity, and a second portion of the first die contacts neither of the die pad and the package body. The package also includes a second die having second bond pads, where the second die is attached to the first die. The package also includes second bond wires, each attached to the first and second die.