Vertical Bond-Wire Stacked Chip-Scale Package
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Solution Overview
Problem
The challenge in computing devices such as smartphones and tablets is the limited available space, which poses challenges for packaging and requires innovative solutions for memory-die stacks to optimize size reduction while maintaining functionality.
Innovation Solution
The implementation of a memory-die stack with vertical bond wires that breach a matrix at a landing surface, using a stair-step configuration and orthogonal wire bonding technology, along with a spacer and adhesive films to stabilize and position the bond wires, allowing for efficient assembly and reduced size without shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If memory dice are stacked vertically to reduce device size, then the volume of the memory module is reduced, but the complexity of wire bonding and assembly increases
Solution Approach 1:
The patent transitions from traditional planar wire bonding to vertical three-dimensional wire bonding. Bond wires are routed vertically through the stack rather than horizontally across the substrate, enabling memory dice to be stacked in the Z-direction. This dimensional change allows compact vertical stacking while maintaining manageable wire bonding complexity through automated vertical bonding processes.
Solution Approach 2:
The memory module is segmented into multiple discrete memory dice stacked vertically, with each die independently bonded to the substrate below it. This segmentation allows for modular assembly where each die can be separately processed and tested, reducing overall assembly complexity despite the vertical stacking configuration.
2Area of stationary object
If multiple memory dice are stacked in a compact arrangement, then space efficiency is improved, but the risk of electrical shorting between adjacent dice increases
Solution Approach 1:
The substrate serves as an intermediary between stacked memory dice, with bond wires making controlled contacts only at designated bond pads on the substrate surface. This intermediary structure ensures that electrical connections are established only at intended locations, preventing shorting between adjacent dice while enabling compact vertical stacking.
Solution Approach 2:
Bond wires are positioned with precise local control to contact only specific bond pads on the substrate, creating localized electrical connections. This localized bonding approach ensures that even in compact stacked arrangements, electrical pathways are strictly defined and isolated, preventing unintended shorting between adjacent memory dice.
3Productivity
If vertical bond wires are used to penetrate the substrate, then assembly efficiency is improved, but the difficulty of preventing wire shorting during assembly increases
Solution Approach 1:
Bond wires are pre-positioned and pre-bonded to the substrate at designated locations before memory dice are placed. This preliminary action establishes fixed reference points that guide subsequent die placement, ensuring precise wire positioning and preventing shorting while maintaining efficient assembly throughput.
Solution Approach 2:
The patent employs automated vertical wire bonding technology that replaces manual or semi-automated positioning methods. This mechanical substitution with automated bonding systems enables high-speed vertical wire formation with precise positioning control, simultaneously improving assembly productivity and manufacturing precision.
Data Source
AI summary
A system in package includes a memory-die stack in memory module that is stacked vertically with respect to a processor die. Each memory die in the memory-die stack includes a vertical bond wire that emerges from a matrix for connection. Some configurations include the vertical bond wire emerging orthogonally beginning from a bond-wire pad. The matrix encloses the memory-die stack, the spacer, and at least a portion of the processor die.