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Sharing design intent and stackup information with your manufacturer at the beginning of the design process avoids manufacturing and assembly issues that may impact the product design, and eventually, delay the product delivery. However, without having a standard mode of communication for exchanging manufacturing data, it is likely that the information will be misinterpreted or completely lost during the review cycle. Data created manually may have multiple variations and may lack essential parameters. All these issues can be addressed if IPC-2581 standards are followed by designers and manufacturing experts. With the support of the IPC-2581 standards enabled within Allegro^® PCB Editor, you can generate a single XML file with stackup information and share it with your PCB manufacturer for analysis and comments. The same file can be imported back into Allegro PCB Editor. The IPC-2581 file generation does not involve any manual intervention and ensures design accuracy.

Why IPC-2581

Before the IPC-2581 standards were defined, the manufacturing information was exchanged between designers and manufacturers through emails and documents. Separate files were generated, compressed, and sent with emails. Since it was done manually, the complete process was way too time-consuming and error-prone. IPC-2581 uses a single file system through which the stackup data can be exported or imported easily using a simple user interface in Allegro PCB Editor. Whenever you make any changes in your design stackup, export the stackup in a file and send it to your manufacturer to make sure it meets the design criteria and passes fabrication checks. You can exchange stackup information with your manufacturer in the beginning as well as while designing. The IPC-2581 file has a fixed template and includes all the important parameters, such as layer structure, layer stack sub-groups, materials definition, dielectric materials, conductive materials, coatings, and material characteristics.

When to Exchange Stackup

The stackup details are often exchanged after component placement as it gives you a sense that the design has sufficient layers. If you are defining a new layer stackup, you might want to discuss it with your manufacturing partner before actually laying out the design. It is good to communicate with your manufacturer from the beginning of the design or at least after placing the main components of the design. If the layer stackup is reused from a reference design, you can import the IPC-2581 file with the stackup information from the reference design into your working design.

Whether you are creating a new one or reusing one from a previous design, it is easy to export and import the stackup information within Allegro PCB Editor using Cross-section Editor. The user interface of Cross-section Editor displays a graphical representation of layer stackup reflecting the changes made to the layers. In this post, I will walk you through the steps of exporting and importing the IPC-2581 file from Cross-section Editor in Allegro PCB Editor.

Exporting IPC-2581-Formatted Stackup Data from Allegro PCB Editor

The Cross-section Editor window provides an option to export the layer stackup details in IPC-2581 file format. To generate this file, do the following:

1. Choose Setup – Cross-section.
2. In the Cross-Section Editor window, choose Export – IPC-2581.
   
   
   
   
3. In the file browser, specify a name and the location for the file and click the Save.
   The IPC-2581 file with stackup data is created in the specified directory.

The following image shows a sample XML-formatted IPC-2581 file where you can see layer information for the TOP and DIELECTRIC layers. You can send this file to the manufacturing partner for analyzing the stackup.

Importing IPC-2581-Formatted Stackup Data into Allegro PCB Editor

Manufacturing experts can edit the layer information in the same IPC-2581 file and send it back. Use the following steps to import the file using the Import menu in Cross-section Editor:

1. Choose Setup – Cross-section.
2. In the Cross-Section Editor window, choose Import – IPC-2581.
3. In the file browser, locate and select the IPC-2581 (*.xml) file, which you received.
4. To import the file in PCB Editor, click the Open button.

After importing the file, you can view the modified layer attributes along with graphical details. A Technology Difference Report is also generated, which shows the difference in stackup before and after import. 

You can also import any third-party generated IPC-2581 file into Allegro PCB Editor. Another way to generate the IPC-2581 file is to use the Export – IPC-2581 option in Allegro PCB Editor. You can refer to my previous blog to read about this option. 

Watch the Stackup Exchange with IPC-2581 - Feature Video for a quick view of the steps explained in this post.

Summary

Exchanging PCB manufacturing data in the IPC-2581 format is error-free and easy. By simply exporting and importing the stackup information through a single file through the Cross-section Editor, you can review and modify the layer information of your design.

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