PCB公差と電子デバイスへの影響

目次

What are PCB Tolerances?

Generally, tolerance is the property of any product or component that defines the range of values or its physical qualities that support the product’s ability to function well, be appropriately designed, and be displayed well. 

As we all know, tolerances have an impact on the manufacturing and design of electronic devices. Whether it is a simple screw, a simple passive 電子部品, a huge industrial system, or even a printed circuit board, all depend on tolerance. Even our domestic electrical equipment and devices are manufactured with a specific tolerance. For example, in European countries, the tolerance for electrical devices is 6% of 230V.  It means that the fluctuations that are in the range of 6% can be supported by electrical and electronic devices. Printed circuit board tolerance refers to acceptable fluctuations or variations in the properties and dimensions of the printed circuit board during its manufacturing process.

PCB tolerance is the allowable limit of variations in thickness, hole, dimensions, characteristics, nominal values, and other parameters of the PCB. These tolerances are very essential to consider for the effectiveness, reliability, and functionality of electronic devices. When you go for a new design of your product or electronics device, you consider some basic set of dimensions that are named as nominal values or nominal dimensions. The printed circuit boards that we manufacture and assemble are designed according to IPC-A-600 standards. In this article, we will study the significance, essential factors, specific dimensions, and other requirements for PCB tolerance, how they are set and determined, and their impact on the overall functionality of printed circuit boards.

PCB Tolerance 

Figure 1: A typical PCB for Tolerance Configuration

PCB Tolerance Specification Table and Manufacturing
Capabilities.

Via Hole Finish

STANDARD

ADVANCED

Laser Micro バイアス

.004″

.002″

Blind/buried バイアス

.004″

.002″

Laser パッド

.004″

.002″

Minimum Drilled Hole サイズ

.012″

.0079″

Drilled Hole to

.008″

.007″

Castellation

はい

はい

Finish 表面

 

 

Tin Lead Plating 厚み

.0003″ to .0005″

Less .0005″

Tin Nickel Plating 厚み

150 Micro インチ

250 Micro インチ

Low Stress Nickel

100 Micro インチ

250 Micro インチ

金メッキ 厚み

30 Micro インチ

As Specified

Electroless Nickel/イマージョンゴールド

はい

はい

Immersion Gold

はい

はい

イマージョンシルバー

はい

はい

Entek 106A HT

はい

はい

ハスル

はい

はい

TOLERANCES

 

 

Plated Hole Tolerances (+/-)

.002″

.001″

Non-Plated Hole Tolerances (+/-)

.001″

.001″

ファブリケーション 公差 (+/-)

.005″

.003″

Vision Rout (+/-)

.003″

.002″

Laser Rout (+/-)

.002″

.001″

PCB Tolerances Table

 

標準

アドバンスト

Maximum Layer Count

20L

28L

最大パネルサイズ

21”x24” (533x610mm)

24”x42” (610x1067mm)

Maximum Finished Thickness

0.126″ (3.2mm)

0.256″ (6.5mm)

Minimum Finished Thickness

0.006″ (0.15mm)

0.004″ (0.10mm)

Minimum Core Thickness

0.002” (50um)

.0015” (38um)

Trace/Space (H oz)

0.003”

.0025”

Maximum Aspect Ratio

14:1

25:1

Minimum Mechanical Drill

0.008″ (0.20mm)

0.006″ (0.15mm)

Minimum Laser Drill

0.004″ (0.10mm)

0.003″ (0.076mm)

Min. ソルダーレジスト ダム

0.003″ (76um)

0.0025″ (64um)

Max. Base 銅の厚み

5 oz (75um)

6 oz (210um)

インピーダンスコントロール

+/- 8%

+/- 5%

Why PCB Tolerances are important.

As technology advances very rapidly, プリント基板製造 standards are also becoming increasingly in demand. To meet these standards for customer needs, manufacturers must have good knowledge regarding printed circuit boards, their different manufacturing components, their design specifications, and the required PCB tolerances. The configuration of PCB tolerance is an important issue to ensure the functionality and effectiveness of electronic components and PCB design. Deviations from the given tolerance by the manufacturer can cause several issues, like electrical connection issues on PCB pads, signal interference, and degraded component efficiency. The success of PCB manufacturing depends on reliability and process consistency. To achieve this, a well-planned specification with strict tolerances must be maintained during the PCB manufacturing process. In the field of PCB fabrication and manufacturing, the word tolerance refers to a permittable deviation from the specified value.

For example, the PCB trace width tolerance is ± 0.005 inches. It means that the width of the PCBトレース can be a maximum of 0.005 inches. Tolerance is important in PCB fabrication because it ensures that the PCB components will fit as required in the design and that the final product will function smoothly and properly. The following are the main reasons why PCB tolerances are essential to consider in the printed circuit board manufacturing process:.

Improved PCB functionality:

If you are manufacturing components of a printed circuit board that are compatible with other components, then it is necessary to define your PCB tolerances. If a product having even a minor mistake or variation in PCB size can result in your product’s weak functionality or useless performance.

Tolerance Makes the Market Enhanced:

Although it takes a longer time and more understanding to configure and set up the tolerances at the beginning of PCB manufacturing, this extra step will save your time in the long-life cycle of your final product.  Any mismeasurements, errors, and inadequate product design can slow your market growth by weeks or even several months while you will wait for new components to be manufactured on the PCB for your pcb manufacturing process. Tight specifications of PCB tolerances can benefit your electronic device’s precision in a competitive market.

Tolerance Minimize PCB complexity and ambiguity.

The most effective factor that degrades the manufacturing process is ambiguity. It is like an enemy to the PCB manufacturing process. If you don’t decide in the beginning what you want to design and for which electronics product you want PCB manufacturing, you may end up with an incorrect design and layout. Tolerances remove all the ambiguity in the PCB manufacturing and design. It  makes the PCB Manufacturers  life easier. Consider that, if your PCB design does not meet the product specifications within ± 0.002 mm, then there is no need for such PCB fabrication and product manufacturing to put all the struggle into achieving a high level of accuracy and precision.

Makes the PCB cost-effective:

Tolerance is beneficial for making PCB manufacturing cost-effective. It means that when you define your PCB tolerances, you will only pay for the manufacturing components to be used, materials, and employees if you need to achieve the desired results from the product.

Tolerance makes the Look Pleasant:

Tolerance controls both parts of the PCB design’s dimensions and positions, which contribute to improving the final look of your printed circuit board or final electronic device. It makes the look of the electronic product more pleasant.

PCB work for reasonable errors:

Tolerance assumes a small amount of error. But only up to the range that the part of the electronic device remains operational. If you set  up all PCB component tolerances in the beginning, then there are fewer chances that you will replace or redesign the circuit board, Tolerances are determined on the basis of specific design requirements, manufacturing qualities, and industry demand. Factors such as PCB circuit complexity, component type, and desired application influence the tolerance ranges for PCB fabrication. The following are some major PCB tolerances offered by.

Determining PCB Tolerances and Design Specifications

PCB Board Thickness:

PCB fabrication with an accurate thickness is essential for its better performance. Therefore, the tolerance for permissible variation in thickness is a crucial consideration. The standard tolerance for printed circuit board thickness is ± 10%. This means that the PCB can be manufactured 10% thicker or 10% thinner than the standard specified thickness, and still it will work in electronic devices.

PCB Drilling Tolerance:

Drilling a printed circuit board is an essential part of the PCB manufacturing process, but it is also a challenging and complex task during the PCB fabrication and manufacturing process. This is because printed circuit boards are extremely thin in size and fragile, and sometimes a minor mistake or error can damage the entire circuit board. The drilling tolerance is usually specified in terms of the width of the hole that is to be drilled on the circuit board. For instance, a tolerance of plus ± 0.005 inches means that the hole must be drilled within the range of ±0.005 inches to get the desired results.

銅の厚さ:

The copper thickness on the printed circuit board must be within a certain tolerance range for the proper function of the PCB. The copper thickness for PCB manufacturing is typically ±10% of the standard thickness. It is very important in the プリント基板製造工程 because copper thickness determines the amount of current flow through the printed circuit board. Too thin copper will resist the current flow, and too thick copper will allow more current through the PCB, which will affect the overall performance of the PCB. Due to the high current flow, the circuit board can be damaged.

Impact on PCB Quality

Strict obedience to printed circuit board tolerances is essential for maintaining high quality standards in electronics manufacturing. If the PCB design meets the specified tolerances for electronic devices, then manufacturers can reduce the risk of errors, inconsistencies, and defects in the final product manufacturing.

PCB Tolerance Management:

Effective PCB tolerances Management requires close collaboration between design engineers and PCB manufacturers. Clear communication of tolerances, use of advanced manufacturing techniques, and thorough design evaluation and reviews contribute to effectively controlling and optimizing PCB tolerances. sign the parts later.

Common Mistakes and Challenges in PCB Tolerances

We see that PCB tolerances are very important in the manufacturing process, but it is not as easy as we read and consider. If you ignore the tolerance property in PCB manufacturing. You can face some challenges and miscalculations that arise from:

No experience with materials and manufacturing tools:

If your PCB designer is inexperienced with designing and manufacturing tools, your tolerances may go wrong, which will affect the final electronic product.

Ignoring steps in PCB manufacturing:

One of the common mistake is ignoring to define tolerances at each and every step of pcb manufacturing process.

Missing Tolerance:

To integrate or  adjust one a component inside another part you need to configure tolerances for every part. Missing any one components tolerance in manufacturing process can cause product failure.

Lacking Clear Direction:

Clear direction of knowing product design is necessary. If you don’t explain your pcb manufacturer that which product you require to design, for what purpose you need this product or how you desire its look then they can’t figure out all the tolerances during its manufacturing process.

Hence, it’s very crucial to work with experienced designers, manufacturers which can estimate the exact pcb tolerance so it will benefit you in the product. Skilled and authentic PCB Manufactures have a vast understanding of components selection, advanced manufacturing  methodologies.

結論

In short words understanding and maintaining the right pcb tolerances are crucial aspects of the printed circuit board manufacturing process. By ensuring precise pcb tolerances, electronics devices manufacturers can enhance the performance, functionality and reliability of their products. Following major pcb tolerances in manufacturing process ultimately contributes to the overall efficiency, quality and functionality of electronic devices.

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