Split Substrate Carrier With Adhesive Film For Flip-Chip Stacking
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Solution Overview
Problem
The challenge in microelectronics packaging is to reduce the dimensions of electronic packages while increasing functionality, which requires more complex integrated circuits and stacked dice, while maintaining effective encapsulation and preventing encapsulant leakage and contamination of solder ball pads.
Innovation Solution
A method involving a split substrate carrier with a removable adhesive film for containment, allowing for the stacking and encapsulation of multiple dice, using a hollow or two-part substrate to prevent encapsulant creep and ensure proper underfill, facilitated by precise registration and specialized molding compounds for efficient encapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple dice are stacked to increase functionality, then the functionality of the electronic device is improved, but the package thickness increases
Solution Approach 1:
The substrate carrier is divided into two separate carriers (first and second substrate carriers) that are positioned adjacent to each other. Each carrier supports a subset of the stacked dice, allowing the overall structure to be distributed across multiple segments rather than requiring a single thick substrate, thereby maintaining reduced package thickness while supporting multiple functional dice.
Solution Approach 2:
The patent transitions from a single-substrate vertical stacking approach to a dual-substrate lateral arrangement. By placing first and second substrate carriers side-by-side (in the lateral dimension) rather than stacking them vertically, the design accommodates more dice without increasing package thickness in the vertical direction, effectively moving the complexity to another dimension.
2Reliability
If encapsulant is used to protect the multi-chip device, then the reliability is improved, but the encapsulant may creep and contaminate solder ball pads
Solution Approach 1:
A gap is introduced between the first and second substrate carriers, acting as an intermediary space that physically separates the regions containing dice on each carrier. This gap prevents encapsulant from creeping across from one substrate carrier to another and reaching the solder ball pads on the opposite side, thereby eliminating the contamination pathway while still allowing the encapsulant to protect each individual multi-chip stack.
3Device complexity
If a single substrate carrier is used to support multiple dice, then the device complexity is reduced, but the encapsulant containment becomes difficult
Solution Approach 1:
The single substrate carrier is segmented into two separate substrate carriers positioned adjacent to each other. Each substrate carrier independently contains its own set of dice and can be separately encapsulated, making encapsulant containment straightforward for each segment. This segmentation transforms a difficult single-substrate containment problem into two easier, independent containment tasks.
Data Source
AI summary
A method of assembling a multi-chip electronic device into a thin electronic package entails inverting a flip-chip die arrangement over a hollow substrate, stacking additional dies on the hollow substrate to form a multi-chip electronic device, and encapsulating the multi-chip electronic device. Containment of the encapsulant can be achieved by joining split substrate portions, or by reinforcing a hollow unitary substrate, using a removable adhesive film. Use of the removable adhesive film facilitates surrounding the multi-chip electronic device with the encapsulant. The adhesive film can also prevent encapsulant from creeping around the substrate to an underside of the substrate that supports solder ball pads for subsequent attachment to a ball grid array (BGA) or a land grid array (LGA).