Common Pick and Place File Formats

There are several commonly used file formats for providing pick and place data to machines. Each format has its own structure and conventions for representing component placement information. Some of the most widely used formats include:

Centroid File Format

The Centroid file format (.txt) is a simple, text-based format that specifies the X and Y coordinates and rotation for each component on the PCB. It is a widely supported format used by various pick and place machine vendors. The file consists of tab-separated fields, with each line representing a single component.

Example of a Centroid file:

Designator    Footprint    Mid X         Mid Y        Ref X         Ref Y         Pad X         Pad Y         TB      Rotation
C1            0805         29.7104mm     27.8003mm    29.7104mm     27.8003mm     29.7104mm     27.8003mm     T       270
R1            0603         57.9120mm     16.5100mm    57.9120mm     16.5100mm     57.9120mm     16.5100mm     T       90
U1            QFP-100      38.1000mm     63.5000mm    38.1000mm     63.5000mm     38.1000mm     63.5000mm     T       0

ODB++ Format

ODB++ (Open Database++) is a comprehensive and standardized format for PCB design data exchange. It includes not only pick and place information but also other manufacturing data such as Gerber files, drill files, and BOM. ODB++ uses a directory structure with multiple files to represent different aspects of the PCB design.

The pick and place data in ODB++ is typically stored in the “pickplace.txt” file within the “steps” directory. This file follows a similar structure to the Centroid format, with tab-separated fields specifying the component designator, package, coordinates, and rotation.

IPC-D-356A Format

IPC-D-356A is a standard format developed by the IPC (Association Connecting Electronics Industries) for representing netlist and component placement information. It is a text-based format that uses specific record types to define the PCB data.

In the context of pick and place, the IPC-D-356A format uses the “P” record type to specify component placement. Each “P” record includes fields such as the component designator, reference designator, X and Y coordinates, rotation, and side of the board.

Example of IPC-D-356A pick and place records:

P  C1        C1        29.7104  27.8003  270  T
P  R1        R1        57.9120  16.5100  90   T
P  U1        U1        38.1000  63.5000  0    T

Creating Pick and Place Files

To generate pick and place files for a PCB design, designers typically use PCB design software or specialized tools. Most PCB design tools offer built-in functionality or plugins to export pick and place data in various formats.

When creating pick and place files, it’s important to consider the following aspects:

1. Coordinate System: Ensure that the coordinate system used in the pick and place file matches the requirements of the manufacturing process. Common coordinate systems include absolute coordinates (relative to the PCB origin) and relative coordinates (relative to a reference point).

2. Units: Specify the units used for coordinates and dimensions in the pick and place file. Common units include millimeters (mm) and mils (thousandths of an inch).

3. Rotation: Define the rotation of each component in the appropriate format. Rotation values are typically specified in degrees, with 0 degrees representing the default orientation.

4. Side of the Board: Indicate whether the component is placed on the top (T) or bottom (B) side of the PCB.

5. Reference Designators: Ensure that the reference designators in the pick and place file match those in the schematic and PCB Layout.

Here’s an example of exporting a pick and place file from Altium Designer:

1. In Altium Designer, go to File > Assembly Outputs > Pick and Place Files.
2. Select the desired output format (e.g., Centroid, ODB++, IPC-D-356A) and configure the export settings.
3. Click “OK” to generate the pick and place file.

Other PCB design tools, such as KiCad, Eagle, and Mentor Graphics PADS, have similar procedures for exporting pick and place data.

Utilizing Pick and Place Files in Manufacturing

Once the pick and place file is generated, it is used in the PCB assembly process to program the pick and place machine. The machine reads the file and uses the provided coordinates and component information to accurately place components onto the PCB.

To ensure smooth integration with the manufacturing process, consider the following tips:

1. Communicate with the Manufacturer: Discuss with the PCB assembler to determine their preferred pick and place file format and any specific requirements they may have.

2. Verify File Accuracy: Double-check the generated pick and place file to ensure that all components are correctly represented and the coordinates match the PCB layout.

3. Include Necessary Files: Provide the manufacturer with all the necessary files for PCB-Assembly/”>PCB assembly, including the pick and place file, Gerber files, drill files, and BOM.

4. Review Manufacturing Feedback: Collaborate with the manufacturer and review any feedback they provide regarding the pick and place file or the overall manufacturing process.

By understanding pick and place file formats and effectively utilizing them in the manufacturing process, designers can ensure accurate and efficient PCB assembly.

Pick and Place File Format Comparison

To help understand the differences between the common pick and place file formats, let’s compare them side by side:

Feature	Centroid	ODB++	IPC-D-356A
File Extension	.txt	.tar.gz (multiple files)	.ipc or .txt
Coordinate System	Absolute	Absolute	Absolute
Units	mm or mils	mm or mils	mm or mils
Rotation Format	Degrees	Degrees	Degrees
Side of Board Indicator	T/B	T/B	T/B
Component Attributes	Designator, Footprint, Coordinates, Rotation	Designator, Package, Coordinates, Rotation	Designator, Reference Designator, Coordinates, Rotation, Side
Other Manufacturing Data	No	Yes (Gerber, drill, BOM)	No
Widely Supported	Yes	Yes	Yes

As you can see, all three formats share similarities in representing component placement data, but they differ in file structure, additional manufacturing data inclusion, and specific field naming conventions.

Frequently Asked Questions (FAQ)

1. Q: What is a pick and place file?
   A: A pick and place file is a digital file that contains information about the placement of components on a printed circuit board (PCB). It specifies the coordinates, orientation, and reference designators of each component to guide the pick and place machine during PCB assembly.

2. Q: Why are pick and place files important?
   A: Pick and place files are crucial for accurate and automated PCB assembly. They provide the necessary data for the pick and place machine to precisely place components onto the PCB, ensuring proper alignment and orientation. Accurate pick and place files help minimize assembly errors and improve manufacturing efficiency.

3. Q: What are the most common pick and place file formats?
   A: The most common pick and place file formats include:

4. Centroid (.txt): A simple, text-based format that specifies component coordinates and rotation.
5. ODB++ (Open Database++): A comprehensive format that includes pick and place data along with other manufacturing files.

6. IPC-D-356A: A standardized format developed by the IPC for representing component placement information.

7. Q: How do I create a pick and place file?
   A: Pick and place files are typically generated using PCB design software or specialized tools. Most PCB design tools have built-in functionality or plugins to export pick and place data in various formats. The process usually involves selecting the desired output format, configuring export settings, and generating the file.

8. Q: What information is included in a pick and place file?
   A: A pick and place file typically includes the following information for each component:

9. Reference designator
10. Footprint or package type
11. X and Y coordinates
12. Rotation angle
13. Side of the board (top or bottom)
14. Additional attributes depending on the specific format

By understanding pick and place file formats and their role in PCB assembly, engineers and technicians can ensure accurate and efficient manufacturing processes.