PCB Manufacturing Process
Learn PCB Manufacturing Process Explained in Detail with Flowchart and Video.
PCB Manufacturing Process a very difficult and complex. Here we will learn and understand the process with the help of Flowchart and Video.
Different Types of PCB
- Single Sided PCB or Single Layer PCB
- Double Sided PCB or Double Layer PCB
- Multilayer PCB
- Rigid PCB
- Flex PCB or Flexible PCB
- Rigid-Flex PCB or Rigid-Flexible PCB
PCB Manufacturing Process Flowchart
PCB Assembly Process Flowchart
PCB Manufacturing Process Flowchart – Step by Step
Step-1: Patterning or Etching
Majority of printed circuit boards are manufactured by applying a layer of copper over the entire surface of the PCB substrate material either on one side or both sides. This creates a blank printed circuit board, with the copper everywhere on the surface. From here the unwanted copper is removed by subtractive methods.
Step-2: Photoengraving
The photoengraving process uses a mask or photomask combined with chemical etching to subtract or remove the copper areas from the circuit board substrate.
The photomask is created with a photoplotter which takes the design from a CAD PCB software. Lower resolution photomasks are sometimes created with the use of a laser printer using a transparency.
Step-3: Lamination
Many printed circuit boards are made up of multiple layers; these are referred to as multi-layer printed circuit boards. They consist of several thin etched boards or trace layers and are bonded together through the process of lamination.
Step-4: Drilling
Each layer of the printed circuit board requires the ability of one layer to connect to another, this is done through drilling small holes called “VIAS“. These drilled holes require precision placement and are most commonly done with the use of an automated drilling machine. These machines are driven by computer programs and files called numerically controlled drill or NCD files also referred to as excellon files. These files determine the position and size of each drill in the design.
Controlled depth drilling can be used to drill just one layer of the circuit board rather than drilling through all the layers. This can be accomplished by drilling the individual sheets or layers of the PCB prior to lamination.
- Blind Vias: When the holes connect a layer to the outside surface
- Buried Vias: When the holes only connect interior layers and not to the outside surface.
The walls of each hole (for multi-layer boards) are copper plated to form plated-through holes that connect the conductive layers of the printed circuit board.
Step-5: Solder Plating (Solder Resist)
Pads and lands which will require electronic components to be mounted on are plated to allow solderability of the components. Bare copper is not readily solderable and requires the surface to be plated with a material that facilitates soldering. In the past a lead based tin was used to plate the surfaces, but with RoHS (Restriction of Hazardous Substances) compliance enacted newer materials are being used such as nickel and gold to both offer solderability and comply with RoHS standards.
Areas that should not be solderable are covered with a material to resist soldering. Solder resist refers the a polymer coating that acts as a solder mask and prevents solder from bridging traces and possibly creating short circuits to nearby component leads.
Step-6: Silk Screen
When visible information needs to be applied to the board such as company logos, part numbers or instructions, silk screening is used to apply the text to the outer surface of the circuit board. Where spacing allows, screened text can indicate component designators, switch setting requirements and additional features to assist in the PCB assembly process.
PS: “Red Print” refers to the silk screening of a one sided printed circuit board.
Step-7: Testing
Unassembled circuit boards are subjected to a bare board test where each circuit connection is verified as correct on the finished circuit board. In high volume circuit board production, a bed of nails tester or fixture is used to make contact with the copper lands or holes on one or both sides of the board to facilitate testing. Computers are used to control the electrical testing unit to send a small current through each contact point on the bed of nails and verify that such current can be detected on the appropriate contact points.
For small to medium volume production runs, a flying probe tester is used to check electrical contacts. These flying probes employ moving heads to make contact with the copper lands and holes to validate the electrical connectivity of the board being tested.
Printed Circuit Board Manufacturing Process (Step by Step Tutorial)
PCB Manufacturing and Assembly Services
If you are looking for a Reliable and Trustworthy one-stop destination of PCB fabrication and assembly, they you can go with PCBWay.
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The company offers – PCB Prototype, Custom PCB Design and Manufacturing, Advanced PCB Manufacturing, SMD-Stencil and PCB Assembly Services. They can also help you Procure Electronic Components.
Read: Lead-Free Soldering: A Safer Approach to PCB Assembly
FAQs: Printed Circuit Board Manufacturing Process
What is the PCB manufacturing process?
The PCB manufacturing process involves several key steps:
- Design: Creating a schematic layout of the desired circuit.
- Substrate Preparation: Preparing the base material (typically fiberglass or composite) and applying a copper layer.
- Etching: Using chemical processes to remove excess copper, leaving only the desired circuit pattern.
- Drilling: Making holes for component placement and vias.
- Plating: Adding a thin layer of metal to the walls of the holes.
- Solder Mask Application: Applying a protective layer over the copper traces, leaving only the solder pads exposed.
- Component Placement: Mounting electronic components onto the board.
- Soldering: Connecting the components to the copper traces using solder.
- Testing: Verifying the functionality and connectivity of the board.
- Finishing: Applying a final coating to protect the PCB from environmental factors.
What are the types of PCBs?
There are various types of PCBs based on their complexity and intended use:
- Single-Sided PCB: Components are on one side, with traces on the other.
- Double-Sided PCB: Components and traces on both sides, connected by vias.
- Multi-Layer PCB: Contains multiple layers of copper and insulating material, suitable for complex circuits.
- Rigid PCB: Standard PCB made from rigid materials.
- Flexible PCB: Made from flexible materials, suitable for bendable applications.
- Rigid-Flex PCB: Combines rigid and flexible sections, ideal for complex form factors.
What are the common materials used in PCB manufacturing?
The primary materials used in PCB manufacturing include:
- Substrate Material: Usually fiberglass-reinforced epoxy (FR-4) for rigid boards, and polyimide for flexible boards.
- Conductive Layer: Copper is the most common metal used for conductive traces.
- Solder Mask: Protective layer usually made of epoxy, applied to prevent solder bridges and oxidation.
- Silkscreen: A layer containing component labels, indicators, and other information.
- Vias and Pads: Typically made of copper with various surface finishes to improve solderability and durability.
What is the significance of PCB testing?
PCB testing is crucial to ensure the functionality and reliability of electronic devices. Testing helps:
- Detect Defects: Identifying manufacturing errors like short circuits, open circuits, and misaligned components.
- Ensure Quality: Verifying the board's electrical performance and adherence to design specifications.
- Prevent Failures: Identifying potential points of failure that could lead to malfunction or damage.
- Save Costs: Detecting and rectifying issues early reduces waste and the need for costly rework.
- Optimize Performance: Testing helps fine-tune the design and manufacturing process for better overall performance.
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