IEEC - Motorola Gold Line Pen Pager

Motorola Gold Line Pen Pager

Motorola Gold Line Pen Pager

Paging Basics

A pager is a dedicated RF (radio frequency) device that allows the carrier of the pager to receive messages broadcast on a specific frequency over a special network of radio base stations. In order to page someone, the caller dials into a paging terminal and records a numeric or alphanumeric message, often with operator assistance. The paging terminal converts the message into a pager code, and relays it to all base stations (i.e., transmitters) within the pager's coverage area. The coverage area may be local, regional or national, depending on the service the carrier of the pager is subscribing to.

All base stations within the coverage area simultaneously broadcast ("simulcast") the pager code on a particular frequency. This frequency will vary depending on the standard and service provider used -- Motorola's pen pager works in the 900 MHz range. Base stations typically broadcast with 300 to 500 watts and speeds of up to 6400 bps.

The code is received by every pager within the coverage area which is tuned to that particular frequency. However, only the pager whose address code matches that contained in the pager code will be alerted and will display the message.

For an in-depth discussion of pagers and other wireless communications technologies, please contact Prismark Partners LLC, at (631) 367-9187.

Pager Market

The first pager-like system was used in 1921 by the Detroit Police Department. However, the first pager that we would today recognize as such was Motorola's Pageboy I, introduced in 1974. It had no display, nor could it store messages, but it fulfilled all the main functions of a pager and was portable.

By 1980, there were 3.2 million subscribers of paging services worldwide, but these were predominantly on-site users, such as doctors in a hospital. The pager would work only within the vicinity of the base station located on the grounds of the hospital. By 1990, wide-area paging had been introduced and the subscriber base topped 22 million worldwide.

In 1994, there were over 61 million subscribers worldwide. Pagers had become popular not only with business users, but also with personal users in developed countries. Furthermore, pagers had become a popular alternative to the inadeqaute telephone systems in developing countries. Over three million pagers are sold annually in China, for example.

By the end of the decade, Prismark Partners expects the paging market to grow to over 200 million subscribers. This means that three percent of the entire world population will be using pagers.

Motorola Gold Line Pen Pager

Motorola is a pioneer in paging technologies and commands almost two-thirds of the worldwide market for paging devices. The Gold Line pen pager, featured in this report, is a twelve-digit numeric pager which is functionally equivalent to the standard form factor Bravo pager (which clips to the belt). It is shaped like a marker pen, however, and measures only 5.25"x0.75"x0.5". Motorola is targeting the pen pager at the "upscale executive and professional", who would wear this pager in his or her shirt pocket. It retails for $199 in the US.

Overall Construction

The pen pager is enclosed in a plastic housing, consisting of a front and back cover, as well as a lid for the single AA battery compartment (see photo on previous page). The inside of the front cover contains a small vibrating device used for silent alerting of a received message (Motorola's Vibra-Page). The front cover also contains the button contacts to the switch located on the printed circuit board. This switch allows the user to scroll through messages.

The pager contains two printed circuit boards: The main printed circuit board runs along the entire length of the pen pager, except for a cut-out for the battery compartment. The second printed circuit board is mounted onto the main board, but is only 1.3" long. It is not visible on the above photo because during the assembly of the pager the LCD module is folded over and on top of the second PCB.

Main Printed Circuit Board Assembly

The main printed circuit board is a four layer FR4 construction measuring 3.94"x0.59" and is 30 mil thick. Minimum linewidth and spaces are 8 mil each, with minimum plated through hole diameters of 14 mil. The entire board is gold plated. Surface mount components are mounted on both sides of the main board: There is one integrated circuit on each of the top and bottom sides, as well as a total of 121 passive components. Minimum component pitch is 20 mil for a 48 lead PQFP device.

Daughter Printed Circuit Board Assembly

The daughter board is mounted onto the main printed circuit board and in turn connects to the LCD module via a heat seal connector. The two boards are joined with eutectic tin-lead solder, as are all the solder joints on both boards. The daughter board measures 1.3"x0.59" and is also a 30 mil thick, four layer FR4 construction. Minimum linewidth is only 3.5 mil and minimum line spaces measure 6 mil. These specifications are so tight because a flip chip device is mounted onto the daughter board. This flip chip device is the driver for the LCD module, and the photo above shows the conductor traces fanning out from the driver to the contacts of the heat seal connector. The board is gold-plated.

Flip Chip LCD Driver

The LCD driver is a flip chip device mounted onto the daughter board. X-rays show that the die has a staggered peripheral bump pattern with approximately 75-85 bumps of standard C4 construction. The bumps have a diameter of approximately 8-10 mil, and the pitch is approximately 0.5 mm between two bumps on the same row, and 0.3 mm between two rows. The photo below is a cross section of the flip chip, as well as the main and daughter boards. It shows that the bumped flip chip (two bumps are visible) is completely underfilled with an encapsulant believed to be Hysol. The four light- colored columns crossing the daughter board are plated-through holes located just behind the surface of the cross section.

Cross Section of Flip Chip and Printed Circuit Boards

Summary

The Motorola Gold Line pen pager is a well-packaged system that makes excellent use of the limited space available in a portable communications product.

The Gold Line pen pager is functionally roughly equivalent to the standard form factor Bravo pager. To package the same functions into a considerably smaller envelope, Motorola has used a more complex substrate (higher layercount, finer features) and advanced semiconductor packaging.

This is the first use of flip chip on a printed circuit board that we have seen in any Motorola product. It illustrates what we expect to be an increasing use of flip chips in portable communications products.

The overall design is well thought out, and the assembly appears neat an clean.

Please contact Prismark Partners LLC, or the Integrated Electronics Engineering Center (IEEC) at Binghamton University to discuss the opportunities and challenges wireless communications technologies present to your business.

Warranty Disclaimer -- All information in the preparation of these reports was obtained from sources believed to be reliable at the time the information was collected. Prismark Partners LLC, its employees, its agents, and assigns have exercised their best efforts in preparing these reports. 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 these reports or the information contained herein.

Copyright 1996 Integrated Electronics Engineering Center and Prismark Partners LLC.

1/96