Andy Richards looks at the challenges facing mobile phone manufacturers in test.

Technology moves almost as fast as fashion, and this is particularly true in the production environment. Today, the expectation is that high quality can be delivered at a low price and although much work has been done over the years to design in reliability, the requirement to prove the product through test remains. Testing of course takes time and the high volumes of modern manufacture have the effect of magnifying seemingly minute time gains or losses into very significant sums of money.
The mobile telephone is perhaps the best example of how technology and fashion have collided. In recent years, the explosion in demand for handsets has adjusted the equation, which, for handset manufacturers, determines profit and loss. Developing cutting edge designs and bringing on new technologies costs significant sums of money but as volumes rise the production environment becomes critical.
The introduction of third generation (3G) handsets using leading edge technologies such as WCDMA has brought this issue into even sharper focus. The reason for this is that, at first, geographical coverage of 3G services will be on a smaller scale than the current GSM services and so it is vital that 3G handsets can also support the existing GSM services.
Even worse for manufacturers, handsets must be able to access both networks at once. This is in order that the handset can 'hand-over' from one service to another, as the handset moves in and out of the coverage areas. The result of this is that the testing requirements are multiplied each time another technology is added and this means longer and more expensive test times for manufacturers.
In this environment, the selection of a test equipment supplier for the production test application will sometimes depend upon the ability to deliver only small advantages in test time. These advantages are magnified by volume production but at other times the development of test solutions, based upon new technologies, can result in very significant advantages.
So, which approaches are the most successful in delivering effective test in the shortest possible time? Significant advantages can be made through closer partnership with both the handset developer and the production group. Some handset manufacturers retain production facilities in house and others prefer to contract out to a specialist.
Anritsu, a global test and measurement supplier and Flextronics, a company specialising in developing production test solutions and also a provider of large-scale production facilities for mobile handsets, has recently announced a partnership in this area. Flextronics are recognised as having great expertise in the field of volume manufacturing, with Flextronics Test having over thirty years experience in Test System integration and development, this coupled with Anritsu's knowledge of test enables both sides to leverage on each others expertise. So exactly how can such a partnership deliver an advantage to the industry?
Closer working relationships between test equipment manufacturers and production specialists can result in a number of benefits, most of which come from the increased level of trust. In the more normal 'customer/supplier' relationship, companies are often more reluctant to share a longer-term view, in a competitive situation, because of the need to safeguard vital IPR from the eyes of the competition. However, the benefits of a closer working relationship and sharing of road maps can be very significant because the longer term view allows earlier involvement of the test equipment manufacturer in understanding the test requirements, including 'design for test' considerations.

Firstly, closer working permits a much better capture of requirements to take place, much earlier than is otherwise possible. This can affect all aspects of the design of the test equipment but also the design of the device under test. Building in special test modes can significantly reduce testing times for a number of reasons, particularly in the mobile environment. In order to make the necessary measurements relating to the handsets ability to transmit and receive information, it must first be in a transmit/receive mode. This process of course takes time and time is the enemy in this case, so one answer is to build special test modes into the handset, that allow the handset to get itself into the necessary mode without the need for an external network. If this can be done in advance of the device reaching the testing station then the time saving can be very significant.
In addition, testing is not limited to straightforward testing of the functionality of the product. In a highly developed production environment the manufacture, alignment and test of the product are co-ordinated in 'closed loop' manor, to allow the production team to observe the effect of component selection and device alignment. Trends can be observed which can indicate the tendency of the devices being manufactured and adjusted, to move outside of the production tolerances, well in advance of this actually happening. It can also assist in replacing individual alignment with a different approach, whereby all the devices can be set to a mean value, which through observation during the testing phase, can be determined to be likely to place the overwhelming majority of the devices being tested within the acceptable band. As component values drift (itself a result of someone else's production process) the effect can be observed and adjustments to the process are made to correct it.
Sometimes the relationship between functionality and testing can be seemingly even less directly connected, with the identification of trends, which may indicate increased failure in the field, later in the life cycle of the product. Only very detailed analysis of field failure information and the establishment of a very tightly controlled production environment can make such prediction possible and specific enough to be used as a tool during manufacture, but the advantages to customer satisfaction and warranty costs are well worth the additional effort.
Further integration between the handset design and the test equipment design can result in even greater savings, through the synchronisation of testing phases. The aim in this respect is, as far as possible, to reduce the interaction between the handset and the tester. The reason for this is that "hand shaking" activities are inefficient because they limit the speed of the overall process to the speed of the slowest participant. A much faster result is achieved when the handset can simply run unguided through a series of predetermined test conditions, which are then "observed" by the test equipment and the necessary measurements recorded.

Interaction is however desirable, at critical points of the set-up process. This point comes when the test equipment instructs the handset to adjust itself in order to correct errors observed by the tester. These intelligent processes enable greater use of lower tolerance components, with commensurate cost savings.
These types of improvements can only be achieved through closer co-ordination. With early involvement in the design and industrialisation processes, the test equipment manufacturer, handset designer and industrialisation team can work together to develop products with the shortest possible test time. The benefits are shared by all, in the form of lower cost and more reliable products. The benefits for those directly involved have the potential to be even greater, but these higher rewards can only be realised through the cultivation of an environment of trust, working together in close partnership.