IEEC -Portable Data Storage -- When PC Cards Are Too Big

Portable Data Storage -- When PC Cards Are Too Big

Miniature Card

In 1989, the PCMCIA (Personal Computer Memory Card International Association) published their PC Card specifications, a set of guidelines for the physical and electrical specifications of the PC Card and corresponding socket. Three types of cards (Type I, II, and III) were eventually defined, all of the same width (54 mm) and length (85.6 mm), but with different thicknesses: Type I cards are 3.3 mm thick; Type II, 5 mm; and Type III, 10.5 mm. All cards use the same 68-pin connector.

PC Cards were targeted mostly at mobile computers, and the size of the cards was ideal for that application. Other systems are smaller than notebooks, however, and the size of the PC Card limits design flexibility and further system miniaturization. Examples of such systems include digital cameras, personal digital assistants, and voice recorders. It is these systems that drive the current search for a new, yet smaller, card form factor. Most of these applications only require a data storage solution -- usually flash memory -- to store images, text, or audio. Card-based processing power is seldom needed.

Six small form factor portable data storage cards are discussed below.

1. CompactFlash Cards

The CompactFlash Card design was first proposed by SanDisk in early 1995, and production started in late 1995. This (and the fact that SanDisk is the world's largest supplier of flash data storage products) has given CompactFlash a headstart compared to other cards.

2. Miniature Card

The Miniature Card format is supported by Intel and AMD (the leading flash memory manufacturers) as well some sixty other companies, including Compaq (PCs), Olympus (cameras), and Nokia (phones). Intel's Miniature Card is illustrated above.

3. SmartMedia Cards

Smart Media Cards, or SSFDC (Solid State Floppy Disk Cards) as they were known until recently, were developed by Toshiba and Samsung and are based on smart card technology. SmartMedia is currently backed by about sixty member companies -- mostly Japanese-based consumer electronics companies.

SmartMedia Card -The picture on the right is an x-ray of the die module. Note the wirebonds from the die to the traces which lead to plated-through holes.

4. MultiMedia Card

The MultiMedia Card was developed by Siemens. It is not yet in production, but Siemens is currently founding an association to support the MultiMedia Card format and hopes to start production before the end of 1997. Sampling is to start in September 1997.

5. Mega Storage Device

Panasonic recently announced the development of the Mega Storage Device, previously known in Japan as the SmallPC Card. It is targeted at digital cameras, personal digital assistants, and other portable devices.

6. NexFlash Serial Flash Module

Nexcom, a California company that has patented a novel flash memory technology, has developed a different memory card based on their flash technology. The Serial Flash Module is offered to Nexcom's customers as a packaging option. Most modules probably will be used in enclosed systems that use the module for upgrades or expansions.

Ultra Low Cost Packaging

It is too early to tell which format will be the preferred choice. Regardless of the outcome in the portable data storage market, the packaging approaches are interesting from a low cost packaging point of view. As the prices of the cards already suggest, the cost structures are quite different, and are driven by the following cost items:

Substrate -- The CompactFlash, Miniature, NexFlash and Mega Storage Device cards use FR4 printed circuit boards of various complexity and cost. Of lower cost are the SmartMedia Cards' thin, double-sided FR4 substrates that are manufactured in a reel-to-reel process and the leadframe that is used in the MultiMedia Card. In the future, Siemens plans to use a Molded Interconnection Device (MID) which would provide both the substrate and the card body, promising additional cost savings.

Connector -- The CompactFlash and Mega Storage Device cards use a pin and socket connector. The Miniature Card uses an elastomeric connector and the other cards use surface pads.

IC Packaging -- The SmartMedia and the MultiMedia cards achieve lower cost structures by wirebonding the bare memory die directly onto the respective substrates.

Card Assembly -- The CompactFlash, Miniature, and Mega Storage Device card constructions package a printed circuit board into a metal enclosure, a design that adds cost and complexity to he assembly process. The SmartMedia Card, on the other hand, uses a simple plastic card body into which the die module is glued. Perhaps even simpler, the body of the MultiMedia card is defined by over-molding the die assembly. NexFlash does not use any casing at all.

As electronics becomes ever more pervasive and penetrates products that were previously not considered electronics systems such as refrigerators, cameras, and parking tickets, there will develop a need for novel packaging technologies that do not follow the traditional component-on-board approach. With this in mind, perhaps the most interesting and successful packaging approach is the smart card, and it is not a coincidence that some of the lowest cost packaging technologies used in portable data storage products were borrowed from smart cards.

Some 700 million smart cards were manufactured in 1996, mostly in Europe where they are being used for an ever wider range of applications. A disposable pre-paid phone smart card can cost as little as $0.40 in high volumes. This includes:

A plastic card body, typically laminated or injection-molded and printed with graphics

A memory chip measuring up to 2 x 2 mm, 5-6 I/O wirebonded and encapsulated

A die module substrate consisting of a single-sided FR4 tape with gold-plated contact pads

Some smart card constructions even eliminate the die module substrate by implanting the die upside-down (quasi-flip chip) directly into the plastic card body and printing the external contact pads with conductive paste.

The opportunities in electronics are boundless. Please call a Partner at Prismark Partners.

Copyright 1997 Integrated Electronics Engineering Center and Prismark Partners LLC.

09/97

Warranty Disclaimer -- All information used in the preparation of this report was obtained from sources believed to be reliable at the time the information was collected. Prismark Partners LLC, its employees, its agents, and assignees have exercised their best efforts in preparing this report. Prismark Partners LLC extends no warranties with respect to this information and shall bear no liability whatsoever to the report recipient or to any other party as a result of the use of this report or the information contained herein.