Spacer Element Solder Joint Distance Control
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Solution Overview
Problem
Legacy reflow processes for solder between components and substrates lack measures to maintain distance, leading to poor solder fatigue life, epoxy flow issues, and solder ball trapping, causing reliability concerns.
Innovation Solution
Incorporating spacer elements with a higher melting point than solder into the solder joints to maintain a desired distance between components and substrates during reflow, preventing solder collapse and allowing for easier removal of solder balls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If no spacer element is used during reflow, then the solder can flow freely to form strong joints, but the distance between components and substrates collapses leading to poor solder fatigue life and epoxy flow issues
Solution Approach 1:
A spacer element made of high-melting-point material is introduced as an intermediary between the solder and the component/substrate interface. The spacer maintains a controlled distance during reflow, preventing solder collapse while allowing adequate solder flow for strong joints. This mediator resolves the contradiction by enabling both sufficient solder flow for strength and distance maintenance for reliability.
Solution Approach 2:
The melting point parameter of the spacer material is specifically selected to be higher than both the solder and epoxy curing temperatures. This parameter change allows the spacer to remain solid during reflow and epoxy curing, maintaining distance control while permitting the solder and epoxy to flow and cure properly. The specific melting point parameter resolves the contradiction between allowing flow and maintaining structure.
2Ease of manufacture
If the distance between components and substrates is reduced during reflow, then solder ball trapping is more difficult, but epoxy flow underneath components is compromised causing reliability concerns
Solution Approach 1:
The spacer element performs preliminary action by maintaining the optimal distance between component and substrate before epoxy curing begins. This pre-established spacing ensures that when epoxy is applied, there is sufficient space for proper flow and curing underneath the component, preventing reliability issues while still allowing solder ball access.
Solution Approach 2:
The spacer acts as a mediator that maintains the precise gap needed for both solder ball access and epoxy flow. By controlling the distance, the spacer enables manufacturers to remove solder balls easily while ensuring epoxy can flow underneath components for reliable encapsulation, resolving the contradiction between ease of manufacture and reliability.
3Reliability
If spacer elements are added to maintain distance during reflow, then solder fatigue life and epoxy flow are improved, but the device complexity increases
Solution Approach 1:
The spacer element is designed as a simple, inexpensive, spherical object made from readily available high-melting-point material. Although it adds a component to the joint structure, the spacer is simple in form (a sphere), inexpensive to produce, and serves a single temporary purpose during manufacturing. This simplicity and low cost offset the increased structural complexity, resolving the contradiction between reliability improvement and device complexity.
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
Enhances solder fatigue life, improves epoxy flow, and prevents solder ball trapping, thereby increasing the reliability of the assembly process.
Implementation Method 1
Incorporating spacer elements with a higher melting point than solder into the solder joints to maintain a desired distance between components and substrates during reflow
Data Source
AI summary
Apparatuses, systems, and methods associated with spacer elements for maintaining a distance between a substrate and component during reflow are disclosed herein. In embodiments, a substrate assembly may include a substrate and a component. The component may be coupled to the substrate via a solder joint, wherein the solder joint may include a spacer element and solder, the spacer element to maintain a distance between the substrate and the component. Other embodiments may be described and/or claimed.