Willcom D4 Teardown: Design Influenced by Quanta

Aug 25, 2008
Nikkei Electronics Teardown Squad

This time, the game of the Nikkei Electronics Teardown Squad is Willcom Inc's Willcom D4, which is more of an ultrasmall Windows PC with a built-in PHS function than a mobile phone.

When we actually used it, we could see that Willcom gave priority to computer functions instead of communication capabilities. Probably, that is why the internal structure of the D4 resembles that of a PC.

The handset was developed by Sharp Corp. But the company seemingly outsourced its production to Quanta Computer Inc of Taiwan, which probably was deeply engaged in designing the hardware. The D4 differs greatly from other Sharp's handsets, such as the Internet Machine SoftBank 922SH and the Fullface2 SoftBank 921SH, for example, in the choice of components.

The existing products of Sharp are normally equipped with a self-manufactured 1seg tuner, but, in the D4, a 1seg tuner made by another maker is used. In addition, parts made by Taiwanese manufacturers are used everywhere.

On the whole, the D4 uses a large number of components, including many screws with different shapes. When we found a jumper wire on the board, we had the impression that the handset was designed in a short period of time.

The boards and other internal structures will be detailed in the following pages. Like our operations in the past, the disassembly was carried out with the cooperation of Fomalhaut Techno Solutions.マウス・ボタンタッチ・センサキーパッドの回路部分メイン基板と放熱機構

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ManufacturerSharp Corp
DimensionsApprox 188 x 84 x 25.9mm (including a dedicated battery, measured when closed, excluding projections)
WeightApprox 460g (including a dedicated battery)
Battery lifeApprox 1.5 hours (standard battery pack used, measured based on the JEITA Battery Run Time Measurement Method ver. 1.0)
Display5.0-inch (1024 x 600)
Memory cardmicroSD memory card
CameraEffective pixel count: 19.8 Mpixels (autofocus)
Battery7.4V, 960mAh


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When we opened the chassis on the keypad side, a heatsink covering the center portion of the mainboard drew our attention. It is probably used to transfer the heat generated from Intel Corp's Atom Z520 and the US15W chipset, which are arranged under the heatsink, to the area close to the vent hole.

A cooling fan, a 1.8-inch HDD and a battery storage space are located under the mainboard. The width of the D4 seems to be determined by the total width of these components.



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We discovered that the positions of individual parts, numbers, etc were printed on the mainboard. And It looked just like a computer board. There are many parts used on the mainboard including many LSIs made by Taiwanese manufactureres. The 1seg tuner module was probably made by RfStream Corp, not by Sharp.


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The Bluetooth transceiver IC and other parts were mounted on the board on the back side of the keypad circuitry. The LSI possibly related to the wireless LAN function was likely to be made by an affiliate of Quanta, which took charge of the production of the D4. As mentioned above, we found a jumper wire on this board, and it implied that the handset was designed in a short period of time.


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We also broke down the W-SIM card, which executes the PHS function. Spansion's flash memory, Oki Electric Industry Co Ltd's LSI, etc are inside the card.


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Next, we disassembled the touch sensor module, which is located on the right side of the LCD panel and used to move the mouse cursor on the screen. The module was probably manufactured by Synaptics Inc. The UTS6680 microcontroller, which is made by IdeaCom Technology Inc of Taiwan, was mounted on the sub-board to control the pen input device.


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Finally, we broke down the part that is located on the left side of the LCD display and acts as a mouse button. It is likely that the camera module mounted on the board in this block was not manufactured by Sharp. And Aveo Technology Corp's Aveo 301W is used as a camera controller LSI.