When it comes to PCB manufacturing, assembly, and design, there are certain standards to follow. It is crucial that industries and organization set specific standards for their activities. Standards are what help us to achieve success in whatever field we find ourselves. Regardless of the industry you are, it is of utmost importance to adhere to the standards set out in that industry.
Furthermore, it is important to opt for an electronic contract manufacturer that adheres to IPC standards for PCB assembly and design. There are several standards in the PCB and electronics industry. However, the IPC standard stands out. Also, this standard covers every process in PCB manufacturing. The functionality and reliability of your PCB design depend on the ability of your electronic contract manufacturer to work with IPC standards.
Also, the IPC standard is a recognized and acceptable standards in the electronic and PCB manufacturing industry. It is often referred to as the basis on which PCB design recommendations are established. There are several IPC standards. However, our major focus in this article is the IPC 2221A standard.
What are IPC standards?
IPC is an abbreviation that refers to the Institute for Printed Circuits. It is an official name for the association that designs PCB-related standards. In addition, the IPC standard is an acceptable and recognized standard for PCB design, electronic assembly, and PCB manufacturing. In 1998, the official name for the IPC changed to Association Connecting Electronics Industries. However, it is still commonly called IPC to date.
Also, the IPC standards create the basis for assembly, design, packaging, and inspection requirements for the electronics industry. IPC standards set out standard that serve as a guideline for PCB fabrication, design, test, and assembly. Also, these standards can determine the failure or success of a product if PCB designers comply with them.
There are several factors in PCB design that can impact the manufacturability and reliability of a circuit board. For instance, PCB designers can guess the perfect side of pad for THT components. Therefore, designing without compliance with the IPC standards might result in non-conformance of uniformity between manufacturers and designers.
There are different IPC standards for PCB design layout. These include IPC 2221, IPC 221A, IPC 2222, and IPC 2223. The IPC standards are the most widely acceptable standards in the electronics industry. Also, IPC establishes standards for the electronics industry. Therefore, it plays a significant role in PCB manufacturing. Furthermore, IPC standards are crucial for every stage of PCB manufacturing.
What is the IPC 2221A Standard?
Our major focus is the IPC 2221A standard. The IPC 2221A standard creates generic requirements for Organic PCB design and other forms of interconnecting structures. Also, the organic materials may be integrated or reinforced with inorganic materials. IPC 2221A is a guideline for the process of PCB design. This standard addresses topics like design layout, materials, and parts lists.
Also, it is a reference document that has been revised on several occasions. The specific standards stated in this document helps to determine all aspects of PCB design. Also, this document offers the structure for interconnecting electromechanical, mechanical, and electronic components.
Furthermore, the IPC 2221A a crucial standard that covers almost every aspect of PCB design. This standard creates the generic requirements for PCB designs. Selecting materials for a PCB and designing its physical features requires balancing the mechanical, thermal, and electrical performance. Also, it requires balancing the cost, manufacturing and cost of a circuit board.
What Issues Does the IPC 2221A Standard Address?
The IPC 2221A covers a large area of PCB design. Also, it talks about the most important considerations for PCB design.
Design layout
According to the IPC 2221A standard, the layout process should include a design review of layout information. The layout approval will ensure that the manufacturing-related factors were fully considered in the design. Also, there are several interrelated considerations that determine performance of an interconnecting structure design.
As regards end-product usage, it crucial to consider the impact of the following parameters on the design:
- Installation interface that impact the location and size of connector, mounting holes, and the placement of parts and brackets.
- Equipment environmental conditions like heat produced by the components, shock, and vibration, ambient temperature, and ventilation.
- Manufacturing limitations like minimum plating thickness, board shape, minimum etched features, etc.
- Type of assembly technology used; through hole, surface mount, and mixed.
Parts list
A parts list in a PCB design refers to the tabulation of materials and parts utilized in the construction of PCBA. Also, the list will include all end item identifiable materials and parts. The materials excluded are those used in the manufacturing process. However, many include specifications pertinent to the assembly manufacturer and reference to the logic diagram.
Electronic components like resistors, transistors, fuses, etc will have reference designators. Electrical reference designators assignment shall be similar to the assignments given to similar components on the logic diagram. Group similar items like capacitors, resistors, and ICs in numerical or ascending order.
Test requirement considerations
Before starting a PCB design, there should be a testability review meeting with fabrication and testing. Also, testability concerns like circuit controllability, circuit visibility, and test requirements should be discussed as an aspect of a test strategy.
Material Selection for IPC 2221A Standard
There is a wide range of materials a PCB designer can select from. Also, these materials range from standard to specialized, and highly sophisticated. Therefore, during material specifications, the designer needs to determine the requirements of the PCB application. This means that the PCB designer must understand the requirements the circuit board must meet.
Furthermore, these requirements include interconnections, circuit density, electrical properties, etc. Also, highly sophisticated materials will require increased processing and material costs. When designing a composite from materials having varying temperature characteristics, the greatest end-use temperature allowed must be restricted to the lowest rated material.
Other requirements like thermal stability, resin formula, and flame resistance may be crucial when comparing various materials.
Properties to consider when choosing materials for PCB
Structural strength
When selecting laminate, you need to define the service requirements the material must need. Service requirements like shock, vibration, and environment. The laminate choice should comprise standard materials to prevent time consuming and costly tasks. Also, the choice of laminates should maintain the best balance of properties.
Materials should be available in the size and form required. Special materials can be costly and have longer lead times.
Environmental properties
The environmental properties of common dielectric materials included glass transition temperature, flexural modulus, and tensile strength.
Electrical properties
Some crucial properties to look out for include moisture resistance, electrical strength, hydrolytic stability, and dielectric constant. You can consult the manufacturer of the laminate for specific values.
Materials Recommended by IPC 2221A Standards
Epoxies
Epoxy resin is known as a versatile adhesive for mechanical and insulating bonding applications. This material provides various electrical and physical properties like chemical resistance, thermal vacuum stability, and cohesive strengths. Also, epoxy resin comes with several cure methods and time. furthermore, epoxies are available with various fillers, reinforcements, and modifiers.
Conductive materials
Metallic coatings determine the creation of conductive pattern. This specific plating provides additional benefits like long term solderability, corrosion prevention, and wear resistance. The IPC standards provide integrity and thickness requirements for metallic coatings and platings.
Organic protective coatings
According to IPC 2221A standard, markings and coating must be compatible with each other and other parts in the PCB and PCBA. The utilization of solder resist coatings must be according to the requirements of the IPC. The dielectric properties of solder resist can maintain electrical integrity when solder resist function as an electrical insulator.
Semiconductive coatings
Semi Conductive coatings function as a conductive starter coating before electrolytic copper plating. These coatings are usually applied to the hole. Therefore, the coating should be of good quality to ensure subsequent metallic deposition. Tin and palladium are materials commonly used for these coatings. Also, the PCB manufacturer deposits a thin layer on exposed surfaces, particularly the drilled holes. Therefore, this offers a surface to auto-catalyze the deposition of electroless copper.
Considerations for Power Distribution in PCB Design
A crucial factor that requires great consideration in PCB design is power distribution. Also, the grounding scheme can serve as part of the distribution system. The grounding scheme offer both DC power return and AC reference plane. Consider the following for power distribution in PCB design:
- Use enough decoupling capacitance to decouple the power distribution at the PCB connector. Also, distribute enough power/ground decoupling capacitors throughout the areas of the logic device board.
- Ensure you maintain a low RF impedance throughout the distribution of the DC power. Also, a ground that is not properly designed can lead to RF emissions.
- Keep capacitor leads very short and place them adjacent to the crucial circuit to reduce the radiation and impedance loop of the coupling capacitor.
- Use planes for ground and power distribution. This is a good way to distribute grounds and power in a multilayer PCB is to integrate planes. It is advisable to make the ground signals and incoming power to terminate before connecting to the internal planes.
- Run power traces very close to ground planes when utilizing power conductors. Both ground and power traces should be wide enough. The ground and power planes should would become one plane.
- Design the power and grounding first in digital power distribution schemes. Also, route all interfacing to a single reference edge. Avoid opposing end interconnections. If you can’t avoid them, be careful when routing ground and power away from active PCBs.
- All ground structures should be heavy enough at the interconnection reference edge.
- Use the shortest conductor length between devices. Also, PCBs should be in separate areas for low, medium, and high frequency circuits.
IPC 2221A Guidelines for Designing PCB Assemblies
Consider the following guidelines when designing circuit board assemblies
- Identify the correct polarity of the component when possible
- Ensure you identify transistor base and collector properly
- Keep grounding planes or buses apart from each other when using different grounds
- Analog design should consider signal conductors and ground conductor connections last
- Ensure heat-radiating and heat-sensitive are kept as far away as possible. Also, you can integrate heatsinks when necessary.
Benefits of Complying With IPC 2221A Standards in PCB Design
IPC 2221A standards play a crucial role in printed circuit board design. Manufacturing reliable and functional PCB products requires careful attention to detail. Also, commitment to quality is necessary throughout the manufacturing process.
With several standards for PCB design and assembly, you can integrate the IPC 2221A standard for almost all stages of production. PCB companies must adhere to the IPC standards to achieve high-quality PCBs that meet the requirements of customers. Below are the benefits of complying with the IPC 2221A standard.
Improved PCB design quality
The IPC 2221A standard creates generic requirements for Organic PCB design and other forms of interconnecting structures. When these standards are severely adhered to, a PCB designer will achieve high quality PCB design. Also, the guidelines of this standard focus on creating quality and reliable PCB. Therefore, it addresses possible issues PCB designers may encounter during PCB design. This helps PCB designers to plan for potential issues during the design phase.
Reduced costs
One of the benefits of IPC 2221A standards is that it helps to reduce costs. Reducing miscommunication and increasing quality minimizes the possibilities of reworks and delays. Also, IPC standards enable companies to reduce resource use and improve efficiency.
Ensures smooth workflow during PCB manufacturing and assembly
The IPC 2221A standard helps to ensure a smooth workflow during PCB assembly and manufacturing. Also, the PCB manufacturing process involves several stages. With the right information and procedure, the PCB manufacturer can work through these stages without difficulty.
Conclusion
IPC 2221A creates standards for PCB design. As the technology world experiences advancements, specific standards require update. Therefore, the IPC 2221A standard has some new focus standards and updates. We have discussed the impact of IPC 2221A standard in PCB design. There is no doubt that this standard has a positive impact not only on PCB design, but also PCB manufacturing and assembly.
