Design for Product Build

Module overview

 

Introduction

Welcome to our module Design for Product Build, which aims to give you a broad understanding of how an electronic product is made, and an awareness of materials and process issues that will help you ask the right questions, make correct design decisions, and apply good practice to designs. We also hope that, by the end of your studies, you will have many insights into the requirements of board fabricators and assemblers and the issues which affect your supplier partners.

We don't yet have the planned video introduction, but here is the script . . .

 

 

The scope of the module

Earlier incarnations of this material (AMI4812 Processes and Materials for EDR and AMI 4813 Design for eXcellence) were developed primarily for designers working within the electronics industry; this module has been broadened in its scope to cover a wider range of professionals from other areas who need a broad picture of electronic manufacture. We hope that everyone interested in how electronics is ‘realised’ will find the course material illuminating. The module is also much more than a reworking, but extends the scope of the earlier material to cover all the stages between semiconductor back-end processes through to the assembly and test of a completed equipment enclosure.

The syllabus for the earlier modules was created by a team of industrialists, and this involvement with industry has continued throughout the development process of this module. The course contributors have benefited from materials, discussions and advice from a wide range of industrial partners, and many of the texts that are part of this distance learning module have been reviewed by our industrial partners in order to ensure accuracy, balance and a correct reflection of the state-of-the-art. Do take the time to visit our Acknowledgements page, and see just how many people have contributed to your studies.

Fit for purpose

The products that we make have to be “fit for purpose”, meeting the end-customer’s expectations for correct and continued function with the application environment. Achieving this demands that specifier, designer, layout engineer, and manufacturing engineer work together to devise an overall assembly that will perform consistently in its intended application over a sufficient life.

However, it is easy to take for granted the components, materials and processes that are used in board fabrication, in assembly and in equipment build, and we should not be surprised when products fail to perform as specified or, worse still, fail to function in some catastrophic way whilst in the field. In meeting that challenge, we have to know much more about the components, materials and processes, and not just succumb to the temptation to over-specify these, as this will have unwanted cost consequences.

Fit for manufacture

Designing a product involves making appropriate choices, not just to ensure product compliance, but also to achieve “fitness for manufacture”. What matters is not just the quality of the resulting product, but the cost of materials and processes, and the manufacturing yield, all of which influence the overall delivered cost of the product and its consequent profitability.

It is important that the design function takes full account of all subsequent activities, as the choices made in the initial phases of development determine the materials used, can put constraints on the processes used and their sequence, and will impact on the ease and cost of making modifications or repairs during life. The design will also influence the reliability of the product, with knock-on effects for the product marketing function, and a design that takes into account a wide range of customer needs (for example, by enhancing product flexibility and the upgrade paths) can even have a direct effect on potential sales.

So Design for Product Build affects everyone in the supply chain, from prototyping to end-of-life, and is also holistic, in that design, materials and processes are intimately related, with decisions made in one area having consequential effects elsewhere. The key challenge for the development team is to select the best options for materials and processes from among a wide range of possibilities. The choice will depend on the application, on the preferences of the “customers”, both internal and external, and on any constraints, such as the availability of materials, equipment and personnel. The decisions are frequently complex, and the subject of negotiation between the parties involved. To give a flavour of this, we have included in our final Unit a number of case studies, illustrating some of the issues.

Developments and trends

Not only is Design for Product Build holistic and complex, but it is also relatively fast-moving. Whilst many processes are mature, materials have undergone a continual improvement and the active components (the “silicon driver”) have made significant progress. Throughout the module we will be making reference to developments and trends and the way in which these impact on product design and manufacture.

As well as changes driven by the market and enabled by technology advances, there are also changes caused by legislative pressures, particularly in the environmental area. As an associated module AMI4982 Lead-free Implementation deals in some detail with the consequences for the electronics industry of such environmental pressure, in this module we have merely made passing reference to issues of waste, VOCs and the environmental challenges of board fabrication. However, with 1 July 2006 less than a year away at the time this module was being prepared, the soldering information has been revised from a lead-free perspective, as it is now lead-free materials that will be the major players, with eutectic tin-lead solders used only for special applications and legacy products.

Terminology

Some of the terms used in electronics manufacture are capable of bearing different interpretations, especially words like “fabrication” and “assembly”. In order to clarify our thinking, in the five main topic areas we have tried to use consistent descriptions:

In the same way, we distinguish between the various “Design fors”, separating Design for Fabrication (board level) from Design for Assembly (populated board) and Design for Mechanical Assembly (box build). Design for Test is a concept that covers the whole gamut from components through to the completed product.

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How the module is structured

Figure 1 shows the module contents in diagrammatic form. Units within the module are numbered 1 to 12, and you would normally study these in sequential order, as with other modules. However, when you examine the detail of our first two units on The Materials of Electronics and Enabling Processes, you will find that there is vastly more material than is consistent with the Study Plan. Our expectation is that much of this will already be familiar to you as a result of your industrial experience or previous study; our recommendation is that, in the first instance, you should merely familiarise yourself with the contents, referring back to these units at appropriate times during your study of the later sections of the module. For this reason, these two units are described in Figure 1 as “underpinning information”, whereas later units are referenced to specific assignments.

Figure 1: General arrangement of the module

Figure 1: General arrangement of the module

 

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Studying the module

This is a nominal 200-hour module. In other words, we anticipate a weekly commitment in the range 12–15 hours if you are to deal fully with the material. In the Study Plan below, we have indicated how you might set about your studies, grouping some of the activities to reinforce the fact that units are not necessarily the nominal 8–10 hours that is usual in other AMI modules.

The three assignments for this module have been spaced throughout your studies, both to avoid the pressure of a single final wide-ranging assignment, and to enable us to give early feedback as to your progress and the quality of your work.

Study week Unit Unit title
1 & 2 1
2
3
The materials of electronics
Enabling processes
Components
3 4 Board fabrication
4 Assignment 1
5&6 5
6
7
How design influences manufacture
Board assembly
Test
7 8 Requirements for manufacture
8 Assignment 2
9&10 9
10
11
The overall system
Alternative approaches
Developments and trends
11 12 Case studies
11 & 12 Assignment 3

Whilst the timetable is not “set in tablets of stone”, and two weeks slippage is allowed for holidays and similar, we would strongly advise that you attempt to keep to this timetable.

Be aware that there is an enormous amount of material in this module, most of which is referenced on the module map. However, much of this is supplementary, for those who lack the necessary background, and is not required reading for everybody – the extent to which you need to study the supporting material will depend very much on your background and experience.

We anticipate that most students will find that they need to study at least some topics in depth, whilst others can be skipped over, and would strongly recommend that you start your study of each unit by an initial skim-reading, familiarising yourself with the topic and the materials and then returning for more extended study. To make the decision on what to study in detail easier for you, in many cases we have introduced topics by asking searching questions, and suggesting appropriate answers.

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Accessing the module content

Each of the units has a main access page, which is a self-standing description of the topic, together with top-level information, self-assessment questions and activities. In some cases there will be a short introduction in the form of a Flash video file. Linked from this top-level unit page will be a number of resources and items to study. Everything you need to access will be linked to the page, but you will have to “drill down further” for some of the supplementary material.

To help you check that you have found all the materials, or in case you need to download/print information in advance if you are going away on business, we have created a site map for the module that identifies its main elements and key supplementary materials, but obviously not the answers to SAQs or activities.

There are three ways of accessing the top-level unit pages in the module, using the drop-down window that appears on the top right-hand side of each page, using the site map, or by following one of the links below. Notice that these will open the unit selected within the same window, whereas linked pages normally open a new window.

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Resources

Module materials

As explained earlier, each Unit has links to resources that are part of the module and are referenced from the top-level page. We recommend that you look at least briefly at all of these, if only to check that you are aware of the topic in sufficient detail.

Most Units also have links to pages with supporting information or detailed data. Much of this material explains basics such as metallurgy, surface tension, solder wetting, intermetallics and fluxes; although the module as a whole is pitched at postgraduate level, we do not assume that designers or managers know everything about the physical sciences. There is considerable variety in the format and length of these supplementary pages, and the longer items have inbuilt self-assessment questions.

[Note that some links are within the module site, but others are to the AMI topic resource area, because the resource was deemed to be potentially of use to those studying other modules. However, even if you become aware of these different locations, it should make no practical effect to your studies]

As with all specialist areas, electronics design and manufacture bristles with words that mean little to the outsider or, worse, mean something different within our specific context. We have therefore compiled a Glossary of terms used in electronics, which you may benefit from bookmarking. The introductory page has a comment on the use of PCB as against PWB, and an explanation of some confusing terms (lead, routing), and comments on dimensions and units. The bulk of the terms, however, are organised alphabetically, and accessed through the tabs at the top of every page.

Supplementary information

Most students will bring to this module at least an outline understanding of board fabrication and assembly technologies, and may even have visited a board fabrication shop or assembly house. However, if this is something with which you are not familiar, or your visit was a long time ago(!), you may like to look at our Fabrication and assembly process outline. Currently a “words and pictures” description, we are intending to replace this shortly with a better-illustrated page with video clips, to help overcome the increasing problem of student access to manufacturing processes, particularly for those working in companies that have manufacturing partners half a world away.

 

Where appropriate, we have taken advantage of agreements with industrial collaborators to incorporate material produced commercially. We have tried to keep the original look and feel of the source, and have only removed a small percentage of the content if it appeared to be overly commercial. Such externally-provided resources take a number of forms:

Realising that many students will not have ready access to board fabricators or assembly houses, we have tried to explain the processes as graphically as possible. In an increasing number of cases we have made use of short video clips. In some cases these are downloadable, but most are presented within a Flash window, together with appropriate explanation. Where the video records a verbal presentation, each clip is linked to a transcript provided in a text window.

Printing web material

Many students find it more helpful to print off material from the web than to study on-line. If this is your preference, it is perhaps worth pointing out the major differences between printing HTML pages and the Word or PDF documents that you will be used to. With Word and (especially) PDF you get a printed result that is more or less what the author intended; with HTML pages, the result depends both on the AMI style sheet and the settings on your PC. It is is well worth experimenting before you print off reams of paper, as the result is particularly sensitive to the size of font that you choose for your display. Even if you prefer View, Text size, Medium for your working display, selecting View, Text size, Smaller may give you a more visually-satisfactory printed result. And it will also save trees!

 

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Books and journals

During the course of preparing this module and its predecessors, we consulted an enormous number of books, only a few of which are listed in the Module Descriptor under Indicative Reading. The linked lists below give details of many more books, usually with a brief comment or overview, and in some cases there is a link to a review by Bob Willis at the SMART Group web site. We have a bias towards practical understanding, as will be evident from the comments. However, comparative lack of comment means simply that the books were initially read and reviewed at different times, and does not necessarily imply that one book is less useful than another.

The books cover a wide range of topics, all broadly in the area of electronic product design and manufacture, and with a materials and process focus suitable for the module. We hope you will find the lists a helpful starting point both for background reading and for continuing study during your career. The lists are organised alphabetically by main author within nine sections:

Many of the books will be in your company library (if you work for a large company) or can be borrowed from a local university library – talk to the Bolton Library for information on how we support distance learning students. We would, however, urge caution – with only 200 hours of study for this module, you will need to manage your time carefully, and will probably find these books more useful for longer-term reference than for immediate answers to your search.

Note that these lists have been developed over a number of years, and some older texts have been retained where their content is still relevant. The lists have however been reviewed for availability, and a dagger against the title indicates that the book is known to be no longer in print. However, such books may still be available from your local library or Learning Resource Centre or can be purchased on the second-hand market.

Traditionally, researchers have relied on “learned journals” as a means of providing information that has been peer-reviewed, and so represents the received wisdom of the academic community, but is available on a shorter time-frame than books. Such journals were sometimes membership-based, but others were available only on (expensive) subscription. In recent years, many of these materials have become available electronically, and are available through university subscriptions, rather than needing to be read at the library. If you have not already explored ATHENS, then you are recommended to visit the Bolton Learning Resources web site.

But even electronic editions of these journals find it difficult to keep pace with what remains a fast-moving industry. We recommend therefore that you spend at least some time familiarising yourself with trade publications in this area, as these are generally available free to qualifying readers, and are increasingly available electronically, both current issues and archives. In many cases you can also sign up for an email newsletter that will advise you of the arrival of the latest issue. Naturally, you have to be somewhat selective in your reading, and remember that contributors may have some commercial bias. But this was always true of books! What you will find in the best of these articles is a cogent explanation of a topic, combined with a current industrial insight. And, of course, such journals are a resource that will remain available to you long after your studies are finished.

There is an increasing number of trade publications, and you will find many of the more relevant titles listed on our Selected web sites: publications page.

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Web-based material

This module is intended to be self-standing as far as possible, but it makes references to a number of web-based resources, most of which are to the electronic archive of magazines and similar relatively stable sites. Please contact us if you find that key materials have disappeared, and we will provide you with access to back-up sources or equivalents.

Where we have linked to external materials, we would encourage you to look at most of those resources, rather than just skip over them. Whilst their value varies, there is usually some insight to be gained, and often the sites chosen have visual material that is not directly available for us to incorporate in this module.

Certain units in particular have a number of such links, some of which are more important than others. As an indication of which are the key items, we have used different colouring on the module map.

As part of your studies we hope that you will make use of web-based resources, and you will need to do this as part of some assignments. But be careful to assess the validity of information you uncover, and resist the temptation merely to collect vast swathes of data.

Health warning!

When you look for information on the web, using search engines, we recommend a degree of caution; it is very easy to get an unbalanced view, and easier still to get swamped. So, before you start, please read our note on using web resources.

 

Apart from any specific links that you will find in the units, we have created a number of lists of general resource material to which we have ourselves referred. These are grouped into:

These groupings are not mutually exclusive, particularly as most sites have at least some links pages. In creating the Entry tools page, we tried to interpret this as relating to sites that concentrate on providing links, but there is inevitably some duplication.

We try to focus your searches appropriately, but this only works until the sites and search engines change. Unfortunately, the rate of change on Web sites is enormous – probably of the order of 30% yearly. Please help us keep the listing up-to-date by emailing information on changed addresses and lost links to Martin Tarr. Also, as we don’t have a monopoly on serendipity, we are always grateful to receive URLs and descriptions of sites that you find during your browsing and which contain information that you have found of interest and relevance.

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Managing data

As well as managing your time, you will need to manage the data you collect, pulling together the information gained in the form of an easily-accessible note. There are a number of ways of doing this, and you could perhaps try several before settling on the one (or the combination) that is most appropriate for you:

You probably notice that all these ways are based on cutting down the amount of information to a manageable size, and arranging it so that it can be accessed with ease. We personally like the idea of having material in an electronic form that can be moved around and grouped so as to bring together material on similar themes. Apart from anything else, this highlights both common points and points of difference; you should not expect that all sources will concur – for example, on the subject of lead-free, there are frequent differences of opinion.

Our particular preference is for the use of mind maps, although you do not need to use software to get the benefit of what is a structured note-taking process. Information is available at this link, and we would encourage you to read it.

When making notes in whatever form, don’t forget to record the source:

We recommend you to bookmark web pages that you find of interest, so that you can return to them in the days to come. For those who like more flexible software solutions, MetaProducts Inquiry is an application integrated with Microsoft Internet Explorer that helps you to collect, organise, view and store information you find.

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Assignments

There are three assignments, for submission in Weeks 4, 8 and 12:

As always with assignments spread throughout a module, we recommend you to make an early start on the first assignment, and try not to fall behind. For this module, because there is inevitably some overlap in topics, and the relationship between units and assignments indicated in Figure 1 is a simplification, we recommend that you read all the assignments before you embark on detailed study.

Bear in mind also that there are requirements in all three assignments for you to demonstrate some research skills, providing evidence of reading and applying knowledge gained from outside the module. In order to do this, you will need to make reference to your findings in an appropriate and consistent way. We recommend you selecting and adopting one of the standard citation styles, such as MLA. Information on this topic may be found at http://www.lib.gla.ac.uk/researchskills/citationstyle.shtml. Also, given the transitory nature of some web sites, we recommend that you retain electronic copies of any material.

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Author/tutor profile

Martin Tarr is a specialist consultant engaged to author and tutor this module. He provides technical and marketing services to many companies in the electronics industry and also teaches with Napier University at the Scottish Advanced Manufacturing Centre. His area of interest covers all aspects of interconnect technology from semiconductor back-end processes through to equipment practice.

In over 35 years in the electronics industry, Martin has learnt the hard way how components are made and assembled into boards and systems, and how failure can occur both under adverse environmental conditions and what appears to be normal operation.

He has been intimately involved with custom applications of a wide range of technologies from valves to multi-chip modules, and in industries from avionics to heart pacemakers to industrial process control. In recent years, he has combined his technical/marketing consultancy with a commitment to teaching and has qualified as a registered practitioner of The Higher Education Academy.

 

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