Exposed IC Circuitry Packaging Without Custom Cavity Molds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for exposing active circuitry in integrated circuits (ICs) often require costly custom cavity molds and modified process flows, increasing production costs and complexity.
Innovation Solution
Utilizing wafer level encapsulation (WLE) and film assisted molding (FAM) to create a cavity in IC packages, such as quad-flat no lead (QFN) packages, without the need for expensive mold tooling or process modifications, by bonding wafers and applying a mask layer to expose active circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If custom cavity molds and modified process flows are used to expose active circuitry, then the active circuitry can be exposed, but production costs and device complexity increase
Solution Approach 1:
The patent uses a sacrificial mandrel structure that is temporarily placed during packaging and then removed. This disposable approach eliminates the need for expensive custom cavity molds, as the mandrel is a simple, inexpensive structure that serves its purpose and is discarded. The mandrel creates the necessary cavity space without requiring complex mold tooling modifications.
Solution Approach 2:
The sacrificial mandrel acts as an intermediary object that facilitates the packaging process. It temporarily occupies the space where the cavity will eventually be, allowing standard packaging equipment and processes to be used. After the mold compound is applied and cured, the mandrel is removed, leaving the desired cavity. This intermediary approach avoids the need for modified process flows or specialized equipment.
2Manufacturing precision
If custom cavity molds are used to expose active circuitry, then the active circuitry can be exposed, but production costs increase
Solution Approach 1:
The sacrificial mandrel is an inexpensive, temporary structure that replaces costly custom cavity molds. It can be made from simple materials and does not require precision machining or specialized tooling. The mandrel is removed after serving its purpose, making the overall process more cost-effective despite the additional removal step.
Solution Approach 2:
The mandrel-based approach allows standard packaging equipment and processes to be used for exposing active circuitry, rather than requiring specialized custom molds. This universal approach means existing manufacturing infrastructure can handle the exposure process without additional capital investment in specialized tooling.
3Ease of manufacture
If standard packaging processes are used without modifications, then production cost is reduced, but active circuitry cannot be exposed
Solution Approach 1:
The sacrificial mandrel is placed in position before the mold compound is applied. This preliminary action prepares the packaging cavity space in advance, allowing standard packaging processes to be used. The mandrel ensures that when the mold compound is applied, it will naturally form around the mandrel and leave the correct cavity shape after removal, achieving precise circuitry exposure without process modifications.
Solution Approach 2:
The mandrel serves as an intermediary that enables standard packaging processes to achieve non-standard results (exposed circuitry). By using this temporary structure, the packaging equipment operates in its normal mode while still achieving the desired cavity formation and circuitry exposure outcome.
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
Provides a cost-effective method to expose active circuitry while minimizing package mold stress, allowing for efficient fabrication of ICs with exposed circuitry using existing package processes.
Implementation Method 1
The second surface of the first wafer is bonded to a surface of a second wafer by a die attach material that spaces the second surface of the first wafer apart from the surface of the second wafer
Data Source
AI summary
In one example, a method can include forming a mask layer on a first surface of a first wafer, forming a pattern in the mask layer to expose areas of the first wafer through the mask layer, and removing a substrate layer from the first wafer from the exposed areas of the first surface of the first wafer to expose a second layer of the first wafer or to expose dies. In another example, a method can include providing a cap over an area on a surface of a die bonded to and spaced apart from the surface of the die by a spacer, applying mold compound to encapsulate the die and at least a portion of the cap such that a surface of the cap remains unencapsulated, and removing at least a portion of a layer from the cap over the area of the die.