A Quartz watch consists of :
A microprocessor chip, a pieces of capacitor (as a component to form the oscillation with the Quartz) a trimmer , a couple of resistor a coil for converting the timing signal into pulse to driver a few gears , a PCB board and a battery Cell.
Many people think that all Quartz watches look the same as the cost of a low cost Quartz movement can be as low as USD$2.00 now. For certain High quartz Swiss Quartz movement, the cost is much higher as the use better material and design. Rolex has the best design and likely the highest Cost of a Quartz movement, up to $300.
I have taken out two very old pieces of family watch Timex and Longines that have been using almost 30 years. There seems no difference between two watches as people judges Quartz base on price.
From outlook there is hard to tell the difference of the movement except the Longines is much thinner about 2.5mm whereas the Timex is about 8mm that tells you the difference in the cost already.
As The Timex has a much bigger engine, much bigger Coil, Bigger gears, and then much higher power consumption, this required a much bigger battery cell. Even though we can see the movement is made with a more complex process, every component is dispensed with a kind of industrial resin to hold the component in position, even onto the coil. Nowadays almost no one will dispense any glue, adhesive whatever on the PCB (Printed Circuit board) component.
Look at the Timex Microprocessor, it is using SC70 package, that is a package IC contain few more complex manufacturing process. It used 99.99% gold wire inside the chip.
That could be a high cost in the year 1986, nowadays almost no one uses Package IC for the microprocessor, they use COB (chip on board) just use some glue to stick the IC Chip
Onto the PCB, cure it and then use thin Aluminum Wire of 1.25 mil (1 mi is 1/1000”) diameter to connect the chip with the PCB, it is done by an Automatic Aluminum Wire bonder.
Note that Gold wire interconnect is much more reliable than Aluminum, whereas Aluminum wire is much cheaper in cost.
As for the Longines, we can see they use heavy plated PCB, battery contacts, even screws!
The Aluminum mechanical plate guilloched. There are 7 jewels. The PCB is face up with additional protection of the circuitry, and the coil is made with very fine wire.
Since they use 7 jewels, the movement as a much lighter friction, thus a smaller coil with thinner wire will be able to drive the circuit, this is a great power saving for the battery. Of course a smaller battery cell can do. So with all this design, the Longines is very thin. The Timex is very thick.
The Longines requires battery changes in 7 years, the Timex is about 2 years. Don’t forget these are made in 1986. When you buy a Swiss quartz watch, you may know they have made a lot of effort to ensure that the watch can be used for many years with very good timming accuracy.