The recently released IPC Connected Factory Initiative scope is similar to other Factory 4.0 models with the same glaring omission: They all seem to assume that the incoming design data can’t be used as-is and must be reviewed and potentially manually modified prior to manufacturing release. The existing error-prone manufacturing process capability design rule knowledge transfer is assumed. And thus, all the existing semi-automatic data transfer process steps are maintained and not improved.
A typical PCB NPI process is pictured in Figure 1. The PCB design is completed and DFM reviewed by the OEM, then the layout data—typically in a non-intelligent Gerber format—is combined with electronic paper (ePaper) documents such as PDF or Excel formats. These are bundled and electronically transferred to the fabricator.
The design rules provided by the fabricator to the designer, which are utilized during the design and DFM review, are typically a short Excel- or PowerPoint-formatted capability matrix. These rules are a subset of those used by the manufacturer during their internal data quality analysis step, often called pre-engineering. These are combined with technical queries (TQs) that have been provided by the manufacturer for prior designs to create the detailed fabricator capability knowledge. Unfortunately, these are incomplete and make it difficult to create a design that matches the supplier capability.
After the data package is received, the fabricator first validates that the received data is complete and does not contain conflicting information. About 20-30% of all data packages fail at this step. Product engineers then review the data against the detailed plant capability and material availability. Issues and questions, or TQs, are listed in an Excel file and transmitted back to the designer via an email.
Design rules, both general and part number-specific, can be updated using the Factory 4.0 architectures. Capturing the data and process knowledge using digital twin concepts allow a significant amount of knowledge to be provided to the OEM to automatically or semi-automatically update their internal design rules.
Figure 1: Typical Factory 4.0 data transfer process.
This current process using existing software requires that humans be involved in the data transfer between the OEM and factory. The existing process utilizes many Lean non-value-added processes because they assume that the incoming data package cannot be fabricated as-is.
Let us do a paradigm shift to have the incoming data ready to produce the manufacturing tooling without any analysis by the fabricator. For argument’s sake, call this “Factory 4.1” data. This process eliminates the creation of ePaper documentation, human based data validation, data analysis and TQ feedback processes by using intelligent-complete design rules and replacing unintelligent data with intelligent IPC-2581 data. IPC-2581 data is compatible with the IPC CFX data, making that transfer seamless.
Figure 2: Proposed “Factory 4.1” data transfer process.
This “Factory 4.1” design rule manufacturing-to-designer knowledge transfer process was common many years ago, back when Happy Holden and Clyde Coombs were young engineers, for captive PCB factories. It is easier to create rules for a captive shop because the designs are generally similar using common design rules and the OEM had to pay for all scrap and rework that was produced (financial motivation). The industry did not have the advanced DFM checking and editing software or intelligent data formats we currently have today.
So, how can we collectively remove the human element from the data transfer and what will be the advantages?
- Provide a complete set of design rules to key customers. These rules do not need to include traveler creation rules, cost, or process information.
- Encourage your customers to provide IPC-2581 intelligent data instead of Gerber based data packages. This will enable automated data integrity, DFM checking, traveler creation and potentially lead to automated CAM.
- This will reduce the front-end engineering cycle time and cost by 25-50%.
- Create KPIs which measure jobs received that track TQs/job and Pareto TQs so you can jointly work with your customers to identify the root causes and eliminate them.
- Encourage your manufacturers to use intelligent IPC-2581 data instead of existing Gerber based packages to reduce your cycle time and data quality issues.
- Require your suppliers to provide detailed design guidelines to enable your teams to create perfect data packages as a standard practice.
- OEM DFM teams spend most of their time chasing answers for TQ questions from fabricators. Refocus them from being reactive to proactive. Focus on obtaining complete design rules from your suppliers to eliminate the TQs items. Change their KPIs.
ECAD & CAM/Engineering software suppliers:
- Update the layout and DFM software to incorporate all the design rules versus just the most common rules.
- Create a KPI which measures how many designs are created and built without any TQs being created.
There is activity in each of these areas in the industry. But there does not seem to be the focus utilizing the powerful information that the Factory 4.0 initiatives will generate that will enable an automated design transfer process to be established.
As Peter Drucker said, “There is nothing so useless as doing efficiently that which should not be done at all.”
Dana Korf is the principal consultant at Korf Consultancy LLC.