Etching Process

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Etching Process

What is Etching?is traditionally the process of using strongacidormordantto cut into the unprotected parts of ametalsurface to create a design inincised in the metal.

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a selective removal of material from the surface of a PCB by means of the chemical action of an etchant (or etching agent). Etching usually removes the copper areas which are not desired on the finished PCB.

What is Incised?mark or decorate (an object or surface) with a cut or a series of cuts.

In traditional pure etching, a metal (usually copper, zinc or steel) plate is covered with a waxygroundwhich is resistant to acid.

Etching bygoldsmithsand other metal-workers in order to decorate metal items such as guns, armor, cups and plates has been known in Europe since theMiddle Agesat least, and may go back to antiquity.

Daniel Hopfer(circa 14701536) of Augsburg, Germany. Hopfer was a craftsman who decorated armor in this way, and applied the method to printmaking, using iron plates (many of which still exist)

Basic Ways of Etching

Mechanical EtchingIt involves the use of a machine tool and a special cutter to remove a narrow strip of copper from the boundary of each pad and trace this electrically isolates the circuit element from the rest of the foil

Examples of Mechanical Etching

CNC Milling Machine

What is CNC Milling MachineIt is a specific form of computer numerical controlled (CNC) machining. Milling itself is a machining process similar to both drilling and cutting, and able to achieve many of the operations performed by cutting and drilling machines.

Like drilling, milling uses a rotating cylindrical cutting tool. However, the cutter in a milling machine is able to move along multiple axes, and can create a variety of shapes, slots and holes.

Materials and Tools needed for Engraving Operation

The Working FixtureThe work surface of your CNC mill should be as level as possible since a deviation of as little as .001 could be the difference between properly engraving a board and barely scratching it.

The spindle or router that will be used to mill your boards should be used to level the work surface with an appropriate end mill. Additionally the fixture should have a means of holding down the workpiece.

Examples of Working Fixtures

Tooling (Engraving)to mark or ornament with incised letters, designs, etc.

Tooling (Drill Bit)are cutting tools used to remove material to create holes, almost always of circular cross-section.

Tooling (Endmill)is a type ofmilling cutter, acutting toolused in industrialmillingapplications. It is distinguished from thedrill bitin its application, geometry, and manufacture.

While a drill bit can only cut in the axial direction, a milling bit can generally cut in all directions, though some cannot cut axially.

Copper CladIt is a raw material for making PCB. It is the main need in etching process.

Handtools

CNC Milling Command CodesIn order to engrave paths in the copper clad boards, the cnc Milling Machine requires software like Eagle CAD, PCB- Probe, ZEN Toolworks to plan the movements of tool in the miling machine.

Chemical Etchingrelies on the action of a corrosive liquid to dissolve away unwanted copper in order to define the desired circuit

Materials and Equipments Needed in Chemical Etching Process

Ferric ChlorideItis an industrial scale commoditychemical compound, with the formulaFeCl3

The primary use of ferric chloride is to remove impurities in water and for wastewater treatment. The second-largest application is in the production of printed circuit boards (PCBs).

Ferric Chloride

Be careful !!

Ammonium persulfate (APS)It is theinorganic compoundwith the formula (NH4)2S2O8. It is a colourless (white) salt that is highly soluble in water, much more so than the related potassium salt.

It is a strongoxidizing agentthat is used inpolymer chemistry, as anetchant, and as a cleaning andbleaching agent.

Be careful !!

Video (10 Types of Etchants)

SpongeIt is used to dry up the copper clad after removing the cleaning process.

WaterIt is used to remove the excess Etchants in the copper clad after quenching process.

Rubber GlovesIt is used to protect the hands from the hazards of chemicals during etching process.

PCB/Copper Clad

Process in chemical etching

Wear PPEWear Personal Protective Equipment before doing the dangerous task. It is very important to ensure the health of the worker before working.

PlanPlan the needed materials, Etching Paths, Circuits, and the etching process ( If the operator wants to use permanent pen, masking tape and printed etching paths).Clean the Copper Clad before quenching it to the Etchants

Methods of EtchingThe use of Masking Tape is to cover the needed paths for the continuity of electricity.The use of Permanent Pen to draw the etching paths after putting the PCB in etchant. Use the white board marker to erase the permanent pen.

The use of software to draw the etching paths.

QuenchingAfter planning the etching paths, quench the PCB in the Etchant such as ferric chloride or an other type of etchants.After quenching in the enchant carefully remove the PCB in the etchants and rinse it with clean water to remove the excess etchant.

Finish product

First, plan the needed components for the Series Circuit such as Resistor, wire, LED, Copper Clad, Cuter and the schematic drawing.Put the masking tape or permanent pen in the copper clad in the area that you want to protect from the corrosion of acid.

ResistorLEDLEDLED

ResistorLEDLEDLED

ResistorLEDLEDLED

Masking tape or Permanent Pen

After covering the desired paths, quench the copper clad in the ferric chloride to produce a PCB.After quenching the Copper clad in the etchants wash the PCB to remove the excess acid in the board. ( PLEASE WEAR YOUR PPE)

After the quenching of the PCB , drill the PCB for the assembly of the components.Solder the components in the PCB.