Characterization of the Solder Paste Release From Small Stencil Apertures in the Stencil Printing Process

2004 ◽  
Vol 127 (3) ◽  
pp. 340-352 ◽  
Author(s):  
Srinivasa Aravamudhan ◽  
Daryl Santos ◽  
Gerald Pham-Van-Diep ◽  
Frank Andres
Keyword(s):  
Printed Circuit Boards ◽  
Second Phase ◽  
Solder Paste ◽  
Circuit Boards ◽  
Stencil Printing ◽  
Ball Grid Arrays ◽  
Fine Pitch ◽  
Manufacturing Techniques ◽  
Two Phases ◽  
Print Process

Stencil printing is a critical first step in surface mount assembly. However, its robustness can be called into question because of the fact that about 50% or more of the defects found in the assembly of printed circuit boards (PCBs) are attributed to stencil printing 1. Manufacturing techniques for the assembly of certain flip chips, chip scale packages, 0201s, and fine pitch ball grid arrays are testing the limits of current stencil printing capabilities. This paper focuses on understanding the release of solder paste from the stencil, based on experimental and modeling approaches. The primary goal of the study is to characterize the performance of various aperture sizes and geometries based on release efficiencies and to compare them to predictions. The resulting model validation helps us better understand the print process for small features and offers options for increasing print yields. The study is divided into two phases. The first phase examines the release performance of various solder pastes from a variety of aperture sizes and geometries. The focus of this study is a comparison of square versus circular apertures when the nominal volume of paste to be deposited is kept constant. The second phase consists of developing a model that predicts paste-release efficiencies from small apertures and validating the model with experimental results.

scholarly journals Evaluation of The Printability of Lead Versus Lead Free Solder Pastes

2021 ◽  
Author(s):  
Ala Al Robiaee
Keyword(s):  
Printed Circuit Boards ◽  
Lead Free ◽  
Solder Paste ◽  
Circuit Boards ◽  
Stencil Printing ◽  
Printed Circuit ◽  
Main Factors ◽  
Free Solder ◽  
Print Process ◽  
The Impact

As the global marketplaces consider mandating lead-free equipments, many questions arise about the impact and feasibility of replacing lead in printed circuit boards soldering applications. In this project, the results presented of a study on comparing the process of screening lead paste versus lead free paste parameters for regular stencil printing using standard manufacturing methods. The key process parameters studies were: squeegee speed, squeegee pressure, and screening yield for both types of pastes. Two solder paste formulations (lead paste and lead-free paste) were evaluated in this study. The analysis of the pastes deposit volumes showed that for normal manufacturing range of printer (screener) settings (speed and pressure) tested the two pastes performed the same. The results also showed that the squeegee speed has a greater effect on the printing process than the squeegee pressure. The tests clearly showed that the lead paste was affected more by setting changes compared to the lead free paste. Varying the print speed and pressure for type of pastes by observing the resulting printed paste volumes optimized screening parameters. This study confirms that a new stencil or stencil design is not needed for the lead free paste. However, this study recommends a change to the sitting of the screening print process. Stencil cleaning frequency is one of the main factors that impact the production rate in an SMT line. The project highlights new results that lead free paste throughput will be less compared to lead paste at the screening step. The number of rejected boards screened with lead free-paste exceeded normal manufacturing standards. As stencil cleaning is a must function, it was recommended to increase stencil wiping frequency when lead free paste [is] in use in order to obtain a consistent volume with less screening defect.

scholarly journals Evaluation of The Printability of Lead Versus Lead Free Solder Pastes

2021 ◽  
Author(s):  
Ala Al Robiaee
Keyword(s):  
Printed Circuit Boards ◽  
Lead Free ◽  
Solder Paste ◽  
Circuit Boards ◽  
Stencil Printing ◽  
Printed Circuit ◽  
Main Factors ◽  
Free Solder ◽  
Print Process ◽  
The Impact

As the global marketplaces consider mandating lead-free equipments, many questions arise about the impact and feasibility of replacing lead in printed circuit boards soldering applications. In this project, the results presented of a study on comparing the process of screening lead paste versus lead free paste parameters for regular stencil printing using standard manufacturing methods. The key process parameters studies were: squeegee speed, squeegee pressure, and screening yield for both types of pastes. Two solder paste formulations (lead paste and lead-free paste) were evaluated in this study. The analysis of the pastes deposit volumes showed that for normal manufacturing range of printer (screener) settings (speed and pressure) tested the two pastes performed the same. The results also showed that the squeegee speed has a greater effect on the printing process than the squeegee pressure. The tests clearly showed that the lead paste was affected more by setting changes compared to the lead free paste. Varying the print speed and pressure for type of pastes by observing the resulting printed paste volumes optimized screening parameters. This study confirms that a new stencil or stencil design is not needed for the lead free paste. However, this study recommends a change to the sitting of the screening print process. Stencil cleaning frequency is one of the main factors that impact the production rate in an SMT line. The project highlights new results that lead free paste throughput will be less compared to lead paste at the screening step. The number of rejected boards screened with lead free-paste exceeded normal manufacturing standards. As stencil cleaning is a must function, it was recommended to increase stencil wiping frequency when lead free paste [is] in use in order to obtain a consistent volume with less screening defect.

scholarly journals Rheologically Assisted Design of Conductive Adhesives for Stencil Printing on PCB

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7734
Author(s):  
Ângelo D. M. Silva ◽  
Mariana M. Silva ◽  
Hugo Figueiredo ◽  
Isabel Delgado ◽  
Paulo E. Lopes ◽  
...  
Keyword(s):  
Printed Circuit Boards ◽  
Deposition Process ◽  
Solder Paste ◽  
Circuit Boards ◽  
Conductive Adhesives ◽  
Electrically Conductive ◽  
Stencil Printing ◽  
Rheological Analysis ◽  
Electrically Conductive Adhesive ◽  
Thermal And Electrical Properties

Driven by the need to deliver new, lead-free, eco-friendly solder pastes for soldering electronic components to Printed Circuit Boards (PCB), electrically conductive adhesives (ECAs) based on epoxy, carbon nanotubes (CNT), and exfoliated graphite (EG) were designed. The rheology of the adhesives prepared is paramount for the success of the deposition process, which is based on stencil printing. Thus, a rheological analysis of the process was first performed. Then, an experimental protocol was defined to assess the relevant viscoelastic characteristics of the adhesives for stencil printing application. Different composite formulations of epoxy/CNT/EG were produced. Their rheological characteristics were established following the designed protocol and benchmarked with a commercial solder paste. The thermal and electrical properties of the composite formulations were also characterized. As a result, a new, electrically conductive adhesive was delivered with potential to be an eco-friendly alternative to the solder paste currently used in stencil printing of PCB.

A Study of the Aperture Filling Process in Solder Paste Stencil Printing

1999 ◽  
Author(s):  
Jianbiao Pan ◽  
Gregory L. Tonkay
Keyword(s):  
Flip Chip ◽  
Deposition Process ◽  
Area Ratio ◽  
Solder Paste ◽  
Stencil Printing ◽  
Printing Process ◽  
Surface Mount ◽  
Fine Pitch ◽  
Main Indicator ◽  
Advanced Packaging

Abstract Stencil printing has been the dominant method of solder deposition in surface mount assembly. With the development of advanced packaging technologies such as ball grid array (BGA) and flip chip on board (FCOB), stencil printing will continue to play an important role. However, the stencil printing process is not completely understood because 52–71 percent of fine and ultra-fine pitch surface mount assembly defects are printing process related (Clouthier, 1999). This paper proposes an analytical model of the solder paste deposition process during stencil printing. The model derives the relationship between the transfer ratio and the area ratio. The area ratio is recommended as a main indicator for determining the maximum stencil thickness. This model explains two experimental phenomena. One is that increasing stencil thickness does not necessarily lead to thicker deposits. The other is that perpendicular apertures print thicker than parallel apertures.

scholarly journals Solder Paste Scooping Detection by Multilevel Visual Inspection of Printed Circuit Boards

2013 ◽  
Vol 60 (6) ◽  
pp. 2318-2331 ◽  
Author(s):  
Csaba Benedek ◽  
Olivér Krammer ◽  
Mihály Janoczki ◽  
László Jakab
Keyword(s):  
Visual Inspection ◽  
Printed Circuit Boards ◽  
Solder Paste ◽  
Circuit Boards ◽  
Printed Circuit

scholarly journals The Dissimilar Self-Alignment Characteristics of Smaller Passive Components in the Length and Width Directions

2021 ◽  
Vol 34 (2) ◽  
pp. 7-15
Author(s):  
Jingxi He ◽  
Yuqiao Cen ◽  
Yuanyuan Li ◽  
Seungbae Park ◽  
Daehan Won
Keyword(s):  
Printed Circuit Boards ◽  
The Self ◽  
Solder Paste ◽  
Circuit Boards ◽  
Passive Components ◽  
Component Placement ◽  
Width Direction ◽  
Before And After ◽  
Length Direction ◽  
Solder Paste Printing

Motivation: As passive components’ size gets smaller, quality rejects due to overhang and misalignment after the reflow appear more frequently. This situation is partly because the pass-fail criterion is set based on the offset concerning the component dimensions. Therefore, understanding the self-alignment characteristics of electronic components becomes very critical for surface-mount assembly yield. This research investigates the dissimilarity of self-alignment in the length and width directions. Approach: To avoid the argument of sample to sample variations, data are collected from 81 printed circuit boards (PCB) and 182,250 assembled components. Within a PCB, 25 different solder paste printing offset locations and 81 component placement offset settings are implemented. Component-placement positions before and after the reflow are monitored. The results are compared to identify different component sizes’ self-alignment characteristics in the length and width directions. Key findings: The misalignment of smaller passive components, e.g., R0402M(0.40 mm × 0.20 mm), is worse than the larger component under the identical solder paste printing and component placement conditions. Furthermore, the self-alignment characteristic in the length direction of these passive components, e.g., R0402M, to R1005M (1.00 mm × 0.50 mm) is superior to that of width direction. The observations are not consistent with the results found in earlier research that reported on larger components, e.g., C0402M(0.40 mm × 0.20 mm), to C3216M(3.20 mm × 1.50 mm).

scholarly journals ENSURING QUALITY OF INSTALLATION OF PRINTED CIRCUIT BOARDS BASED ON ORGANIZATION OF MACHINE-TO-MACHINE INTERACTION AND 3D-INSPECTION

2019 ◽  
Vol 1 (7) ◽  
pp. 35-41
Author(s):  
G. I. Korshunov ◽  
A. A. Petrushevskaya ◽  
P. S. Zaitsev
Keyword(s):  
Industry 4.0 ◽  
Process Model ◽  
Screen Printing ◽  
Printed Circuit Boards ◽  
Solder Paste ◽  
Circuit Boards ◽  
Machine To Machine ◽  
Automatic Installation ◽  
Printed Circuit ◽  
Machine Interaction

The article discusses the application principles of the industry 4.0 concept to improve the basic technological processes of electronics production. The problems of quality assurance in the automatic installation of printed circuit boards. Examples of the introduction optical inspections and fluoroscopy to reduce the marriage are given. The features of screen printing processes and their control using 2D and 3D inspections are considered. The location structure of the automatic optical inspection installations in the automatic line of printed wiring and communication of the automatic screen printing printer and 3D solder paste inspection is presented. A process model for the automatic installation of printed circuit boards using the elements of Industry 4.0 is presented. The organization of machine-to-machine interaction increases the automation of the system and eliminates the «human factor», as a result of which the production process is accelerated and the probability of occurrence erroneous actions resulting in nonconformities of products with standards is reduced. The tasks of organizing and certification of 3D fluoroscopy electronics, as well as the actual improving tasks the typical automatic assembly line of printed circuit boards, are considered.

Models for Reliability of Fine-Pitch BGAs and CSPs in Shock and Drop Impact

2004 ◽  
Author(s):  
Pradeep Lall ◽  
Dhananjay Panchagade ◽  
Yueli Liu ◽  
Wayne Johnson ◽  
Jeff Suhling
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Printed Circuit Boards ◽  
Drop Impact ◽  
Explicit Finite Element ◽  
Ball Grid Arrays ◽  
Fine Pitch ◽  
Plastic Ball ◽  
Model Predictions ◽  
High Speed Data Acquisition

Drop-induced failures are most dominant in portable electronic products. In this study, explicit finite element models have been used to study the transient dynamics of printed circuit boards during drop from 6 ft. Methodologies for modeling components using smeared property formulations have been investigated. Reduced integration element formulations examined include – shell and solid elements. Model predictions have been validated with experimental data. Results show that models with smeared properties can predict transient-dynamic response of board assemblies in drop-impact, fairly accurately. High-speed data acquisition system has been used to capture in-situ strain, continuity and acceleration data in excess of 1 million samples per second. Ultra high-speed video at 40,000 fps per second has been used to capture the deformation kinematics. Component types examined include – plastic ball-grid arrays, tape-array BGA, QFN, and C2BGA. Model predictions have been correlated with experimental data. Impact of experimental error sources on model correlation with experiments also has been investigated.

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