Multilayer PCB Warpage Simulation for Reflow Welding Quality

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Solution Overview

Problem

The challenge in multi-layer circuit board welding is the occurrence of warpage during the reflow welding process, which can lead to internal defects and affect the yield of circuit boards, as existing methods struggle to detect and address warpage in a timely manner.

Innovation Solution

A method and device that obtain warpage data using a shadow moire technique and simulate the welding process to generate a warpage level for each region of the circuit board, allowing for the adjustment of design parameters to prevent warpage, including the use of a preset welding temperature change curve and simulation modules to process the circuit board based on the warpage level.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multi-layer circuit board is used to stack components within limited space, then component installation space is improved, but warpage occurs during reflow welding process affecting yield

Engineering Contradiction:
Improvecomponent installation spaceVSAvoidcircuit board structure
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by performing warpage simulation before the actual reflow welding process. The system calculates warpage data for each circuit board layer under preset temperature change curves and simulates the stacked state to generate warpage levels, allowing designers to identify and mitigate warpage risks before production, thus preventing structural damage while maintaining multi-layer stacking capability

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If warpage is detected through measurement after welding, then warpage degree can be judged, but internal defects cannot be discovered in time affecting yield

Engineering Contradiction:
Improvewarpage degree judgmentVSAvoiddefect discovery time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs warpage simulation and evaluation before the actual welding process by calculating warpage data under preset temperature change curves and simulating the stacked circuit board state. This preliminary assessment allows internal defects to be identified in the design phase rather than after welding, eliminating the time loss associated with post-welding defect discovery while maintaining measurement precision through detailed warpage level analysis

Inventive Principle:
Principle #10Preliminary action

3Reliability

If warpage simulation is performed for each circuit board layer, then warpage risk can be identified, but processing complexity increases

Engineering Contradiction:
Improvewarpage risk identificationVSAvoidprocessing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the multi-layer circuit board into individual layers and calculating warpage data for each layer separately under preset temperature change curves. This segmented approach enables precise identification of warpage risks in specific layers while managing processing complexity through systematic layer-by-layer analysis rather than attempting to analyze the entire stacked structure as a single unit

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent manages processing complexity by changing parameters systematically - using preset temperature change curves with characteristic points, and generating warpage levels based on simulated stacked states. These parameter standardizations allow reliable warpage risk identification across multiple layers without proportionally increasing processing complexity, as the same methodology is applied consistently to each layer

Inventive Principle:
Principle #35Parameter changes

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 enables the dynamic analysis of warpage risk before actual welding, allowing for timely adjustments to ensure high-quality welding by identifying and mitigating warpage risks, thereby improving the reliability and efficiency of the circuit board production process.

Implementation Method 1

obtaining a shadow moire distribution diagram of the multi-layer circuit board under a grating through a shadow moire technique, and calculating a relative vertical displacement of the multi-layer circuit board during a welding process according to the shadow moire distribution diagram

Methodology Applied
Scientific EffectShadow moire technique: Moiré Effect

Data Source

PatentEP4068917A1Welding quality processing method and device, and circuit board
Publication Date: 2022.10.05 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP4068917A1 patent drawingFigure 1~2
  • EP4068917A1 patent drawingFigure 3~4
  • EP4068917A1 patent drawingFigure 5

AI summary

A welding quality processing method and device, and a circuit board are provided. The method includes: obtaining warpage data of each circuit board layer in a multi-layer circuit board under a preset welding temperature change curve; performing simulation according to a stacked state of the multi-layer circuit board and the warpage data to generate a warpage level of each region in the multi-layer circuit board in the stacked state; and processing the multi-layer circuit board according to the warpage level.