PCBA Tech - Design skills for different types of PCBA manufacturing

Various factors affect the use of equipment in electronic equipment, such as performance, environment, and functionality. These same parameter types will affect the PCB construction process. Based on a set of clearly defined steps, the factors that need to be considered in the manufacture of boards for critical applications (such as aerospace, automotive, and industrial applications) are beyond what is usually required for commercial electronics.

Let's take a look at these different PCBA manufacturing types based on the application and establish design skills to ensure that your circuit board meets the requirements of its intended use.

IPC Classification System

The world's leading associations help manufacturers to pass reliable certifications, education and training standards, innovative solutions, thought leadership, advocacy and industry wisdom through the following channels to create better electronic products. IPC (Connected Electronics Industry Association).

The IPC standard includes the use category identification of various electronic equipment, such as the IPC-6011 standard. In general, this classification system contains three general categories, which reflect the gradual increase in complexity, functional performance requirements, and frequency of testing and inspection.

These three categories indicate the quality level that each type of circuit board should be built, and the classification that the CM must follow when the developer builds the PCB by himself.

Categories in the IPC Classification System

1. IPC Class 1 includes general electronic products, such as computers (desktops and laptops), computer peripherals and consumer products. In all cases, these devices are suitable for applications with cosmetic defects, and the main requirement is the functionality of the PCBA.

2. IPC Class 2 applies to dedicated service electronic products, such as complex business machines, instruments and communication equipment. These are used equipment that requires extended life and high performance. Although this classification requires uninterrupted service, it is not a critical requirement and some cosmetic defects are also allowed.

3. IPC Class 3 is suitable for electronic products that require high reliability in harsh working environments. In addition, this category also includes equipment and equipment that must provide on-demand or continuous performance. In addition, these devices or equipment have zero tolerance for downtime and must be performed when needed. Examples of such devices, devices or systems include space applications, such as NASA oxygen generation systems, flight control systems, and life support systems. All in all, PCBA in this category is suitable for applications that are critical to service and require a high level of assurance.

It is important to note that the final performance level of PCBA (assembly, soldering, cleaning and testing) cannot be higher than the performance level specified for bare board or prefabricated PCB. Therefore, to obtain a Class 3 PCBA, IPC Class 3 must be specified for manufacturing.

The classification system of various products strictly follows strict design considerations. The following are three industries, which comply with the IPC-6011 standard.

We will start with 3 categories, including mission-critical equipment and systems and the most rigorous guidelines. In addition, there is no industry that relies on its equipment and procedures more than this industry. Aerospace, of course, except for the medical field.

Aerospace applications

1. Reliability is the key: This means zero tolerance for failures and an extended life cycle. Therefore, designers and manufacturers need to avoid using any cutting-edge technology when designing and manufacturing PCBs, and comply with standard, proven technology.

2. Use heavy copper: In space, they control heat by dissipating heat. Therefore, when building for these applications, use a heavier copper design, that is, 4 or 5 ounces of copper with thermal vias, and use the chassis for heat dissipation.

3. Material selection: use polyimide (wooden board), especially in applications that need to extend the service life (that is, more than two or three years). The advantages of using polyimide on your PCB include excellent flexibility, excellent tensile strength, thermal stability, high durability, and chemical resistance.

4. Assembly process and surface finish: Use lead-containing HASL (hot air solder leveling agent) during assembly. For example, ENIG can be used for surface finish.

5. IPC 6012DS: Always refer to this standard because it is technically an enhanced IPC Type 3. For military and space applications, it is also release requirements, quality requirements, minimum plating, etc.

Automotive applications

The automotive industry continues to take its own path towards electric and autonomous vehicles. Only by traveling throughout the PCB industry can growth be achieved. In addition, the need for thermal resistance and longevity makes automotive PCBs different from other industries. Adherence to IPC-6012DAIATF 16949 (ISO 9001 automotive standard) is a key manufacturing requirement. The following are the design and manufacturing skills of the automotive industry:

1. If there are no other specifications, please use Class 3 specifications for all circuit board characteristics.

2. The pitch and pad specifications are within the tolerance standard of IPC-6012DA.

3. The drilling needs to meet the size and quality requirements of IPC-6012DA, and meet the equipment aspect ratio of the contract manufacturer.

4. Solder mask specifications need to meet the tolerance standards of IPC-6012DA.

5. Ensure that your CM applies reasonable quality control, including automatic optical inspection (AOI) for visual inspection throughout the assembly and manufacturing process.

6. CM should comply with strict cleanliness guidelines and clean the circuit board after each operation to avoid excessive debris, including before and after the solder mask.

Industrial application

With industrial PCBA, we embed the board into a wider industrial production system. In addition, these boards are usually customized or have special requirements. The following are some production techniques that need attention:

1. Use conformal coating (IPC-CC-830C standard) to protect the circuit board from moisture and debris.

2. Selection of materials: The mechanical, thermal and electrical properties of the materials should be considered when selecting. In addition, ensure that the PCB type can withstand the challenges of structure, heat, or possible high-speed industrial environments.

3. Use correct wiring to ensure proper copper wire weight, impedance and length. Correct routing can be converted into signal integrity and necessary current-carrying capacity.

4. Tests: These types of tests include solvent extraction test (debris), AOI (solder joint and component placement) and peel test (adhesion) resistivity.

5. Use DFM inspection and simulation to analyze the power transmission network (PDN) and thermal resistance of the circuit board.

The expected environment of PCBA determines the expected level of quality, performance, function and life cycle. For critical applications, designing for harsh environmental conditions is often necessary. Cycle Automation Cooperate with PCBA manufacturing partners who can meet these stringent requirements, and work with assembled boards to meet any classification level standards.