Parylene Conformal Coating and Underfill Integration for PCB Rework

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Solution Overview

Problem

Current techniques for assembling electronic systems on printed circuit boards (PCBs) in harsh environments, such as wearable devices and IoT systems, face challenges with high costs and lack of flexibility due to separate application of conformal coatings and underfilling, which complicates the rework process and increases time and resources.

Innovation Solution

A method that combines conformal coating and underfilling using parylene as a conformal coating layer that also functions as a second underfill layer, along with a thermally reworkable underfill layer, and includes a release agent layer to facilitate rework, reducing costs and time-to-market by streamlining the assembly process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conformal coating and underfilling are applied separately, then protection against environmental conditions is improved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improveprotection against environmental conditionsVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines conformal coating and underfilling into a single integrated layer that simultaneously provides both functions. This eliminates the need for separate application processes, reducing manufacturing complexity while maintaining the protective and structural benefits of both conformal coating and underfilling.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated layer serves multiple functions: it provides environmental protection (conformal coating function) and structural support/gap filling (underfilling function) simultaneously. This multi-functionality reduces the number of components and processes needed in the manufacturing system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If conformal coating and underfilling are applied separately, then protection against environmental conditions is improved, but manufacturing cost increases

Engineering Contradiction:

Improveprotection against environmental conditionsVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

By merging conformal coating and underfilling into one application step, the patent reduces material costs, labor costs, and equipment requirements. The single integrated layer eliminates the need for separate material purchases, application processes, and quality inspection steps for two distinct layers.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If conformal coating and underfilling are applied separately, then protection against environmental conditions is improved, but assembly time increases

Engineering Contradiction:

Improveprotection against environmental conditionsVSAvoidassembly time

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent merges two sequential processes (conformal coating application followed by underfilling application) into a single simultaneous process. This integration directly reduces assembly time and increases production throughput while maintaining the protective benefits of both functions.

Inventive Principle:

Principle #5Merging (Combining)

4Reliability

If traditional conformal coating and underfilling processes are used, then environmental protection is achieved, but rework flexibility is reduced

Engineering Contradiction:

Improveenvironmental protectionVSAvoidrework flexibility

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

The patent segments the integrated conformal coating and underfilling layer into distinct functional zones or regions that can be selectively modified or removed during rework. This allows technicians to access and repair specific components without compromising the entire protective layer, thereby improving rework flexibility while maintaining environmental protection.

Inventive Principle:

Principle #1Segmentation

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

This approach enhances the resistance to harsh environmental conditions, reduces the time and cost associated with assembly, and allows for efficient rework of electronic systems, preserving components and PCBs during the process, thus enabling precise analysis of manufacturing defects or field failures.

Implementation Method 1

The conformal coating layer may be formed by applying vapor deposition polymerization (VPD) to parylene gas, the parylene gas may penetrate crevices and tight spaces

Methodology Applied

Scientific EffectVapor deposition: Physical Vapour Deposition

Implementation Method 2

causing pyrolisis of the vaporized dimer vapor to yield para-xylylene; and polymerizing the para-xylylene spontaneously on the PCB and the component affixed to the PCB

Methodology Applied

Scientific EffectPolymerization: Photopolymerisation

Data Source

PatentUS10356912B2Apparatus and method for conformal coating of integrated circuit packages

Publication Date: 2019.07.16 INTEL CORP

AI summary

An electronic system includes a printed circuit board (PCB), a component affixed to the PCB, and a conformal coating layer on the PCB and the component. The conformal coating layer includes parylene. Furthermore, the electronic system includes an underfill layer adjacent to the conformal coating layer, filling a gap between the PCB and the component. Other embodiments being described and/or claimed.