SMT Solver

Column from: Ray Prasad

Author of text book - Surface Mount Technology - Principles and Practice and over 100 papers, Mr. Ray Prasad is an inductee to the IPC Hall of Fame, the highest honor in our industry for his contribution to the electronics industry. He is also the recipient of IPC President's Award, SMTA Member of Distinction Award, Intel Achievement Award and Dieter W. Bergman IPC Fellowship Medal.

As the Lead Engineer, he introduced SMT into the airplanes and defense systems at Boeing and as SMT Program Manager, managed the global implementation of SMT at Intel Corporation when SMT was at its infancy. Mr. Prasad’s expertise includes all areas of SMT including SMT, Fine pitch, BGA, BTC and all aspects of SMT design and manufacturing.

In his consulting practice since leaving Intel in mid-90s, Mr. Prasad has helped many clients over the years in setting up brand new SMT manufacturing lines, process audits and yield improvement, in house DFM document development, legal disputes as technical expert  and teaching of in-depth SMT classes at OEM and EMS client sites across the globe.

He is currently the Chairman of three IPC Committees - IPC 7095 (Design and Assembly of BGAs), IPC 7093 (Design & Assembly of BTCs) and IPC 7530 (Reflow Profile Development). He also chaired and initiated the development of land pattern (IPC 782/7351) and baking and handling of moisture sensitive Plastic Packages (IPC 786/J-STD 20/33) to facilitate transition of assembly technology from through hole to SMT in early 80s.

Mr. Prasad received his BS in Metallurgical Engineering from the Regional Institute of Technology, Jamshedpur in India and MS in Materials Science & Engineering and MBA from the University of California at Berkeley. He is a registered Professional Metallurgical Engineer.
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October 27, 2021

SMT Solver: Flux and Cleaning—How Clean Is Clean? Part 2

The selection of flux and cleaning process determines, to a large extent, the manufacturing yield and product reliability of electronic assemblies. In this column, I will discuss cleanliness requirements to know whether the boards have been cleaned enough to meet their functional requirements for their intended applications.
July 07, 2021

SMT Solver: Flux and Cleaning—How Clean Is Clean? Part 1

In this column, Ray Prasad discusses the various types of fluxes and why we use them, followed by various types of cleaning materials and processes. In the next column, he will discuss cleanliness requirements to know whether the boards have been cleaned enough to meet their functional requirements for their intended applications.
June 29, 2021

SMT Solver: Optimizing Your Manufacturing Operations

We are not writing a book here but if you take a 50,000-foot view of the subject we should ask: What is the focus of manufacturing operations? The way I see it, there are only two things: quality and delivery. This is essentially the focus on the factory floor. Why? Because the customer cares about getting a quality product and getting it on time.
April 07, 2021

SMT Solver: Major Drivers for Improving Yield and Reducing Cost

In some of my previous columns I have gone into the details of types of defect that are predominant. There are many reasons we worry about defects, but the key reasons are increased cost and reduced reliability. These defects must be reworked so that you can meet the delivery requirement without too much delay.
January 07, 2021

SMT Solver: How to Audit OEM-EMS Assembly Capability, Part 3

Ray Prasad concludes his three-part series on how to audit OEM-EMS capability with questions on quality and RoHS compliance. The questions in this column are intended to help you generate your own questions relevant to your product and the manufacturing site you plan to audit.
November 08, 2020

SMT Solver: How to Audit OEM-EMS Assembly Capability, Part 2

During the past two decades, there has been a tremendous increase in outsourcing by OEMs to EMS companies, which also results in a decrease in yield. In this column, Ray Prasad focuses on the technology and manufacturing capabilities of the supplier.
September 13, 2020

SMT Solver: How to Audit OEM-EMS Assembly Capability, Part 1

In Part 1 of this three-part series, Ray Prasad looks into how to assess the manufacturing capability of any company—OEM or EMS—and provides an overview of the audit process.
August 02, 2020

SMT Solver: Industrial Revolution 4.0—Hype, Hope, or Reality?

If you are in the electronics industry, you cannot help but notice the discussion about Factory 4.0. Ray Prasad discusses Factory 4.0 as he understands it and invites readers' comments on his interpretation.
February 03, 2020

SMT Solver: Dealing With Package Parasitics

Packaging technology has constantly evolved over the decades from through-hole package to SMT with ever-decreasing pitches. There are many factors that play a role in the selection of a package, such as their cost and physical size, but the role package parasitics play in package selection has not changed over many decades.
May 15, 2020

SMT Solver: Developing a Reflow Profile

Developing a reflow profile involves ensuring all solder joints reach the minimum temperature to achieve good solder joints but don’t exceed maximum temperature to prevent damage to components or to solder joints. This is not an easy task. Ray Prasad provides specific guidelines and rules for developing a unique profile for each product without any damage and warpage to components and boards and with minimum possible profile related defects.
April 15, 2020

SMT Solver: Developments in BTC Guidelines: IPC-7093A, Pt. 1

As the chair of this IPC committee, let me share the latest developments in bottom-terminated component (BTC) design and assembly guidelines in this three-part series. In this first column, I will give you an overview of this technology and standard. In my upcoming columns, I will take an in-depth look at the design, assembly, quality, and reliability issues in BTC technology that have been incorporated in this latest IPC-7093A revision.
January 17, 2020

SMT Solver: Choosing the Right Defect

Ray Prasad addresses some key issues that are important for all of us to be aware of and learn about, especially for managers in SMT assembly and engineers who aspire to be future managers. Topics covered include choosing the right defect and developing a DFM and process recipe.
November 22, 2019

SMT Solver: Today’s Soldering Options

If you have to deal with mixed-assembly boards with both surface-mount and through-hole components—as is the case today for more than 95% of electronic products—the selection of a soldering process becomes more complex, especially if you use both tin-lead and lead-free components on the same board.
November 06, 2019

SMT Solver: How Standards Impact You and Your Company

Standardization is one of the key issues in promoting any new technology, but it is almost mandatory for SMT because of the need for automation to promote consistency in quality. Standards make the market grow faster than it would without them. A good standard benefits both users and suppliers. For example, if the package size tolerances are tightly controlled (within the requirement of the standard), the user can properly design the land pattern and use the same design for all suppliers of that package.
July 29, 2019

SMT Solver: Would You Prefer Shorts or Opens in Your Products?

Would you prefer shorts or opens in your products? Of course, neither. But what if you do have to choose? Ray Prasad says he would choose a more desirable defect, if there is such a thing. But what is a desirable defect? A defect that would never escape inspection and test and would be caught before shipping the product to the customer. Read on why.
June 17, 2019

SMT Solver: Benchmarking Defect Levels in Your Products

In this column, Ray Prasad discusses why zero defects may be a desirable goal but not a realistic one. He also shares some industry data as proof, which you can also use to benchmark defect levels in your products. Finally, he also addresses the choices when selecting components that have a big impact on the level of defects you should expect.
May 08, 2019

SMT Solver: Assemblers Can Help Customers Reduce Cost, Improve Reliability

It is commonly assumed that the level of defects is primarily dependent on how the assemblers control their manufacturing processes. This sort of mistaken belief will cause you to never find the root cause of the problem. Hence, the problem will persist forever. And just because defects are discovered in manufacturing does not mean that they were created in manufacturing. Find out why.
February 15, 2014

Flux Classification

In the previous column, I discussed flux functions and general considerations in their selection. In my next three columns, I will review various types of fluxes.
January 20, 2014

Major Types of Fluxes

Organic acid (OA) fluxes are stronger than rosin fluxes but weaker than inorganic fluxes.
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