作为电子产品的重要组成部分， 印刷电路板 (PCB)在实现电子产品的功能中起着关键作用，这导致PCB设计的重要性日益凸显，因为PCB设计的性能直接决定了电子产品的功能和成本。 良好的PCB设计可以让电子产品远离许多问题，从而保证产品能够顺利制造并满足实际应用的所有需求。

在所有有助于 PCB 设计的元素中，制造设计 (DFM) 绝对是必不可少的，因为它将 PCB 设计与 PCB 制造联系起来，以便在电子产品的整个生命周期中及早发现问题并及时解决问题。 One myth is that the complexity of PCB design will increase as manufacturability of electronics is considered at the PCB design stage. In the design life cycle of electronic products, DFM can not only make electronic products participate in automatic production smoothly, and save labor costs in the manufacturing process, but also effectively shorten the manufacturing time to ensure the timely completion of the final electronic products.

PCB可制造性

通过将可制造性与 PCB 设计相结合，制造设计是实现高效制造、高质量和低成本的关键因素。 The research of PCB manufacturability covers a wide range, usually divided into PCB manufacturing and PCB assembly.

LPCB production

For PCB manufacturing, the following aspects should be considered: PCB size, PCB shape, process edge and Mark point. 如果在PCB设计阶段没有充分考虑这些方面，除非采取额外的处理措施，否则自动贴片机可能无法接受预制PCB板。 更糟糕的是，有些板材无法使用手工焊接自动制造。 As a result, the manufacturing cycle will be longer and labor costs will increase.

1. PCB size

每个芯片安装商都有自己想要的PCB尺寸，根据每个安装商的参数而有所不同。 例如，芯片安装商接受的最大 PCB 尺寸为 500mm * 450mm，最小 PCB 尺寸为 30mm * 30mm。 这并不意味着我们不能处理小于 30mm x 30mm 的 PCB 板组件，当需要更小的尺寸时可以依靠拼图板。 当只能依靠人工安装，人工成本上升，生产周期失控时，贴片机永远不会接受过大或过小的PCB板。 Therefore, in the PCB design stage, the PCB size requirements set by automatic installation and manufacturing must be fully considered, and it must be controlled within the effective range.

下图说明了华秋DFM软件完成的PCB板设计文档。 作为 5×2 板，每个方形单元都是一个单件，尺寸为 50mm x 20mm。 The connection between each unit is achieved by V-cut/V-scoring technology. In this image, the entire square is shown with a final size of 100mm by 100mm. 根据以上要求，可以得出板子尺寸在可接受范围内的结论。

2. PCB shape

In addition to PCB size, all chip SMT machines have requirements for PCB shape. 一个普通的 PCB 应该是长宽比为 4:3 或 5:4（最好）的矩形。 If the PCB is irregularly shaped, additional measures must be taken prior to SMT assembly, resulting in increased costs. 为防止这种情况发生，PCB 设计阶段必须将 PCB 设计成通用形状以满足 SMT 要求。 然而，这在实践中很难做到。 当某些电子产品的形状必须是不规则的时，必须使用印章孔使最终的PCB具有正常的形状。 组装时，可从PCB上去除多余的辅助挡板，以满足自动安装和空间要求。

下图为不规则形状的PCB，加工边由华秋DFM软件添加。 The whole circuit board size is 80mm * 52mm, and the square area is the size of the actual PCB. The size of the upper right corner area is 40mm by 20mm, which is the auxiliary craft edge produced by the bridge of the stamp hole.

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3.工艺端

To meet the requirements of automatic manufacturing, process edges must be placed on the PCB to secure the PCB.

在PCB设计阶段，要提前预留5mm宽的工艺边缘，不留任何元器件和走线。 技术指南通常放在PCB的短边上，但当纵横比超过80%时可以选择短边。 组装完成后，可以去除工艺边缘作为辅助生产角色。

4. Mark point

For PCBS with components installed, Mark points should be added as a common reference point to ensure that component locations are accurately determined for each assembly device. 因此，Mark 点是自动化制造所需的 SMT 制造基准。

Components require 2 Mark points and PCBS require 3 Mark points. These marks should be placed on the edges of the PCB board and cover all SMT components. 标记点与板边的中心距至少应为 5mm。 对于双面SMT元件的PCBS，Mark点应放在两侧。 If the components are too close together to place Mark points on the board, they can be placed on the edge of the process.

LPCB assembly

PCB组装，简称PCBA，其实就是将元器件焊接到裸板上的过程。 为了满足自动化制造的要求，PCB组装对组装封装和组装布局有一定的要求。

1. 组件的包装

PCBA设计过程中，如果元器件封装不符合标准，元器件靠得太近，则不会发生自动安装。

为了获得最佳的元件封装，应使用专业的EDA设计软件，以符合国际元件封装标准。 During PCB design, the aerial view area must not overlap with other areas, and the automatic IC SMT machine will be able to accurately identify and mount the surface.

2. Component layout

元件布局是PCB设计中的一项重要任务，因为其性能直接关系到PCB外观和制造工艺的复杂程度。

在元件布局时，应确定 SMD 和 THD 元件的装配面。 在这里，我们将 PCB 的正面设置为组件 A 侧，将背面设置为组件 B 侧。 The assembly layout should consider the assembly form, including single layer single package assembly, double layer single package assembly, single layer mixed package assembly, Side A mixed package and side B single package assembly and side A THD and side B SMD assembly. 不同的组装需要不同的制造工艺和技术。 Therefore, in terms of component layout, the best component layout should be selected to make manufacturing simple and easy, so as to improve the manufacturing efficiency of the whole process.

In addition, consideration must be given to the orientation of component layout, spacing between components, heat dissipation, and component height.

一般来说，组件方向应该是一致的。 Components are laid out in accordance with the principle of minimum tracking distance, based on which components with polarity markers should have uniform polarity directions, and components without polarity markers should be neatly aligned along the X or Y axis. 元件高度应达到4mm，元件与PCB之间的传输方向应为90°。

为了提高元件的焊接速度，方便后续检查，元件之间的间距要一致。 Components in the same network should be close to each other and a safe distance should be left between different networks according to the voltage drop. 丝印和焊盘不能重叠，否则元件将无法安装。

Due to the actual operating temperature of the PCB and the thermal characteristics of the electrical components, heat dissipation should be considered. 元器件的布局应注重散热。 如有必要，请使用风扇或散热器。 功率元件应选用合适的散热器，热敏元件应远离热源。 高组件应放在低组件之后。

更多的细节应该放在PCB DFM上，在实践中积累经验。 例如，高速信号 PCB 设计要求有特殊的阻抗要求，应在实际制造前与电路板制造商讨论以确定阻抗和分层信息。 为了准备在布线密集的小尺寸PCB板上生产，应与PCB制造商讨论最小布线宽度和通孔直径制造能力，以确保这些PCBS的顺利生产。