M/s. ELTEK CIRCUITS, Ghaziabad
Date & Duration (Days) : 21/10/2019 (08 Hrs.) (2nd Year students)
Number of Student Participants : 52
Number of Faculty Participants * : 02
Benefit in terms of learning/Skill/Knowledge obtained *
The industrial visit to the ELTEK CIRCUITS single layer and double layer printed circuit boards design and manufacturing facilities have been highly educational helping in learning and providing an insight into the modern PCB design & manufacturing as per the customer requirements.
High-End PCB Manufacturing
The substrate most commonly used in printed circuit boards
is a glass fiber reinforced (fiberglass) epoxy resin with a copper foil bonded on to one or both sides.
Printed circuit boards
are typically made with copper. Depending on the requirements, the copper is plated to a substrate and carved away to expose the design of the board. Since there are multiple layers, they must be lined up and bonded together for a secure fit.
Session plan/Brochure/Document/overall report of the activity
PCB Manufacturing Process Steps
Step 1: Design and Output
Circuit boards should be rigorously compatible with, a PCB layout created by the designer using PCB design software. Commonly-used PCB design software includes Altium Designer, OrCAD, Pads, KiCad, Eagle etc.
Step 2: From File to Film
PCB printing begins after designers output the PCB schematic files and manufacturers conduct a DFM check. Manufacturers use a special printer called a plotter, which makes photo films of the PCBs, to print circuit boards. Manufacturers will use the films to image the PCBs.
Step 3: Printing the Inner layers: Where Will the Copper Go?
The creation of films in previous step aims to map out copper path. Now it's time to print the figure on the film onto a copper foil.
This step in PCB manufacturing prepares to make actual PCB. The basic form of PCB comprises a laminate board whose core material is epoxy resin and glass fiber that are also called substrate material.
The film and board line up and receive a blast of UV light. The light passes through the clear parts of the film, hardening the photo resist on the copper underneath. The black ink from the plotter prevents the light from reaching the areas not meant to harden, and they are slated for removal.
After the board becomes prepared, it is washed with an alkaline solution that removes any photo resist left unhardened. A final pressure wash removes anything else left on the surface. The board is then dried.
Step 4: Removing the Unwanted Copper
With the photo resist removed and the hardened resist covering the copper we wish to keep, the board proceeds to the next stage: unwanted copper removal. Just as the alkaline solution removed the resist, a more powerful chemical preparation eats away the excess copper. The copper solvent solution bath removes all of the exposed copper. Meanwhile, the desired copper remains fully protected beneath the hardened layer of photo resist.
Step 5: Layer Alignment and Optical Inspection
With all the layers clean and ready, the layers require alignment punches to ensure they all line up. The registration holes align the inner layers to the outer ones. The technician places the layers into a machine called the optical punch, which permits an exact correspondence so the registration holes are accurately punched.
Step 6: Layer-up and Bond
In this stage, the circuit board takes shape. All the separate layers await their union. With the layers ready and confirmed, they simply need to fuse together. Outer layers must join with the substrate. The process happens in two steps: layer-up and bonding.
Step 7: Drill
Finally, holes are bored into the stack board. All components slated to come later, such as copper-linking via holes and leaded aspects, rely on the exactness of precision drill holes.
Step 8: Plating and Copper Deposition
After drilling, the panel moves onto plating. The process fuses the different layers together using chemical deposition. After a thorough cleaning, the panel undergoes a series of chemical baths. During the baths, a chemical deposition process deposits a thin layer " about one micron thick " of copper over the surface of the panel. The copper goes into the recently drilled holes.
Step 9: Outer Layer Imaging
We image the outer layers of the panel with PCB design. We begin with the layers in a sterile room to prevent any contaminants from sticking to the layer surface, then apply a layer of photo resist to the panel. The prepped panel passes into the yellow room. UV lights affect photo resist. Yellow light wavelengths don't carry UV levels sufficient to affect the photo resist.
Step 10: Plating
We return to the plating room. Electroplate the panel with a thin layer of copper. The exposed sections of the panel from the outer layer photo resist stage receive the copper electro-plating.
Step 11: Final Etching
The tin protects the desired copper during this stage. The unwanted exposed copper and copper beneath the remaining resist layer undergo removal.
Step 12: Solder Mask Application
Before the solder mask is applied to both sides of the board, the panels are cleaned and covered with an epoxy solder mask ink. The boards receive a blast of UV light, which passes through a solder mask photo film. The covered portions remain unhardened and will undergo removal.
Step 13: Electrical Test
As a final precaution, a technician performs electrical tests on the PCB. The automated procedure confirms the functionality of the PCB and its conformity to the original design.