All the layers will be stacked upon substrate.
The automatic optical inspection machine will detect any defects using laser and compare the digital image with Gerber file.Īt this stage all of the layers including the outer layer will be bonded together one upon each other. Layers ones placed and error occurred cannot be reversed. This machine will punch the holes accurately. The technician will place all layers in the machine known as “optical punch”.
This can be done by punching registration holes as mentioned in previous step. Process 5 #: Layer Alignment and Optical InspectionĪfter all the layers are ready from above mentioned steps, they are then aligned upon each other. This is achieved by washing off the PCB with another solvent. Now the hardened photo resist will be removed that protected the desired copper. The copper that is under the hardened photo resist will not be removed. Process 4 # : Removing the Unwanted CopperĪ powerful copper solvent solution is used to remove the excess copper just as alkaline solution removed the excess photo resist. If the board is two layers pcb then it will go for drilling otherwise for multilayer the more steps to come. The PCB now is available with resist covering the copper used to make tracks of circuit. The board is then washed with alkaline solution to remove excess photo resist. The clear area will pass the UV light thus hardening the excess photo resist which will be removed. The black ink on the photo film will block the UV light thus preventing the copper underneath it and not hardening the photo resist under the black ink traces. These photo film and photo resist film are settled on the laminate board by holding pins. It must be ensured that the photo films and photo resist films must match exactly upon each other. The photo resist is made of photo sensitive chemical which will harden when Ultra Violet radiation is applied. It must be ensured that no dust particle lie on the PCB otherwise it will cause circuit to short or open The decontaminated environment is very important to clean the PCB from copper laminate. The process involves removing away the copper to show up the design from the films. Laminate receives the copper that construct the PCB.pcb Substrate gives a strong platform for the PCB. The core material is epoxy resin and glass fiber known as substrate material. The basic structure of PCB is made of a laminate board. Now these photo films are printed on copper foil. Process 3 # : Inner layer printing: Photo resists and Copper The registration pins will fit in the registration holes. The films must have registration holes to sit accurately upon each other. This PCB alignment is achieved by adjusting the table on which the film sheets are fit, and after a small calibration of table the optimum alignment is attained. All these films must be aligned together to draw a PCB alignment. These films should be stored properly to avoid unnecessary contacts or fingerprints.Įach layer has its own film sheet. On the other hand, for outer layer, the black ink will be etched away and blank area is for copper. In case inner layer, the black ink represents the conductive copper track while the blank portion is non-conductive part. The plastic sheet come out from the plotter is the PCB printed with black ink. Plotters are very accurate in printing technology to give a highly detailed film of PCB design. These plotters will print circuit boards the films. The special printers used to print the PCB photo film is called “plotter”. The DFM (Design for Manufacturing) check is used to assure the minimum tolerance in PCB design. After the design is verified, it is sent to PCB fabrication house where a DFM check is performed.
This algorithm is run by the designer to check for any errors in the design.
The software has the user/designer defined algorithm that has key elements like track width, board edge spacing, trace and hole spacing and hole size. The extended Gerber delivers perfect output. The Gerber file is the 2D vector image file. The Gerber file is the standard file used by majority PCB fabricators to show the components of PCB layout like copper tracking layers, and solder mask etc. The most popular CAD PCB design software is Altium Designer, Eagle, ORCAD and Mentor PADS.Īfter the PCB design has been accepted for fabrication, the designer will generate a file from the design that is accepted by the PCB manufacturers. The designer must coordinate with the PCB manufacturer about the software used to layout the PCB design so that there will be no compatibility issues. The circuit designer draws schematics in CAD software that will be used to layout the PCB design.