$12.99 for 10pieces PCB 5x5cm

5x5cm

PCB prototype $12.99 for 10pcs.  

you can send your gerber file to  pcb@hqenet.com or alicebrain1992@gmail.com 

I will quote for you as soon as possible in 24hours.

we can talk online.my skype: hqew-four

Plating

Next HQEW will introduce electroplate the boards with copper.  The operator loads the panels onto the flight bars.  He checks all the clamps to ensure a good electrical connection.  The panels themselves act as cathodes for electroplating and we can plate the hole walls thanks to the conductive carbon layer already deposited there.  The operator starts the automated plating line.  The copper surface of the panels is cleaned and activated in a number of baths and then electroplated.  .  The whole process is computer controlled to ensure that each set or flight of panels stays in each bath exactly the right amount of time.  You can see the copper anodes in their bags.

To ensure good conductivity through the holes we need to plate an average of 25 microns of copper on the hole walls.  This means that we also plate 25 – 30 microns on the surface tracks.  So if we start with a typical 17.5 micron copper foil it will be 40 – 42 microns after processing.

The baths are designed to produce an even copper thickness across the panel.  Modern chemical solutions also have good “throwing power” to produce an even thickness of copper right through the hole.

Once we have plated the copper onto the board we then plate a thin layer of tin.  This we will use in the next step of the process when we etch off the unwanted copper foil.

When plating is completed the flight of panels is returned to the operator and he unloads and stacks the plated panels.  He then uses non-destructive testing to check a sample of each flight to ensure that the copper and tin plating is the correct thickness.

Image the outer layers.

Hello,we are HQEW PCB...We image the outer layers in a clean room to make sure that no dust gets onto the panel surface where it could cause a short or open circuit on the finished PCB.

The panel is first coated with a layer of photosensitive film, the photoresist, which is hot-rolled onto the copper using a cut-sheet laminator. The laminated panels are collected by an automatic rack. The clean room uses yellow lighting as the photoresist is sensitive to UV light.

The bed of the printer has registration pins matching the holes in the phototools and the panel. The operator loads the first film onto the pins, then the laminated panel and finally the second film. The pins ensure that the top and bottom layers are precisely aligned. The printer uses powerful UV lamps to harden the photoresist. So the photomask is clear where we want the resist to harden and black where we don’t want resist.

The Mylar film which protected the photoresist is now removed and the imaged panel is conveyored out of the clean room and through a developer which removes the unhardened resist. For inner layers the copper pattern we want was covered by the resist. For outer layers it is exposed ready to be plated. The operator now checks the panels to make sure that the copper surface is clean and all the unwanted resist has been removed.

Electroless copper deposition

The first step in the plating process is the chemical deposition of a very thin layer of copper on the hole walls.  The operator clamps the production panels into the jigs.  The line is fully computer controlled and the panels are carried through a series of chemical and rinsing baths by the overhead crane.  Almost all PCBs with 2 or more copper layers use plated through holes to connect the conductors between the layers.  A good connection needs about 25 microns of copper on the walls of the holes.  This thickness must be electroplated, but the walls of the holes are non-conductive glass cloth and resin.  So the first step is to deposit a conductive layer over the hole walls.  We use electroless copper, that is we deposit chemically a layer of copper about 1 micron thick over the walls of the hole (and incidentally across the whole panel).  This is a multi-stage process as you see from the video with washing steps between the stages.  We pre-treat the panel, then we seed the hole wall with micro-particles of palladium, and finally deposit the copper

Alice skype: hqew-four

Drilling the PCB

Drilling printed circuit boards

X-ray drill of reference holes

Now we drill the holes for leaded components and the via holes that link the copper layers together.  First we use an X-ray drill to locate  targets in the copper of the inner layers.  The machine drills registration holes to ensure that we will drill precisely through the centre of the inner layer pads.

Prepare the stacks for drillng

To set up the drill the operator first puts a panel of exit material on the drill bed.  This stops the drill tearing the copper foil as it comes through the PCB.  Then he loads one or more PCB panels, and a sheet of aluminium entry foil.

Drilling the holes

The drilling machine is computer-controlled. The operator selects the right drill program.  This tells the machine which drill to use and the X Y co-ordinates of the holes.  Our drills use air-driven spindles which can rotate up to 150,000 revolutions per minute.  High speed drilling ensures clean hole walls to provide a secure base for good plating on the hole walls.

Drilling is a slow process as each hole must be drilled individually.  So depending on the drill size we drill a stack of one to three PCB panels together.  We can drill holes down to 100 microns in diameter.  To give you an idea of the size, the diameter of a human hair is about 150 microns.  Drill change is fully automatic.  The machine selects the drill to use from the drill rack, checks that it is the correct size, and then loads it into the drill head.

Once all the holes are drilled the operator unloads the panels from the drilling machine and discards the entry and exit material.

http://www.aliexpress.com/store/432347

Cut-off excess resin

During bonding excess resin from the prepreg is squeezed to the edge of the panel outside the image area.  This excess is now cut off on a computer controlled profiling machine.  The operator loads the panel onto the bed of the machine and selects the correct program with the X y co-ordinates of the path for the cutter to follow.  The drilling machine uses the points of the drill but the profiling machine uses the specially patterned shank of the tool. The cutter mills out the final profile for the production panel.  The drilled panel is now ready for plating.

PCB manufacture step by step:Double-sided PCB

First ,make the gerber file to be PCB production data.

The board designer has prepared his layout on a Computer Aided Design or CAD system.  Each CAD system uses its own internal data format, so the PCB industry has developed a standard output format to transfer the layout data to the manufacturer.  This is Extended Gerber or RS274X.  The Gerber files define the copper tracking layers (4 in the job we are following) as well as the soldermasks and component notations.

First we check that data meets our manufacturing requirements.  These checks are mostly done automatically.  We check the track widths, the space between tracks, the pads around the holes, the smallest hole size etc.  The engineer can also check and measure individual areas where he wishes.  Once the data is verified as good he will output all the tool files needed to drive the machines that will make and test the PCB.

PCB manufacture in China :Alice 

skype: hqew-four

The scrolling LED strip(2)

As you can see from that video, column are lit in a batch, but one row at a time. When done really slowly you can't make out the whole letter. When sped up, persistence of vision makes it appear that they are all on at once.

Detail from the reverse side:




Keypad driver



One slightly puzzling aspect was the absence of any extra chips for the 55-key keypad, as all 10 chips had now been accounted for. There were 8 wires leading to it (on a ribbon cable) on the left, in the photo, and 7 wires on the right. This led to a deduction that this was a 7 x 8 key keypad matrix. Since that would give 56 possible keys, it seemed very likely.

A close inspection of the cable on the left showed 8 x 10k pull-up resistors for that cable, plus each of the 8 wires were connected directly to the CPU. On the other side, the "row driver" chip was also connected to the 7-wire cable going to the keypad.

Thus it seems that the design was that the row driver would be repeatedly activated for one row at a time (driving it low) which would source current for the LEDs via the transistors which invert the signal, plus at the same time sink current for the keypad (the keypad does not go via the transistors). The pull-up resistors would raise the input to the CPU high, except if a key was pressed. Thus the CPU could deduce which key was being pressed, while it was also outputting to the LEDs.





Taking control!



Knowing how the 595 works, it seemed reasonable to assume that if I could disconnect the clock, data, and latch signals from the processor, and supply my own, then I could make the LEDs show whatever I wanted.

After a considerable amount of time tracing PCB traces, I worked out that it was very easy to do, because each of those reached the processor chip via a jumper on the front.

To do this cut the three jumpers indicated and then solder wires onto the circled ends of the now-cut link (that is the part furthest from the processor).



Now the processor thinks it is sending data to the 595 chips, but it isn't.

Those three wires (clock, data, latch) are then connected to the Arduino as shown (pin numbers for a Uno or similar). You also need to connect the ground wire as well, I took it from the electrolytic capacitor nearby as shown.

This photo shows it displaying the main sketch. The letters are blurred because of the time taken to take the photo:



This shows the connection between the Uno and the LED device. (It is actually a Ruggeduino because I was worried I might blow something up during testing).



As you can see, only four wires are needed between the Arduino and the display. The display was independently powered because of the power required to drive all the LEDs.


Schematic



A partial schematic is below. It doesn't show all the 595 chips, nor all of the LEDs, transistors, keyboard interface etc. However the main points which show the LED multiplexing are there:





Demonstration video







Completed project



After researching all the above I turned my sign (for the time being) into a temperature and humidity display.

Example display:







I made up an freestanding "Arduino-like" board using the Evil Mad Scientist Atmega target board. This was bolted to the inside of the battery compartment. The battery holder had been discarded because the batteries had leaked and corroded it.




Opening the door to the compartment you can see the board in place with five wires running into the connection points on the LED strip (the four wires described earlier, plus a connection to the +3.3v Vcc line to power the processor).




The board with the various parts shown in detail:



The wiring and relevant code were taken from the temperature and humidity sensor project described here:
http://alicebrain.blogspot.com/2013/12/temperature-and-humidity-sensor-battery.html

My skype :hqew-four