Comment sélectionner la bonne épaisseur de cuivre pour PCB?

Ryan est l'ingénieur électronique senior chez MOKO, avec plus de dix ans d'expérience dans cette industrie. Spécialisé dans la conception d'implantation de circuits imprimés, conception électronique, et conception embarquée, il fournit des services de conception et de développement électroniques pour des clients dans différents domaines, de l'IdO, LED, à l'électronique grand public, médical et ainsi de suite.
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Les traces de cuivre sur une carte de circuit imprimé transportent des signaux électroniques et distribuent l'énergie entre les composants et les appareils. Ce réseau complexe de voies conductrices permet à tous les éléments fonctionnels de la carte de fonctionner en harmonie. One of the most important design decisions when engineering a PCB is determining the appropriate PCB copper thickness for the traces. Dans cet article, we’ll look closely at the common copper thicknesses used in PCBs, discuss why utilizing thicker copper is advantageous in high power applications, and go over the key factors designers must consider when selecting the optimal circuit board copper thickness for their particular circuit requirements and constraints. Plongeons dedans.

Common Copper Thicknesses Used in PCB

Copper thickness refers to the weight of the copper foil laminated onto the Substrat PCB, expressed in ounces per square foot (oz/ft2). Typical weights range from 0.5 oz to 3 oz:

0.5-1 oz copper thickness: An extremely thin copper foil at 0.0007 inches thick. Used for lightweight, low current PCBs where tight trace spacing and thin board profile are needed. The minimum trace size and spacing are very small with one ounce copper thickness.

1-2 onces de cuivre: The standard and most common copper weight for general PCB designs. It provides a balance of electro-thermal performance and manufacturability. Suitable for most medium complexity PCBs.

3 onces de cuivre: Considered a heavy copper PCB. It is robust enough for high current power circuits, which can handle up to around 8-10A per trace before overheating or voltage drop becomes an issue. It provides enhanced stability and reliability.

Why Use Heavy Copper in PCB?

While utilizing heavy copper foils increases PCB cost, there are important advantages that make it the right choice for high power circuit designs:

  • Handles higher current without overheating tracesThe thicker copper has lower resistance, allowing more current to flow without excessive resistive heating. This prevents damage from over-temperature.
  • Lower voltage drop across traces at high currentsThicker copper traces reduce unwanted voltage drop along the trace length, ensuring signals and power are delivered at the correct levels across the PCB.
  • Improved heat spreading and thermal managementCopper is an excellent thermal conductor. Heavycopper acts as a heat spreader, quickly conducting heat away from hot spots and distributing it over a larger area for dissipation. This enables proper circuit operation at higher temperatures.
  • Withstands high temps and repeated thermal cyclingThe high thermal mass and conductivity of thick copper make it far more resistant to damage from high temperatures and repeated heating/cooling cycles compared to thin foils.
  • Reduces EMI compared to thinner tracesThicker traces generate less electromagnetic interference vs thin traces with identical current, due to the reduced AC resistance. This EMI reduction is beneficial for EMC compliance.
  • Increases overall reliability and product lifetimeThe superior current capacity, performance thermique, and durability of PCB en cuivre lourd enhance the reliability and usable product lifetime, especially in demanding high-power environments.
    PCB en cuivre lourd

How to Choose PCB Copper Thickness?

Selecting the optimal PCB copper thickness for a particular design requires considering several interrelated factors:

  • Current levelsThe expected maximum current in each trace determines the minimum thickness needed to avoid overheating. Par exemple, traces carrying over 5A typically need thicker 2oz copper or more. Match the thickness to the current.
  • Nombre de couches – A PCB with more copper layers allows the use of thinner copper overall, since current can be divided over multiple layers. UNE 2-layer board often needs thicker 2oz copper compared to a 4-layer or 6-layer board for the same current.
  • Target trace resistanceLower resistance requires thicker traces all else being equal. Calculate the resistance per unit length for different thicknesses at the desired trace width to meet resistance targets.
  • Coût – Thicker copper material intrinsically costs more than thin material. Weigh the cost increase against the electrical performance benefits to fit the budget.
  • Manufacturing limitsThick copper over 2oz may require special processing equipment. It also impacts the achievable trace resolution, spacing between traces, and registration accuracy. Consult manufacturer capabilities.
  • Thermal loadsCarefully calculate the overall thermal power dissipation in the PCB to ensure the copper can spread and sink the heat without overheating. Consider ambient temperature and air/liquid cooling options.

Dernières pensées

Selecting the optimal copper thickness in PCB design is a complex balancing act that requires thoroughly analyzing the expected current loads, thermal dissipation characteristics, manufacturability limitations, and material cost tradeoffs. Heavier copper weights with excellent current capacity and thermal performance do come at the price of increased board dimensions and expense. PCB designers must judiciously match the trace copper thickness to the electrical needs and constraints of the application, while considering all interdependent design factors. With informed trace thickness decisions, board performance can be maximized within the available budget and fabrication capabilities. Nous contacter if you need assistance determining the ideal copper weight for your next PCB.

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Ryan est l'ingénieur électronique senior chez MOKO, avec plus de dix ans d'expérience dans cette industrie. Spécialisé dans la conception d'implantation de circuits imprimés, conception électronique, et conception embarquée, il fournit des services de conception et de développement électroniques pour des clients dans différents domaines, de l'IdO, LED, à l'électronique grand public, médical et ainsi de suite.
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