Emerald Group Publishing Limited
Copyright © 2000, MCB UP Limited
EM&T/OnBoard Seminars 1999 - another successful year, come on 2000!
EM&T/OnBoard Seminars 1999 - another successful year, come on 2000!
For the fourth year running the seminars sponsored by Electronic Manufacturing and Test were a great success with hundreds of people attending the sessions over the two days of the OnBoard Show. Lead free soldering was undoubtedly the subject of the event but each session drew a large number of delegates to the capital. "The seminars are the most popular in the industry", commented Bob Willis, OnBoard Seminar coordinator. We even ran out of magazines to give to visitors, it was that busy!
Now let's review what issues were raised by speakers at the EM&T seminars. If you want a copy of any of the papers then just fax the relevant speaker direct for a copy of his presentation quoting the EM&T Seminars at OnBoard 1999.
OnBoard Seminar 1999 topics Day one 15 September
"Design and manufacturing high density printed boards" - Steve Carr, ACB
The printed circuit board can be an extremely complex structure but through close co-operation between design, manufacture and assembly its production can be simplified. That was the essence of Steve Carr's presentation, during which at OnBoard he was able to illustrate the type of complex circuits and how design issues can affect the price and yield. He indicated the increasing use of blind and berried via technology and how advanced circuits must use modern fabrication techniques to make products feasible.
The circuit board today is a complex feat of engineering co-operation between supplier and customer and you cannot expect to produce a product without a meaningful partnership.
"Zero defect solder paste printing" - Alan Hobby, DEK Printing Machines
The screen printing basics were covered along with the criteria for paste deposits. Alan highlighted the most common reasons for faults and stated that poor printing is most often linked to poor education or attention to the quality of the printed board and its design. Alan Hobby is one of the most respected process engineers associated with printing technology, a practical presenter who demonstrated the real reasons for poor paste printing. If each of the visitors to the show implemented some of the advice given, printing defects could, for those companies, be a thing of the past.
"Machine capability exposed" - Peter Grundy, Chéne Limited
Peter Grundy, in his customary dynamic manner, illustrated the selection process for making sure equipment is capable of producing today's demanding ultra complex products. Fresh from setting-up the manufacturing facilities of ChÁne it had again focused his mind on the need to pay attention to detail.
Peter focused on the cost of mistakes, illustrating that as the volume of rework goes up it is not directly proportional to its cost. The costs of getting things wrong is much higher than most people estimate, particularly with the increased miniaturisation. Peter showed that 0201 chips are here and 01005 are not that far away and may need to be used as a reference when selection of new equipment is being considered. Peter is always available through ChÁne to assist engineers to select and specify new equipment. "Simultaneous double sided reflow soldering (SDSRS)" - Bob Willis, EPS
The SMART Group Charity Reports have so far raised over £3,500 for charities in the UK and USA and one of the latest reports covers SDSRS. This was the first opportunity to see and hear how you can solder both sides of a complex surface mount assembly in one reflow operation. SDSRS eliminates one reflow process, increases the reliability of joints, reduces process time and saves the cost of capital equipment and floor space. During the presentation, each part of the process was explained with video footage to show the process in action. A further source of process information is the online presentation available on www.bobwillis.co.uk
"Flip chip, chip on board assembly and material requirements" - Peter Swanson, Intertronics
Flip chip and chip on board are technologies of interest to most engineers. They make portable products feasible, was the focus of Peter Swanson's presentation. Peter illustrated examples of products before outlining the different applications for encapsulants and their physical requirements. He then explained the methods of cure before detailing different material types like epoxies, silicones, urethanes and possible issues relating to their use.
Finally Peter compared the different types of underfill materials for flip chip assembly, illustrating the main trends for future chip assembly. Throughout the presentation, Peter provided possible failure modes and how correct cooperation between supplier and design engineer can achieve a reliable product. Intertronics also offers all the IPC range of standards, which do cover certain aspects of these technologies.
"A practical guide to using X-ray inspection" - Steve Hursey, X-Tek Systems
Although X-ray inspection techniques have been available for many years ball grid array and flip chip solder joint inspection has created a demand for this inspection technique in a greater number of manufacturing facilities. During the presentation Steve Hursey illustrated the basics in the use of X-ray, covering the process, equipment manufacture and of course allayed any concern over health and safety. He then continued with presenting some of the images and defects which can be easily found with X-ray, concentrating on BGA inspection.
X-Tech have over the last couple of years built up a considerable knowledge base on inspection through their own inspection service. This allows customers to have products tested with photographs to illustrate any faults which they may have during soldering.
Day two 16 September
"Lead free soldering overview" - Brian Richards, National Physical Laboratory
This presentation was actually made by Carl Levoguer, but further information on the NPL projects can be obtained from Brian Richards, who is heading up the NPL project teams. Carl and Brian helped to produce the DTI Lead Free Soldering Report and The Worlds First Interactive Lead Free Soldering Cook Book CD-ROM also available from NPL.
In his presentation Carl outlined the current draft legislation, the material options and the current state of various projects which are being undertaken worldwide. He illustrated that process changes are quite feasible; it just needs work by process engineers to develop a plan for lead free implementation. Inspection standards, component compatibility for higher process temperatures and education are the areas which need urgent action. Carl also illustrated the content and findings of the Lead Free Report which is currently available from the NPL.
"A guide to lead free wave and reflow soldering" - Roger Bilham, RB Consultancy
The second lead free presentation of the day, but there was no less interest in the subject as Roger's audience was sitting and standing in the aisles to hear the presentation. Roger explained the driving forces of the move to lead free and covered some of the existing projects that are being undertaken. He also highlighted the work that still needs to be done to prove the long-term reliability of products. During his talk he indicated the cost of lead free solders, illustrating that bar price as a percentage would increase far more than paste prices.
He felt that the although there are process issues it was the components which may provide the biggest hurdle to the implementation. The move to a greener process was, however, achievable as he was currently assisting customers in their implementation plans. Currently the alloy of choice for reflow is likely to be Sn-Ag-Cu and for wave it may be Sn-Ag-Cu(-Sb). The future will tell and there are a lot more topics to be considered in future seminars.
"Design and assembly of plastic three dimensional boards" - Russ Wood, Apiec Limited
Plastic three-dimensional circuit boards have been around for many years but most engineering and design staff have never seen the concept in practice. There are many applications in the consumer and automotive industry that we use every day and don't even know.
Russ Wood explained the basics of materials, the process of manufacture and the advantages of plastic two- and three-dimensional products. With the increasing realisation of the effects on higher temperatures of lead free soldering, the higher temperature capability of this type of circuit could be a distinct advantage, suggests Mr Wood.
"The hidden cost of sub-contract" - Lawrence Faulkner, Prism Electronics
Lawrence first introduced Prism as a contract manufacturer, his views on the market and the increasing use of this type of service across the world. During the presentation he summarised each section with practical hints, which generated a lot of smiles from the audience. "We have all been there before" was the unspoken thought of the delegates who crammed into every seat.
A partnership is a two-way street, not just what is good for one of the partners. Communication through different disciplines in manufacture is critical and above all honesty in all aspects is key to success.
In summary, Lawrence expressed the true story of contracting, the advantages, disadvantages and where the hidden cost of contracting should be understood during outsourcing. A very valuable presentation from an entertaining speaker.
"Automatic optical inspection for SMT" - Sean O'Neil, CMS Systems Limited
The use of automatic inspection is growing simply due to the fact that the density of modern circuits prevents manual inspection. With over 1,000 terminations or paste deposits on most products it is simply not feasible to check each location. It has been realised that in process control is the way forward to zero defect manufacture, so let the machine take the strain!
During his presentation Sean O'Neil listed the key features which could be used as a check list for selecting a machine supplier. Indicating the through-put speed is often the issue most engineers focus on but stating the capability and repeatability of the machine system is most important. Then an increasing realisation the some form of in-line verification process is beneficial but often difficult for engineers to justify. Hopefully, by reviewing this paper more people will have the knowledge to implement process control.
"Selection and use of temperature profiling equipment" - Mike Hayward, ECD Europe
Temperature profiling of printed board assemblies to monitor and adjust a reflow soldering facility has been a standard technique used in professional companies for many years. Monitoring surface and component temperature can be misunderstood, as are the methods of thermocouple attachment. Each issue was explained by Mike Hayward, emphasising that if you don't know how to profile, ask! In fact ECD has assisted in the production on an interactive reflow CD-ROM for customers to get the most useful information during profiling.
Alternative techniques are being developed to monitor the process of reflow soldering rather than just measuring board surface temperatures, as this can in some cases be misleading. The move is to monitor the process after a profile has been established as this can detect equipment changes which often are the true causes of faults. A good and informative presentation which provided food for thought; do we monitor the product or do we control the process?
For further information on each of the technical papers fax the speakers direct on their office fax numbers requesting a copy of the EM&T/OnBoard Seminar papers. Also find out how to present a paper at OnBoard or find out what is planned for 2000 at www.onboard.co.uk
Peter Grundy - Chene; Fax: +44 (0) 1420 471309. Alan Hobby - DEK Printing Machines; Fax: +44 (0) 1305 760123. Steve Hursey - X-Tek Systems; Fax: +44 (0) 1442 828118. Peter Swanson - Intertronics; Fax: +44 (0) 1865 842172. Steve Carr - ACB; Fax: +44 (0) 1420 471309. Brian Richards - NPL; Fax: +44 (0) 181 943 7160. Roger Bilham - RB Consultancy; Fax: +44 (0) 8700 548613. Russ Wood - Apiec Limited; Fax: +44 (0) 1995 604170. Lawrence Faulkner - Prism Electronics; Fax: +44 (0) 1480 494047. Sean O'Neil - CMS Systems Limited; Fax: (353) 1 8368556; Mike Hayward - ECD Europe; Fax: +44 (0) 1633 861013.