Query: PCB inspection solder paste

Candidate papers:

abstract: There is an increasing need for highly accurate 3D inspection and measurement capabilities for applications in SMT, semiconductor and metrology markets. 3D Multiple Reflection Suppression (MRS) sensor technology has been effectively combined with Automated Optical Inspection for several years and is now being utilized for many SPI applications such as microelectronics and sub 100 micron solder paste deposits and other challenging applications, like packaging, automotive, medical and other applications with stringent quality requirements. In addition to inspection, there is an increasing need to capture coordinate measurements inline. Phase shift profilometry (PSP) is widely used for 3D automated optical inspection (AOI) by electronics manufacturers assembling printed circuit boards (PCB) using automated surface mount technologies (SMT) Conventional PSP measurements are significantly challenged by inaccuracies caused by multiple reflections between surfaces on the inspected object. Multiple Reflection Suppression (MRS) sensor technology addresses this challenge. The sensor's unique optical architecture and the system's proprietary image fusing and processing algorithms provide fast, accurate 3D characterization capabilities that are well suited to other important applications, including solder paste inspection (SPI) and measurements typically performed by coordinate measurement machines (CMM) Coordinate measurements can now be attained in seconds, rather than the hours or days it would take a traditional coordinate measurement machine. MRS sensor technology provides significant advantages in speed, accuracy and resolution over the alternate technologies. This technology is a key building block for achieving high accuracy at production speed for Automated Optical Inspection (AOI) Solder Paste Inspection (SPI) and Coordinate Measurement (CMM) applications.
author_names: Dick Johnson

John Hoffman
title: Fast Accurate 3 D Sensor Technology for Automated Optical Inspection Solder Paste Inspection and Coordinate Measurements
year: 2018

abstract: The process of printing and inspecting solder paste deposits in Printed Circuit Boards (PCB) involves a very large number of variables (more than 30000 can be found in 3D inspection of high density PCBs) State of the art Surface Mount Technology (SMT) production lines rely on 100% inspection of all paste deposits for each PCB produced. Specification limits for Area, Height, Volume, Offset X and Offset Y have been defined based on detailed and consolidated studies. PCBs with paste deposits failing the defined criteria, are proposed to be rejected.
author_names: Pedro Delgado

Cristina Martins

Ana Cristina Braga

Claudia Barros

Isabel Delgado

Carlos Marques

Paulo Sampaio
title: Benefits of Multivariate Statistical Process Control Based on Principal Component Analysis in Solder Paste Printing Process Where 100% Automatic Inspection Is Already Installed
venue: ICCSA
year: 2018

abstract: The growth of the electronics industry led to a need for efficient methods of testing and validation of printed circuit boards (PCB) It is necessary to identify defects that might appear in a component in early production stages. This task may be performed by automatic inspection systems, showing advantages in speed, accuracy and repeatability, over human inspection. This paper describes a visual inspection system that is able to detect solder paste deposition defects on a PCB. The PCB image is analysed to segment the areas with solder paste and then, by comparing with reference data from the PCB design files, defects are identified, either because of missing or excess solder. The system is based on low cost components, namely a Raspberry Pi Compute Module and two Raspberry Pi v2 cameras. Experimental tests performed with the prototype, regarding the PCB defect detection and execution time, allowed to conclude the system can aid human visual inspection in a production line.
author_names: Guilherme B F Paulo

Luis Perdigoto

Sergio M M Faria
title: Automatic visual inspection system for solder paste deposition in PCBs
venue: 2021 Telecoms Conference (ConfTELE)
year: 2021

abstract: With the explosion in the electronics market, PCB manufacturing has taken a very important place. The manufacturers use Gerber file as the only reference for PCB drawing since it gives the most accurate details of the solder pads to be etched on the PCB. Due to this feature of the Gerber file, we are using it in our proposal of PCB inspection mechanism. Gerber is a text file specifying the shape, dimensions and coordinates of the solder pads. Firstly, it is parsed so that these details could be extracted. From this information, the locations are tracked on the PCB image captured and the corresponding solder pad is cropped. The amount of solder paste applied is calculated by computing the area covered by the solder pad. Correspondingly, the ideal area, as given by the Gerber file is found out. Upon comparison of these two areas, the various PCB defects like deficient, excessive can be found out. Displacement faults are found out by calculating the centroid of the different solder pads on the PCB and comparing with the locations given by Gerber.
author_names: Vediya Sitaram Raghuvanshi

A Burman

Prashant P Bartakke

Satish Deshpande
title: PCB solder pad inspection mechanism using gerber file
venue: 2016 International Conference on Communication and Signal Processing (ICCSP)
year: 2016

abstract: A solder printing inspection device (10) measures the volume of solder paste on a land on a PCB and sends inspection result information, including the measured volume, to an inspection data management device (102) From an image of the PCB after reflow, a solder attachment inspection device (30) extracts data on characteristics of the solder site being inspected, and said solder attachment inspection device communicates with the inspection data management device (102) to acquire the volume of solder paste at the point corresponding to the solder site being inspected, as measured by the solder printing inspection device (10) Said volume is then used to infer characteristics of nearby areas for which it is difficult to measure characteristics; the results of said inference are used together with the data on the abovementioned characteristics to compute the wetting height of the solder after reflow; and said height is classified as passing or failing.
author_names: Teng Jing Xin Ping

Hong Zhi Sen

Ke Qi Zhong Dao

Gu Shang Chang Shen
title: Solder attachment inspection method, solder attachment inspection device, and pcb inspection system
year: 2011

abstract: A solder printing inspection device (10) measures the volume of solder paste on a land on a PCB, and a solder attachment inspection device (30) measures the wetting height of the solder after reflow. Said solder attachment inspection device (30) contains: an inspection program which contains a plurality of evaluation criteria for evaluating the measured wetting height; and a selection rule for selecting from said evaluation criteria. Said selection rule defines which evaluation criterion to select depending on the volume of solder paste on the solder site being inspected, as measured by the solder printing inspection device (10) The solder printing inspection device (10) reads, from an inspection data management device (102) the solder paste volume corresponding to the solder site being inspected and determines the aforementioned evaluation criterion on the basis thereof.
author_names: Teng Jing Xin Ping

Hong Zhi Sen

Ke Qi Zhong Dao

Gu Shang Chang Shen
title: Solder attachment inspection method, pcb inspection system, and solder attachment inspection device
year: 2011

abstract: Quality inspection of PCB is a crucial stage in the assembly line as it provides an insight on whether the board works correctly or not. When the inspection is done manually, it is susceptible to human errors and is time consuming. The boards should thus be inspected at every stage of the assembly line and the process should be dynamic. This is achieved in this work through three crucial stages in the assembly line and by replacing the conventional manual inspection by using image processing to obtain a faster and more precise quality inspection. The solder paste inspection consists of preprocessing using blue plane conversion, comparing with the unsoldered board in blue color plane and post processing using overlay. The X ray inspection basically consists of preprocessing the captured image by RGB to gray conversion with thresholding, comparing with the expected image and post processing using overlay to show the shorts that has occurred along the assembly. The conformal coating inspection uses conversion of the blue intensity emitted off the board under UV light to RGB scale. Each of the algorithms were tested using 48 actual in production boards from Vinyas IT Pvt Ltd, a PCB assembly company based in Mysore. The processing time of the algorithms were found to be less than 2 seconds with an accuracy of 85.7% The system was also found to be cost eff ective over existing systems available in the market.
author_names: Dr P Madhan Kumar
title: Automated Quality Inspection of PCB Assembly Using Image Processing
year: 2020

abstract: In this paper, we introduce an automated Bayesian visual inspection framework for printed circuit board (PCB) assemblies, which is able to simultaneously deal with various shaped circuit elements (CEs) on multiple scales. We propose a novel hierarchical multi marked point process model for this purpose and demonstrate its efficiency on the task of solder paste scooping detection and scoop area estimation, which are important factors regarding the strength of the joints. A global optimization process attempts to find the optimal configuration of circuit entities, considering the observed image data, prior knowledge, and interactions between the neighboring CEs. The computational requirements are kept tractable by a data driven stochastic entity generation scheme. The proposed method is evaluated on real PCB data sets containing 125 images with more than 10 000 splice entities.
author_names: Csaba Benedek

Oliver Krammer

Mihaly Janoczki

Laszlo Jakab
title: Solder Paste Scooping Detection by Multilevel Visual Inspection of Printed Circuit Boards
venue: IEEE Transactions on Industrial Electronics
year: 2013

abstract: Detection of solder paste by image processing is a new approach in the solder paste inspection.image quality is one of the keys to ensure the accuracy of image detection.The image acquisition is a vital role for the protection of image quality.It's also a critical step in a series of processing steps to eventually obtain images useful information.This paper focuses on three main parameters of focal length,exposure and gain affecting the quality of solder paste image acquisition.The experimental demonstration of the reasonable range of the three main parameters of the focus,exposure and gain.As well as the functional relationship between shutter speed and gain.Providing a basis for the adjustment of solder paste image acquisition paramenters,but also laid the foundation for the follow up study for parameters adjustment automatically of the paste image acquisition.
author_names: Ye Hai
title: Solder Paste Image Acquisition Parameters of the PCB
year: 2012

abstract: Increased functional density and reduced input/output (I/O) spacing are the market trends in the electronics manufacturing industry. Industry reports indicate that approximately 50% 70% of soldering defects are attributed to the solder paste printing process for printed circuit board (PCB) assembly. Hence, after the printing process, a solder paste inspection (SPI) system is generally used to examine the amount of solder paste deposition. Effective selection of components and bonding pads during solder inspection is extremely important in achieving desired process cycle times and ensuring assembly yield. This paper uses the Mahalanobis Taguchi system to establish a systematic approach to determining guidelines for solder paste inspection. Among a total of 203 bonding pads on the board for a GPS product, the optimal model suggests that the solder deposition of 121 bonding pads be inspected. The reduction ratio is 40.4% and the feasibility of the proposed model is verified. Also, for those bonding pads to be inspected for their solder paste deposition, this study uses empirical data to define the specifications to effectively distinguish acceptable PCB samples from defective. The threshold is within the 100% capability for judgment of solder paste printing quality in the surface mount assembly process.
author_names: J C Huang
title: Reducing Solder Paste Inspection in Surface Mount Assembly Through Mahalanobis Taguchi Analysis
venue: IEEE Transactions on Electronics Packaging Manufacturing
year: 2010