Making PWB

When assembling an electronic circuit, a board is needed on which the components can be mounted and wired together.
Mainly, I use the universal prined wiring board (PWB) for assembling the circuit. But I will explain about instruments that makes the printed board.
When you make the high frequency circuit, you need to consider the wiring length and the route of wiring etc.
Therefore when you make the high frequency circuit ( radio, high speed CPU etc. ), you need to make the printed wiring board.
In other countries, they are refered to as "Printed Circuit Boards," or PCBs.

The printed board is doing the structure which stuck copper leaf on insulation board such as the epoxy material of glass or the epoxy material of paper or the material of bakelite. The copper leaf becomes a wiring part. There are 2 kinds of types in the printed board. They are single-sided printed board and double sided printed board.
To make the printed wiring board, leaving the necessary(wiring part) place of the copper leaf, the unnecessary(insulate part) place is lost. This work is called Etching

There are several method to make the printed board.
Fundamentally the copper leaf is melted with the solution of the Ferric Chloride. The mask pattern is used to leave the wiring part.
You can write the mask pattern directly on negative printed board with oily ink. Some ink is melted by solvent, then you had better to check beforehand.
Even this method is good in the case that you make only 1 sheet.

This time, I will introduce the method using positive exposure printed board as negative printed board.
The sensitizer has been applied on negative printed board. The nature of the sensitizer when hit the light changes. Lighted part of sensitizer can melt to the developer and the part not lighted does not melt.
The mask is made with the black color ink where the part that you want to leave the copper leaf. ( positive mask )

Dissolve the copper leaf is called Etching.

Positive exposure printed board

The photograph left is the positive exposure printed board. The board is put in the bag for the shading.
When it hits to the sunshine, the nature of sensitizer changes.
It is different from the sensitive paper of the photograph and in a little light, it doesn't change.
You do not need to handle to a nervous temperament.

There are several kinds of size of the board. Then you choose board close to the device that you make.
It can even to cut and use that board and decide large. It needs to cut it so as not to hit to light much. It is serious a little bit.
The size is about 150 mm x 100 mm to 300 mm x 200 mm.
Even the kind of the insulation board there is the epoxy material of glass or the epoxy material of paper.
The epoxy material of paper is cheap, but durability of it is bad a little. There is not a problem where I used.

Photograph central under is the development medicine of a sensitizer.
The development material is used with dissolving in hot water.

The pink colored bag of the photograph right is transparent film. The mask pattern is written to this film with the lettering tape or ink.
I depict the pattern to the preparation of the block copy with the PC and print it with the printer.

Ultraviolet ray exposure equipment

The ultraviolet ray is used when baking the print pattern on the positive exposure printed board.
This equipment uses the ultraviolet rays which go out of the fluorescence light.
It takes about 20 minutes for baking, so, this equipment has the timer circuit.
I made this equipment by myself.
For the details, refer to "the ultraviolet ray exposure equipment".

Resist pen

This is the oily dry ink to use for the repair of the mask pattern.
Depending on the kind of the dry ink, there is one which has been dissolved in the etchant. So, you had better to check beforehand.
With this pen, the direct mask pattern can be pictured, too.

Clamp

This is an instrument that sticks and fixes the mask pattern and the positive exposure printed board.
The part that is seen black is made of the sponge.
Piling up the mask pattern and the positive exposure printed board to the sponge and holds down and fixes with glass.

Etching apparatus

This is an instrument that melts the unnecessary copper leaf of printed board.
Without using this instrument, you can make with the etching liquid that inserted in a palette.
To melt well it is the hang to do as the new etching liquid touches the printed board and agitate a few of the printed board.
This instrument does and gives the temperature adjustment of liquid and agitation of etching liquid automatically.
You can see an air pump on the left. It is the same as the one that sends air to tank of tropical fish.
Connecting this to the agitator tank with the vinyl pipe. Air blows out from under of the agitator tank and agitate liquid.
The heater is attached on the right side of the agitator tank. As the temperature of liquid becomes regular with the thermostat.
As for the temperature of liquid, 40°C to 43°C is appropriate and don't exceed absolutely over 45°C.
The stick form thermometer is attached on the left side of the agitator tank. The temperature of liquid is monitored with this.
The cover of the agitator tank has small holes for vacating.
The printed board is suspended from the cover by using the titanium wire.
After the temperature of liquid is adjusted, the printed board for etching is suspended from the cover.
Sometimes, you need lift up the board from liquid to confirme the condition.

Quartz pipe heater

The temperature control of etching liquid is done with this heater.
The knob is attached for adjustment temperature at the upper part.
There is a small neon electric bulb in the glass pipe. This bulb light up during operation( Temperature rising ).
You can confirm that it became setting temperature, because it disappears when it becomes setting temperature.

Etching liquid

This is the solution of the Ferric Chloride(FeCl₃·H₂O).
The Ferric Chloride is not the toxic substance, play thing, dangerous article that were regulated with the laws but the liquid that the copper of the printed board dissolved by the etching becomes a waste fluid regulation object.(in case of Japan)
Even if it is a little it pours to sewerage and also do not bury during the soil. Processing medicine that is attached to etching liquid without fail is used or it must process it in the waste fluid processing place of the specialty.
When liquid is attached to the clothes it is never able to take it.
Do the attention to handling sufficiently, because the clothes have changed color. ( My experiences )

Avoid contact with eyes.
If it enters to the eye it needs to wash away sufficiently with water right away.

Resist solvent

This solvent is used to remove the mask pattern of the printed board that the etching was ended.

Battery driven mini drill

This is a mini drill that makes holes for mounting the parts on the printed board.

For most of parts like resistor, cpacitor, the size of hole is about 0.6 mm.

Flux

The copper foil after removing the sensitizer becomes clean, but sheet copper is becoming bare condition then oxidization begins right away. Flux needs to be applied thinly to prevent oxidization.
When flux is applied, you can make the copper leaf in clean condition forever. Also, you can carry out soldering easily.

Solder resist ( Generally, it doesn't use.)

When you see the printed board that is used for electronic devices etc. the wiring face( face that does soldering ) is doing green.
This is because solsder resist is applying it. Solsder resist applies to the part that is unnecessary to attach solder. The color is doing green.
For the use of industries solder is attached with the machine. It guards it with solder resist so as not to use useless solder.
There is not a necessity in the case that soldering is done with hand work.