What the Inside of a Phone looks like

(Nokia 2140 Construction Kit)

Picture

The following photographs show the internal construction of a Nokia 2140 (the original Orange Nokia).  My thanks to Chris Conwell of Mobiles in Watford for kindly donating the subject of the photographs.  Most phones have the same basic layout with considerable shielding surrounding and separating the digital and RF components.

General Layout

General Layout

The phone comprises the case; a flexible PCB on which is mounted the display and keyboard; a rigid multi layer PCB containing the processor and RF circuitry and two RF shields, one made of metalised plastic and one of magnesium alloy.

Flexible Display PCB

Flexible PCB

The flexible PCB (only the front is shown - the back is even more boring) holds the keyboard and display as well as the SIM holder.  The veritical bar to the right of the SIM holder and covered with white plastic is the on/off and volume controls.  When in the case the SIM holder wraps around the rigid PCB to position the volume switches at the side of the case. The earpice and microphone are mounted on very fragile sections of the flexible PCB and are very easily damaged when removing and refitting the case (take note those who want to change your case for one of a different colour!)

Rigid PCB

The Rigid PCB

This printed circuit board houses most of the RF and digital electronics.  On the right of this photograph the two grey lines running up the right hand edge of the PCB are rigid co-ax feeders for the antenna. 

 

Rigid PCB

This is the other side of the main rigid PCB.  The upper section houses the Radio Frequency components and the lower the digital bits.  The large capacitor is to help smooth the short duration peaks of high current drawn by a digital phone.

Tuned ccts

At 1800MHz a tuned circuit which comprises inductance and capacitance can have the inductive component formed from no more than a couple of bends in a wire. 

This enlarged photo of the top right hand corner of the rigid PCB shows RF tuned circuits where the "coil" is formed by the PCB tracks themselves.  The larger three contact black rectangles are transistors, the smaller 2 contact ones are capacitors and resistors.

The two white components just to the right and above the words "RF Transformer" are small coils made from about 3 turns of wire on a ceramic former.