Die banking -
The concept of banking is not new, people have been using it in various forms for centuries. Yet the ideology behind banking still services the same basic need whether the product may be gold bullion or semiconductor die.
Why bank die?
1. Security
2. Confidence in the banker’s ability to manage and store your product appropriately
3. Easy release of product when you need it
4. Preservation of product against deterioration.
Although it could be said that the electronics industry is generally fast moving and innovative on closer look you find that certain sectors of this industry develop a lot faster than others. Many factors, the main one being financial pressure, can result in electrical components becoming obsolete despite the fact there may still be some kind of consumer demand for the parts. A good example would be to compare a military product using an old technology which may have a required lifespan of 30 years in contrast to the latest Intel processor which almost becomes obsolete the moment it hits the commercial shelves! This disparity in the electrical component supply chain poses a great problem to the manufacturer trying to continue building a project where the parts designed for it are slowly becoming obsolete. Semiconductor life cycles are also becoming shorter as the demand for Fab capacity increases, this is why Die banking holds great appeal and offers cost effective long term security for a project which otherwise may need a complete re-design.
In order for Die banking to work effectively three things need to happen, the customer needs to be informed with up to date product obsolescence information, the die banker needs to make the necessary ´Last time buys´ required to stock enough product to service the lifetime of the project and lastly the product needs to be managed and stored appropriately in order to guarantee yield and maintain quality. The expertise needed to monitor storage conditions and pick the appropriate carrier for the product is developed over a long period of time. Just as you wouldn´t hand over your life savings to a gambler you wouldn´t hand valuable and irreplaceable die product to those with no silicon handling or storage experience!
Maintaining precise traceability is vital to die banking, product needs to be quickly identified and prepared for shipment when required. Just as you would expect a bank balance from an ATM the customer can easily access their inventory levels and call-off product at any time. Having a comprehensive knowledge of all die supply forms, their associated carriers and next operation in the assembly process ensures full product support and gives the customer confidence that their die will meet the requirements of their specification.
Many other products deteriorate over time and inherently so does their quality. Bare die are particularly sensitive in this area, and need to be stored in meticulously controlled conditions. Due to their metal composition, bare die need to be excluded from contact with air to prevent oxidisation on the die. Also die need to be carefully protected from ESD as without taking the proper precautions the electrical quality of the product can deteriorate over time. Die Technology are leading experts in die storage and can offer to store your product for you.
Die banking is traditionally viewed as a means of prolonging the necessary supply of a product to suit a project. However die banking can also be viewed as a tool for servicing finished products even after the project is complete. A good example is to take a plastic packaged part in a finished product. Assuming the limited lifespan of a plastic part what happens to the end product when this component fails and no further plastic package product is available? Another possible die banking solution is to store ´spares´ so that in effect a ´new´ replacement package can be produced and allow the finished product to continue operating. It is much safer to store bare silicon for long periods than silicon in plastic packages as the plastic leaches out unwanted contaminants over time and these can effect the operation of the semiconductor. Furthermore using an identical ´mother´ die to build a replacement package assures compatibility with the equipment it´s designed into. Conversely, a newer ´alternative´ may demonstrate less tolerance to Radiation effects, or be less tolerant to the noisy power or data sources of the older equipment. We can assemble the packaging solution in-house and provide consultation where needed.
Die Banking - The Process
Obsolescence notification The project on acceptance receives a component review to determine other potential obsolescence issues which may develop through out its lifespan. Close liaison with franchised die manufacturers allows for immediate customer notification of any relevant parts going obsolete.
Last Time Buys
The total purchases are made preferably through a franchised supplier as this assures support directly from fab to the assembly process. Over the lifetime of the project the cost saved in terms of inflation and also the discount for a one-off bulk buy far outweighs the immediate expense. In direct comparison with stocking packaged parts, die storage could be viewed as inexpensive as it doesn´t include the upfront costs of package, assembly and test.
Storage
Product is stored in either the carrier chosen by customer specification or whatever is deemed most suitable for the product type. The carrier is then stored in the correct environment. Full-computerised traceability is maintained and when product is called for delivery it is then processed in accordance with either customer specification or the typical standard product flow and prepared for shipment in the supply form required by the customer. At this point both physical and electrical testing can be performed on the product if required as an additional confirmation of reliability and overall quality. Finally shipment occurs in the supply form required by the customer.
Die Banking - Capabilities
Product can be stored in special containers which are smoke and water resistant
Product can be stored for many years
Customers own product can be held
Product can be stored in customers own dedicated dry nitrogen store
Additional testing can be performed to guarantee reliability and product quality at product release
Generic parts can be manufactured into packaged product through other assembly manufacturers
Availability of a critical strategic silicon bank in UK/Europe in the event of conflict or a trade war
We can assure product homogeneity by holding stock of a single diffusion run
Co-ordination of group activity for collective die banking across several projects to reduce overall costs.
