Design for Product Build

Assignment 3

Covers Learning outcomes 4 & 5
Units 9–12
Notional workload 35 hours
Weighting 40%
Comments For information on submitting assignments, please refer to the AMI home page under Students, Assignments
Submission date Midnight at the end of study week 12
Please refer to the module planning chart for the date

Introduction

As described in the Module Descriptor, this module is assessed by three assignments, focusing successively on components and boards, on relevant ‘Design-for’ aspects for the board and assembly, and on making appropriate technology, materials and process choices at the system level. In Assignment 3 you will be looking at the partitioning choices and at the technologies, interconnection methods, assembly materials and processes used on a completed electronic product, and making recommendations for improvement.

In other words, Assignment 3 asks you to take a holistic view of the product, rather than building it from the ground up. This assignment also differs from the previous two in the significant respect that it gives you the freedom to choose your own “target product” to analyse, rather than presenting you with a specific design. We hope that this will enable you to choose a product that is of interest to you/your company.

Whilst our focus in Assignment 3 is primarily on Units 9–12, for this final assignment we would expect you not to confine your comments to material found in those Units, but to make comments and analyses that reflect the whole of your learning during the module.

Preliminary work

An essential preliminary activity is to select an example for analysis. Given the requirement to look at the choice of technologies and partitioning, this product should be more than just a single board in an enclosure. A typical product would have a number of different elements interconnected together, of which at least one will be a board assembly. An appropriate level of complexity is a personal computer, as a typical example contains modules and sub-assemblies, and the interconnections between as well as the motherboard.

If possible, you should choose a product where you have access to sufficient information to be able to determine the detail of the manufacturing processes. Ideally, if this is one of your own company’s products, or one which your company has either designed or assembled for others, you will be able to talk to engineers in the manufacturing chain. [As we comment elsewhere, manufacturers will generally respond positively to customers who are interested in understanding things from their point of view.]

Provided that the target product is of appropriate complexity, there are no limitations as to its application, end-use market, or volume of manufacture. Also, whilst you will need to describe the design in manufacturing terms, the electronic design is immaterial.

The nearer you can get to the manufacturing chain, the more you will be able to get out of the assignment, but this assessment task can actually be based on any piece of equipment of which you can obtain a sample, devise a viable mainstream route for manufacture, and understand sufficient of the application to be able to suggest an appropriate major change for the last element of the task.

Caution

It is important to make sure that your target product is really suitable for this assignment, and will allow you full expression for every part of the task. We recommend that you read the whole of this assignment carefully, and only then select your target product. It is well worth spending significant time on this preliminary work.

 

The task

Having chosen a target product, the task proper can be divided into five elements, in answering the first three of which you will need to explore exactly how the product is assembled, and carry out some analysis of any sub-assemblies.

Caution

Be aware that, whilst we have divided the first three elements into technologies, interconnection methods, and assembly processes, these aspects are intimately interrelated. You are advised to think carefully about the structure of your report when dividing up the information you collect.

 

1 Evaluate the choice of technologies used in the target product

The first element in the task is to examine the choice of technologies used. Most products will use silicon integrated circuits, soldered surface-mount board assembly, and some kind of interconnections, but others may use gallium arsenide components, thick film circuits, hybrids, multi-chip modules, press-fit connectors, flexible circuits, and so on.

Your evaluation should indicate which technology is used where, and explain the reason for its selection, as against choosing an alternative. For example, why a single-sided assembly with through-hole components has been used for one of the subsidiary modules, whereas the main board is a multilayer double-sided surface mount assembly.

We are looking for fairly detailed discussion of each of the technologies, for example differentiating between the use of area arrays as against gull-wing packages. Also, your evaluation should look at the validity of the selection of a particular level of technology and, if appropriate, make recommendations for changes that would improve manufacturability.

2 Evaluate the choice of interconnection methods used in the target product

The next element of the task is to look primarily at the interconnections used. A typical product will have a number of connections to the outside, as well as internal connections between different parts of the assembly. As with the choice of primary technologies, we are seeking to gain information on why a particular method was used, as against alternatives. For example, why plugs and sockets have been used instead of an integrated flex-rigid board.

As with the choice of technologies, you will get marks for valid recommendations for changes that would improve process, quality and yield.

3 Evaluate the choice of assembly processes used in the target product

In this next section you will be looking at the choice of assembly processes. Inevitably this focuses mostly on any printed circuit boards, although there are usually some choices at the system level.

In order to be able to describe the issues, you will need to include a flow diagram showing in detail the way in which the bare board is converted into an assembled and tested product, and the feedback and control systems used – depending on the complexity of the board, you may have to simplify this.

But this is intended to be a critical evaluation, and not just a description of the processes selected, so you are required to consider some of the alternative routes and processes, suggesting the basis on which the choice of process has been made, and making recommendations for changes that would improve process, quality and yield.

4 Evaluate the partitioning of the target product

By this time you will have a clear view of how the present product has been made, and be able to draw a block diagram of the divisions of the circuitry between its different elements. In this section of the task, we are asking you to look critically at the division of the electronic functions between the elements. By looking at possible alternatives, you should be able to articulate why the particular partitioning has been chosen, and perhaps even make recommendations for improvements.

And there are always alternatives: for example, the memory modules incorporated could be of a different size; a power supply could be built onto the board, rather than being a separate unit; video drivers or other interface circuits could be provided as plug-in options, rather than integrated onto a motherboard. For this activity, you need to think laterally about the options!

5 Effect of a major change

So far, you will have commented on the choices made for an existing product. Hopefully you will have been able to justify the decisions made, given the technology and materials available at the time the design was conceived. But, of course, technology moves on and requirements change, with the result that yesterday’s solution may not be appropriate for tomorrow’s application.

What we ask you to do now is to look again at your target product in the light of an appropriate major change to its application, advising management of the new “best case” choices for the new conditions.

What constitutes a major change will depend on the target product you have chosen. As examples:

Obviously this is not a complete list, but it should give the idea of what constitutes a major change. If you are in doubt on this aspect, talk to your tutor before you commence work on this assignment.

Your report on this section of the task should include a review of those elements that would be unchanged, as well as explaining and justifying the change you recommend to technologies, partitioning and the choice of interconnection methods and assembly processes.

Caution

As we said in Assignment 1, it is very easy to get intimidated by the apparent complexity of assignments like this. Just remember that this is as near as we can get to real life, but that what matters is learning from the experience! Approach your report-writing with questions such as: How is this product being made? Why did the designers make the choices they did? Are there ways in which the product could be made more manufacturable? What are the main features of the revised product that will impact on the way the design is implemented and manufactured?

We strongly recommend creating the framework first, and only then collecting the meat of the report.

 

Requirement

Compile a report containing your findings for each element in the assignment. This should be written and presented as a report that might be submitted to senior management to explain the current technologies, materials and processes, and what might be involved in a reworking of the design.

Note

A report is sufficient – it is not necessary to produce OHP foils or other presentation material of the sort you would use in real life when ‘placed on the spot’! However, you are expected to incorporate in your report appropriate explanatory graphical material, such as photographs, diagrams and flow-charts.

 

As a guide, you are unlikely to include all the points we expect to find if your main report has fewer than 2,000 words. There is no maximum word count as such, but excessive length may be penalised. In order to keep your script concise and well-argued, and its structure clear, you may find it helpful to provide relevant supporting material in appendices to the main report.

As always, you are strongly recommended to re-examine your draft report and conclusions to check that you have covered all the elements required in the report.

Bearing in mind that you will need to make reference to research findings in an appropriate and consistent way, we suggest that you use end-notes for references (leaving footnotes for incidental comments) and that you adopt one of the standard citation styles (see the links at http://www.lib.gla.ac.uk/researchskills/citationstyle.shtml for information). Also, given the transitory nature of some web sites, we recommend that you retain electronic copies of any material cited.

Marking scheme

The maximum marks available for each element of the report are as shown in the table below:

Element
Maximum marks
Critical evaluation of the technologies used
15%
Critical evaluation of the product partitioning
5%
Critical evaluation of the interconnection methods
10%
Critical evaluation of the assembly processes
20%
Analysis and recommendations relating to a major change
30%
Demonstration of research skills
10%
Quality of presentation (including introduction and conclusions)
10%

For information on grades, please refer to the AMI home page under Students, Assignments, Marks and Grades.

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