Casting Defects Analysis in Foundry and Their Remedial Measures with Industri...iosrjce
In this current scenario of globalization, foundries play a key role for manufacturing industries as
they are the major source of castings. As a key industry a foundry’s performance should be effectively high in
terms of production with minimum number of rejections. Castings are the major inputs for most industrial
products hence foundry industry is most indispensable. Casting is an integrated process considered as an
artwork with experienced professionals for high quality yield, even then in highly controlled environment
defects are dominant to take place leading to rejections, contrary to rejections a foundry’s key attempt is to
satisfy the demands neglecting quality levels. The challenges of casting defects are to be identifiedand
minimized for effective castings. This study provides an intense knowledge of critical casting defects and their
root cause analysis. In this paper efforts are made to achieve technically feasible remedies for minimizing
several casting defects and improving the quality of castings which will serve as control measures for quality
control professionals with zero defect concepts
Casting Defects Analysis in Foundry and Their Remedial Measures with Industri...iosrjce
In this current scenario of globalization, foundries play a key role for manufacturing industries as
they are the major source of castings. As a key industry a foundry’s performance should be effectively high in
terms of production with minimum number of rejections. Castings are the major inputs for most industrial
products hence foundry industry is most indispensable. Casting is an integrated process considered as an
artwork with experienced professionals for high quality yield, even then in highly controlled environment
defects are dominant to take place leading to rejections, contrary to rejections a foundry’s key attempt is to
satisfy the demands neglecting quality levels. The challenges of casting defects are to be identifiedand
minimized for effective castings. This study provides an intense knowledge of critical casting defects and their
root cause analysis. In this paper efforts are made to achieve technically feasible remedies for minimizing
several casting defects and improving the quality of castings which will serve as control measures for quality
control professionals with zero defect concepts
This paper discusses new developments in stencil laser and material technology and shows how these advancements, when combined, provide comparable and cost-effective alternatives to traditional electroformed stencils. The results are improved yields, cycle time reductions, and significant cost savings.
One of the challenges facing OEMs and CMs in building assemblies with miniature components is the stencil printing process. Many of today’s designs incorporate a mix of miniature and much larger components. Manufacturing engineers are faced with the dilemma of choosing a thinner stencil foil to ensure solder paste release for the miniature components or a thicker foil to ensure sufficient solder volume for the larger components.
This paper will present a rigorous method for evaluating the performance and economic benefits of solder paste stencil nano-coatings. Criterion such as underside cleaning, bridging, transfer efficiency across SARs, solder paste deposit geometry, post-print cleaning, and abrasion resistance of the coating, will all be considered and weighted. Performance of currently available coatings will be compared. A discussion of the economic impact on current and future SMT design will be included.
The objective of any rework process is to duplicate as closely as possible the original manufacturing
process while not disturbing neighboring components while still meeting the original specifications and
assembly criteria of the PCB .
The rapid assimilation of Ball Grid Array (BGA) and other
Area Array Package technology in the electronics industry
is due to the fact that this package type allows for a greater I/O count in a smaller area while maintaining a pitch that allows for ease of manufacture.
The intent of this study is to evaluate three step stencil technologies and measure their effectiveness in applying different volumes of paste on the same board during the printing process. The step technologies to be evaluated are chemically etched, laser welded and micro-machined. The step down areas for each technology will be physically measured for accuracy.
The intent of this study is to evaluate three step stencil technologies and measure their effectiveness in applying different volumes of paste on the same board during the printing process.
The Drill Geometry Influence on PCB Drilling PerformanceIJRES Journal
To adapt to the rapid development of PCBs, a high-property drill is desired. An applicable way is demonstrated by a design method based on analysis of drill structure, cutting force experiment , cutter wear observation to improve the drilling performance.Finally the drill wear is well improved by web thinning and chip dividing groove grinding.
This paper discusses new developments in stencil laser and material technology and shows how these advancements, when combined, provide comparable and cost-effective alternatives to traditional electroformed stencils. The results are improved yields, cycle time reductions, and significant cost savings.
One of the challenges facing OEMs and CMs in building assemblies with miniature components is the stencil printing process. Many of today’s designs incorporate a mix of miniature and much larger components. Manufacturing engineers are faced with the dilemma of choosing a thinner stencil foil to ensure solder paste release for the miniature components or a thicker foil to ensure sufficient solder volume for the larger components.
This paper will present a rigorous method for evaluating the performance and economic benefits of solder paste stencil nano-coatings. Criterion such as underside cleaning, bridging, transfer efficiency across SARs, solder paste deposit geometry, post-print cleaning, and abrasion resistance of the coating, will all be considered and weighted. Performance of currently available coatings will be compared. A discussion of the economic impact on current and future SMT design will be included.
The objective of any rework process is to duplicate as closely as possible the original manufacturing
process while not disturbing neighboring components while still meeting the original specifications and
assembly criteria of the PCB .
The rapid assimilation of Ball Grid Array (BGA) and other
Area Array Package technology in the electronics industry
is due to the fact that this package type allows for a greater I/O count in a smaller area while maintaining a pitch that allows for ease of manufacture.
The intent of this study is to evaluate three step stencil technologies and measure their effectiveness in applying different volumes of paste on the same board during the printing process. The step technologies to be evaluated are chemically etched, laser welded and micro-machined. The step down areas for each technology will be physically measured for accuracy.
The intent of this study is to evaluate three step stencil technologies and measure their effectiveness in applying different volumes of paste on the same board during the printing process.
The Drill Geometry Influence on PCB Drilling PerformanceIJRES Journal
To adapt to the rapid development of PCBs, a high-property drill is desired. An applicable way is demonstrated by a design method based on analysis of drill structure, cutting force experiment , cutter wear observation to improve the drilling performance.Finally the drill wear is well improved by web thinning and chip dividing groove grinding.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
Quality defects in TMT Bars, Possible causes and Potential Solutions.PrashantGoswami42
Maintaining high-quality standards in the production of TMT bars is crucial for ensuring structural integrity in construction. Addressing common defects through careful monitoring, standardized processes, and advanced technology can significantly improve the quality of TMT bars. Continuous training and adherence to quality control measures will also play a pivotal role in minimizing these defects.
Courier management system project report.pdfKamal Acharya
It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
Forklift Classes Overview by Intella PartsIntella Parts
Discover the different forklift classes and their specific applications. Learn how to choose the right forklift for your needs to ensure safety, efficiency, and compliance in your operations.
For more technical information, visit our website https://intellaparts.com
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
1. Choosing a Stencil
Is a stencil a commodity or a precision tool? A commodity is something that can be purchased
from many suppliers, with the expectation that the performance will be the same. A precision
tool is designed to perform a specific task, which, In the case of stencil printing, is to provide
defect-free printing. This article examines how to choose a precision stencil tool for printing.
By William E. Coleman, Ph.D. and Michael R. Burgess
In light of recent demanding requirements of lead-free printing and ultra-fine-pitch printing of
devices such as 0.4-mm microBGAs and 0201 chip components, a precision stencil tool is
required. The function of a stencil is to deposit solder paste, conductive polymer, glue, or flux
onto a substrate. Generally, the substrate is a PCB, but a silicon wafer is also used for printing
solder paste onto wafer pads for wafer bumping. Ball-placement tools - although not specifically
considered stencils - fall into the stencil domain. Instead of transferring paste through stencil
apertures, solder balls are positioned over a wafer or BGA substrate through stencil apertures.
For paste printing, the stencil printing process can be divided into three categories: the aperture-
fill process, the paste-transfer process, and the positional location of the deposited paste. All
three processes play a vital role in achieving the desired result - a precise volume of paste (a
brick) deposited to the correct location on the substrate.
2. Figure 1. Laser‐cut, no surface treatment, side wall.
The first step in printing solder paste is to fill the stencil aperture with paste. This is achieved
using a metal squeegee blade. Several factors can contribute to the aperture-fill process. The
orientation of the aperture with respect to the squeegee blade has an effect on the fill process. An
aperture oriented with its long axis in the same direction as the blade stroke does not fill as well
as an aperture oriented with its short axis to the blade stroke. Squeegee speed also influences
aperture fill. Squeegee speed must be reduced to fill the aperture with the long axis oriented
parallel to the squeegee stroke. The squeegee-blade edge has an influence on how well the paste
fills a stencil aperture. The rule of thumb is to print at the minimum squeegee pressure while still
maintaining a clean wipe of the solder paste on the stencil surface. If squeegee pressure is too
high, both the squeegee blade and the stencil may be damaged. Excessive squeegee pressure can
also cause paste smearing under the stencil surface. If the pressure is too low, one of two events
may occur. Paste left on the squeegee side of a small aperture will hold the paste, preventing its
release to the PCB pad, resulting in insufficient solder. Paste left on the squeegee side over large
apertures will be pulled down through the aperture, resulting in excess solder. Proper squeegee
pressure is the minimum pressure that achieves a clean wipe of the paste. Minimum pressure is a
function of blade type. A recent study demonstrated that the minimum squeegee pressure for one
squeegee blade* was about 40% of that of the teflon/nickel-coated blade for lead-free solder
paste. Tests have confirmed that lead-free solder pastes typically require about 25% more
squeegee pressure than tin/lead pastes.
3. Figure 2. Laser‐cut, electro‐polished side wall.
There are two primary considerations for solder paste release: the area ratio/aspect ratio for
stencil design and the type of stencil. The first is a function of stencil design, while the second is
a function of aperture-wall smoothness and side-wall geometry. The aspect ratio is the width of
the aperture divided by stencil thickness. It is generally accepted that an aspect ratio of 1.5 or
greater should achieve acceptable solder paste transfer. The aspect ratio is a useful guide when
the aperture length (L) is much larger than aperture width (W), such as greater than 5× the width.
BGAs, microBGAs, and 0201s have aperture dimensions where L and W are close to the same
value. These apertures are either circles and squares, or oblongs and squares with radius corners.
In all cases, the length is much less than 5× the width. It is more common to use the area ratio as
a guide to paste-transfer efficiency. The area ratio is the area beneath the stencil aperture
opening, divided by the area of the inside aperture wall. For a rectangular aperture, the area ratio
= [(L×W)/2(L+W)T)], where L and W are the aperture length and width, respectively, and T is
stencil thickness. For a square aperture, area ratio = S/4T, where S is the side of the square. For a
circular aperture, area ratio = D/4T, where D is the diameter of the circle. The generally accepted
rule is to achieve area ratios of >0.66 for paste transfer. This was true until the advent of
electroformed stencils. It is common with this technology to print apertures with area ratios
down to 0.50. One electroformed stencil** with relatively straight side walls and a smooth
mirror-like finish promotes greater solder paste release, which is helpful as component sizes and
pitches continue to decrease.
There are two primary stencil technologies used within the industry: electroformed and laser-cut.
Chemical etching can also be used to create steps for step stencils; however, final stencil
apertures are generally laser-cut. Three-dimensional (3-D) electroformed stencils are also
available for use when unique steps are needed, providing release qualities required for fine-
feature printing.
Figure 3. Laser‐cut, electro‐polished, nickel‐plated side wall.
Laser-cutting is a subtractive process. Traditional Gerber files are converted to CNC-type
language files that the laser can interpret. The final aperture shape and smoothness is impacted
by a laser-cutting machine, cut speed, laser power, beam spot size, and beam focus. Some laser-
4. cutting machines are homemade systems, some vintage lasers, and some are fine-cut laser
machines. Electro-polishing and nickel-plating are also used to further smooth surface walls and
improve solder paste release. Figures 1-3 demonstrate how successive surface treatment can
smooth out the surface wall to improve paste release. As a minimum, a stencil supplier should
electro-polish the laser-cut stencils.
Electroformed stencils are made by using an additive process. A nickel bath containing nickel
ions and a nickel-hardening additive is plated onto a mandrel to form the stencil. The process
begins by applying photo-resist to the mandrel. Next, a photo tool is plotted and placed over the
resist-coated mandrel. The resist is exposed and developed, creating small pillars of solder-resist
similar to solder paste bricks. As with any photolithographic process, a clean-room environment
with tight particle count and size control, as well as tight temperature and humidity control, is
needed to produce a high-quality electroformed stencil. Nickel is electroplated out of the bath
onto the mandrel one ion at a time around resist pillars until the desired thickness is achieved.
The resulting stencil has smooth, straight-wall apertures (Figure 4) that are precisely located and
capable of printing area ratios down to 0.50.
Figure 4. An electroformed stencil side wall.
An understanding of stencil-design factors impacting solder paste release is imperative to print
any solder paste successfully. The lead-free movement adds another variable that was not fully
understood in the early transition stages. It has been demonstrated that paste-transfer efficiency is
higher for tin/lead solder paste than lead-free. Therefore, stencil technology selection will
become more critical in achieving the best solder paste release and maximum transfer efficiency.
Using area ratio calculations will help designers and process engineers when selecting the proper
technology. When the area ratio is greater than 0.66, most laser-cut stencils can be used
successfully. However, if component and pad geometries require designs with area ratios
between 0.50 and 0.66, electroformed stencils should be considered. Figure 5 shows stencil
recommendations for a 5-mil-thick stencil. Curves are drawn for area ratios of 0.5, 0.66, and 0.9.
5. Figure 5. Area ratio chart with stencil technology recommendation.
If a particular aperture size lies below the 0.5 curve, aperture redesign is recommended by either
decreasing stencil thickness or increasing aperture size. If aperture design lies between 0.5 and
0.66, an electroformed stencil is recommended. Another useful tool is an area ratio
calculator,*** which gives the area ratio as an output once aperture size and stencil thickness are
inputted. An additional output of the area ratio calculator is recommended on stencil technology.
An example is the design of a stencil for printing 01005 chips. For a circular or rounded square
aperture of 7 mils., with a stencil thickness of 3 mils., the area ratio is 0.583; an electroformed
stencil is recommended.
Aperture Positional Accuracy
The positional accuracy of an aperture in the stencil determines how accurately a solder brick is
placed onto the PCB pad. Although this is important for tin/lead processes, it is even more
critical for lead-free processes. Printing off-pad can contribute to failures such as solder balls,
tombstones, opens, and shorts. Lead-free solder pastes do not wet and spread as well during
reflow. If the solder brick does not cover all of the pad, the paste typically will not flow out and
cover that portion of the pad.
Positional accuracy in a stencil is tied to the manufacturing process. In laser manufacturing, the
X/Y movement of the cutting beam must be controlled. Another factor is any stretching of the
pattern during stencil cutting or while mounting the stencil foil in a frame. This is especially true
for thin stencils having many apertures (a high percent of open foil area). The manufacturing
process is different for electroformed stencils. A photo tool is used to create the photo-resist
pillars that form apertures as nickel plates up around the pillars. The photo tool must be
processed and imaged in a tightly controlled temperature and humidity environment. Any
distortion (stretch/shrink) during electroforming or mounting processes must be compensated for
during the photo-tool creation. A recommended specification for both laser and electroformed
stencils is distortion (stretch/shrink) of <0.1 mils. per inch of an aperture pattern in X and Y.
Good process control during stencil manufacturing is necessary to meet this standard. It also is
important for the stencil vendor to certify the positional accuracy of each stencil shipped with the
appropriate high-end optical measuring equipment. It is possible to scale the stencil to match the
board to achieve positional accuracy. The stencil vendor who measures the board performs this
6. and creates a new stencil Gerber file to match the board. Typically, large boards (~18" × 24")
using lead-free solder paste may need stencil scaling to match the board.
Choosing a Stencil
Do all electroformed stencils perform alike? What about laser stencils? How can true stencil
performance be determined? The stencil end-user could conduct an in-house performance
evaluation for a number of stencils, or have an independent test laboratory do so. One method
would be to have various stencil vendors manufacture a stencil using the exact same Gerber file,
and compare stencil-print performance of each stencil. A recent study by an independent test
laboratory evaluated 12 stencils from 5 stencil vendors. Print performance was judged by solder
paste transfer and volume repeatability, as well as aperture positional accuracy. Five
electroformed stencils and seven laser-cut stencils were supplied. The electroformed stencils are
labeled 1, 3, 5, 7, and 9. Laser-cut stencils were labeled 2, 4, 6, 8, 10, 11, and 12. Laser-cut
stencil 2 was nickel-plated, while laser-cut stencil 11 was cut in an electroformed foil. Solder
paste volume was measured for 16 different SMT components including 0.4- and 0.5-mm
microBGAs, 0201s, and 0.4- and 0.5-mm-pitch quad flat packs (QFPs). Both tin/lead and lead-
free solder paste was used. A ranking system was devised in which a stencil received 12 points if
it had the highest paste-transfer efficiency for a specific component (maximum possible score of
192 if the stencil was in first place for all 16 devices), and 1 point for the lowest paste transfer
(minimum possible score of 16 if it was the lowest of all 16 devices). A stencil received 12
points if it had the lowest solder paste standard deviation, and 1 point if it had the highest.
Results are shown in Figure 6.
Figure 6. Ranking of stencils by print performance.
Positional accuracy was also measured (Figure 7). Stencils 1, 2, 6, 7, 11, and 12 gave acceptable
positional accuracy with ‹0.1-mils. per inch of distortion. Stencil 1 gave the best overall print
performance, followed closely by stencil 2.
7. Figure 7. Positional accuracy.
Conclusion
An electroformed stencil** with smooth aperture walls provided higher paste transfer and better
paste volume repeatability than the 11 other stencils evaluated. This broader process window is
important as smaller components push the area ratio below 0.66. There is a broad range of stencil
performance provided by the stencil industry. It is important to select a precision stencil tool,
rather than a stencil commodity, when processing small components and lead-free solder pastes.
*E-Blade squeegee blade, is licensed to Photo Stencil, Colorado Springs, Colo.
**E-FAB, a patented process of Xerox, is licensed to Photo Stencil, Colorado Springs, Colo.
***Area-ratio calculator: www.photostencil.com/arearatio.
For a complete list of references, please contact the authors.
William E. Coleman, Ph.D., vice president of technology, Photo Stencil, may be contacted at
(719) 535-8528; e-mail: bcoleman@photostencil.com.