How to develop an electronic device according to the principles of DFM

DFM (design for manufacturing) - these are the principles of development, which are aimed at the successful production of the finished product. It would seem that the design of any electronic device should take into account the production capabilities, but in practice this is not always the case. A novice development team can get a device at the output, which becomes a source of various problems at the production stage, up to the impossibility of making it based on available technologies. What issues need to be addressed in the design process of electronics to reduce the risks at the final stage of the project? We will answer this question in this article.

The starting point at the start of the development of the device is the implementation of a certain functionality and working conditions laid down in the technical task. These parameters set the requirements for hardware and software, determine the appearance of the case. Also, the device requirements for reliability and maintainability, because no one wants to get the output from the conveyor device, which only works in laboratory conditions before the first failure. Additional restrictions for developers - tight deadlines and minimization of financial costs. How best to combine all these requirements in a single project? The answer to this question lies in the principles of DFM, which set the approach to the development of the device, taking into account the technological requirements of production.
')
The DFM requirements focus the developer’s attention on the final stage of the project — in production — and force him to gather information about the device and technological capabilities of the production line even before the design work begins. Of course, to implement such an approach, engineers must have the appropriate qualifications and experience in successfully manufacturing the devices they have developed.

Stage number 1. Collection of information about production technologies

The amount of information collected on production capabilities should be as complete as possible. Lack of data on any, even insignificant, at first glance, requirement, can lead to problems in the manufacture of the product or during its further operation.

Separately, you need to decide on the manufacturers of each unit and device details. If there is a restriction of choice, for example, the customer wants to perform all the work in their own production, then the developer should receive complete information about the technological capabilities and limitations of the production before starting the design.

Including it is worth paying attention to the timing of the development and production of elements of the device: take into account that a long design cycle can lead to the fact that the device loses its relevance. If the customer has his own workflow system, the device development contractor should also receive the necessary information about this system.

So, all the device parameters are defined, the manufacturer is found, the developer is selected.

Stage number 2. Calculation and coordination of the cost of the device

At the second stage it is necessary to calculate the cost of the product, which includes the costs of the following elements:

1. Electronic components (standard and specially designed)
2. All materials.
3. Development (work of engineers, designers, managers, etc.).
4. Production.
5. Assembly.
6. Overhead.

If the calculated cost satisfies the customer, the development process moves on. If the estimate does not fit into the project budget, then you have to go back to the very beginning and change any decisions made at the start.

Stage number 3. Start of device development

At the third stage, the development process itself begins. An important role is played by the launch of parallel processes. You must select the materials to be used in a particular production; decide on a specific list of components, taking into account the delivery time; choose the best automated technology at a price.

It happens that when creating devices the developer lays materials with redundant characteristics, while using complex and expensive technologies that can be completely replaced with classical ones, sacrificing additional time for design.

Of course, in some cases, complex technologies, such as HDI-design or flexible-rigid design of printed circuit boards, are dictated by the technical conditions. In such cases, the transition to simplified technologies is not beneficial, both in terms of development speed, and in terms of reliability and availability of the entire device. The developer should always take into account these points, because Without a conscious choice of a particular technology, the process of manufacturing a part or the entire device can be either prohibitively expensive or impossible in principle.

In parallel with the work of an engineer in the selection of materials and technologies, the work of a procurement specialist should take place. It identifies the suppliers of components and materials. All purchases must be guided by a compromise between the cost of a specific part and the time for its delivery.

It is advisable to connect as early as possible to the development process of a production support engineer. All sorts of preliminary estimates obtained from manufacturers of various parts and modules will greatly simplify and speed up the production of the designed product.

The interaction between all specialists in a team should be two-way, i.e. In the solution of any disputed issue, an optimal solution should be found. For example, if a systems engineer selects electronic components for a printed circuit board that only one available supplier can supply, this leads to additional risk, but it can be avoided by coordinating the replacement of specific components with their counterparts.

As a rule, a lot of specialists work within the project: engineers, programmers, designers, designers of body parts, etc. It is very important that they work as a well-coordinated team, this reduces the development time and the number of iterations. It is rather difficult to organize communication of all employees among themselves; this task should be taken over by the project manager, who also provides communication with the customer. Fast resolution of all issues arising during the design process is one of the fundamental factors that contribute to the successful completion of the entire project.

Stage number 4. Modeling and production setting

At the end of the design and passing the minimum set of checks (often checks are limited to the norm control) the project goes to production. If the development was simple, usually there is no difficulty. However, if the device is complex, for example, a miniature case and a board with high-speed interfaces, then it is not desirable to immediately transfer such a project to production. After all, solving problems that have arisen in production is much more complicated and expensive than envisaging them at the design stage. And to eliminate some errors is simply not possible. Therefore, after the end of development, various types of modeling are resorted to.

For example, if the device uses high-speed interfaces, conduct a simulation of the integrity of the signal. When using a complex case in the device (with connectors and additional details), a collection test is required. Also often becomes a problem of heat sink, which is solved by thermal modeling. In general, the greater the number of simulations that will be carried out before the transfer to production, the faster the customer will see his device ready for sale. Modeling is an additional investment of time and money, but it pays off at the production stage.

Thus, DFM is not a set of rigid rules, but principles for designing a device and managing a project as a whole, under which design ends as soon as possible and with minimal risks. The devices, created according to the principles of DFM, are easy to manufacture, maintainable as much as possible, and at the same time meet all the requirements for reliability and functional qualities. A set of specific measures varies depending on the task and other conditions. But the goal is always the same - to create a project for production.

Thanks for attention! For more information about the design of new devices can be found on the site Promwad team in the section " Stages of electronics development ."