Original subtitles

now I have a tres laminated on to a

copper clad board I'm going to mix an

etchant solution that when I put the

board into it will dissolve the copper

it will leave the copper underneath the

traces but if I leave it in too long it

will start to etch underneath as well so

I have to keep close eye on it

okay so I have this pyrex dish that I

need to make my bath in 200 milliliters

of water is enough to cover the circuit

board so I have a ratio from my bottle

of sodium per sulphate that says I

should mix 250 grams of sodium per

sulphate crystals with one liter of

water by multiplying that ratio by 200

times 10 to the negative 3 liters I get

50 grams so I need 50 grams of crystals

for my 200 milliliters of water

so here I have a bottle of sodium per

sulphate crystals a kitchen scale that

measures down to a gram and a coffee

filter as well as some latex gloves

so now I measure out 250 grams of sodium

per sulphate onto this coffee filter and

then I will add it to the liquid because

you add solid to water like you oughta

the reason for that is that the

splashing from the water will be

splashing acid all over the place and it

will be more concentrated than once

we've fully diluted it so we add the

acid to the water to prevent splashing

and possible damage to ourself for our

surroundings

once the sodium / sulfate is fully

dissolved we can add the circuit board

and let the magic of chemistry take over

it'll take anywhere from an hour to

several hours in order for it to fully

etch bearing in mind we need to keep a

close eye on it to make sure there's no

under etching

and now we have an etched PCB but we've

still got toner on the traces so we need

to remove the toner and we've got all

this etching left that I need to figure

out what to do with so let's look at

that this hi-tech container has the

spent etchant in it it's not useless I

can use it for another etch however it

does have a shelf life so if it's not

working when I use it later than I

dispose of it properly in accordance

with local laws and make a new batch so

I've cleaned the board off with soapy

water to get all the chemicals off and

now I'm rubbing the toner off of the

traces using a cotton ball soaked in

acetone acetone is just nail polish

remover you can get it from the cosmetic

section in your grocery store as you can

see it comes right off there are a few

little traces left on the PCB however

they're non conductive and they're not

interfering with the traces so it's not

going to be a problem in the circuit

and there you have it a nice shiny PCB

all I have to do is drill the vias no

the vias are the little holes

with a drill press the process is fairly

straightforward align the drill pull

down the handle and you have a hole

where you want it without a drill press

I would recommend using a hand drill not

a power drill that way you don't have

any vibrations or slipping or anything

happening that'll pull up a trace the

bits can be hard to come by you're not

going to find them at Lowe's or Home

Depot you'll have to go to someplace

more specialized Harbor Freight sells it

sets that come fairly small and they'll

work in a pinch however I would suggest

going to a electronic store or ordering

online for a set of bits that are

specifically designed for drilling vias

now that everything's drilled out and

ready I'm going to tinplate the traces

tinning the traces allows solder to

readily adhere to them as well as

protecting the copper traces from

corrosion and oxidation so it has

two-fold benefits it's not strictly

necessary but if you have liquid tin

there's really no reason not to do it

it's super easy and I think it's meet

the liquid tin does have diarrhea which

is a carcinogen so where your where your

gloves don't breathe it in be careful

when you're using it note that I have a

container labeled Science Bowl so that I

don't use it for anything else this is

not stuff to mess around with the

process is simple I just use a pipette

and put drops of the liquid tin directly

onto the traces and wait a few minutes

once it's finished then I just put the

liquid tin directly back into the

container and store it for later use as

with all the other chemicals I'm using

dispose in accordance with local state

and federal regulations I can't give you

specifics because one I won't be held

responsible for it and to hit varies

from area to area there are general

guidelines for neutralizing spend

solution on mg chemicals website once

the tinning is finished the PCB is ready

for components we'll show you how to lay

those out and solder them on in another

video thanks for watching