Archive for category: Tips & Tricks
“What do PCB fabricators do with my data before they make my PCB?”
“Why can’t they use my data just as I sent it in?” “Why do I need to know? I’m an electronics engineer and they are the board fabricators?”. Our new white paper, “Front-end data preparation”, answers these questions.
An understanding of the front-end data preparation process is important for two reasons, speed and cost. PCBs for time-critical applications need to be delivered fast and on time. If information is missing from the data set supplied or if it is ambiguous or unclear we lose time while the issues are sorted out. The new white paper explains how we verify that the data is complete and clear, to make sure that we deliver the board that you want. Above all, it contains tips on how to present clear and unambiguous data and avoid some of the common traps which can delay deliveries.
Our pooling services have been developed to deliver prototype and small batch PCBs cost-effectively as well as fast and on time. The specifications of each service are based on a choice of base material and on a robust level of manufacturability to ensure the quality of the finished product. The white paper outlines how we check that each design fits the specification of the chosen service. If it doesn’t, we report back the data issues (raise an exception). Are there simple steps which you as a designer or we as fabricators can take to avoid having to use a more expensive option? If so we will propose them. Are there repairs we can make to bring the board back within specification and improve its manufacturability? In many cases we can make these repairs as part of the data preparation process and the white paper has links to more detailed information. Design for manufacturability tips highlight some critical areas. The white paper also links to the free design rule sets which can be uploaded form our website into EAGLE and Altium CAD systems to help ensure that your design meets the specifications of the most cost-effective pooling service.
Although the white paper follows our internal procedures and includes the names of our front-end data preparation stages, our data preparation process follows industry best-practice. So throughout we relate what we do and our design tips to the wider PCB fabrication world. Our goal is to provide a broad set of technical information which will benefit not just our users but also the wider electronics engineering community across Europe.
Download the Eurocircuits-frontend data preparation white paper in PDF format.
To preserve the environment and to make use of the many embedded links to articles on our web site, we recommended that you read this white paper in its digital form.
To produce your board we use your design data in Gerber or EAGLE format and first perform the necessary front end actions as described in our white paper: “What do PCB fabricators do with your data before they make your PCBs?“.
When this is done and your board is ready for production, we save your board’s production data in your account. This data we call the job’s “single image” data. “Single image” means the data we load onto our order-pooling production multi-panels, so it may refer to a single circuit image or to a delivery panel if this is what you have ordered. This is the data that is visualized in the PCB image. You can download the full set from within your customer account.
The download of the single image production data from the Eurocircuits site has been possible since we launched our e-business platform more than 10 years ago. This open business policy has convinced customers over the years to come to us for their prototypes and small series even if they planned to have their large series produced in the Far East. We offer a fast and convenient way to calculate prices and place orders, a thorough data verification and manufacturability analysis and highly professional production processes. Combine this with the possibility to download the verified data and use it for production wherever else you want, and you have the best possible start for the life cycle of your products.
The single image files are name coded by Eurocircuits. But this is no secret either. Let us explain what the files are and what their names stand for.
The format of the files is mainly DPF. This is the internal format for UCAM, the front-end data preparation or CAM (Computer Aided Manufacturing) system we use designed and developed by Ucamco. The paste files can also be downloaded as Gerber data. To read DPF files as well as Gerber data and Excellon drill files we recommend GC-Prevue, available as a free download from www.graphicode.com.
We are sometimes asked if it possible to reload the single image data back into a CAD system. This is totally dependent on the CAD system. We have only input and processed manufacturing data. Other PCB manufacturers can use it for production through their own CAM systems. However the manufacturing data doesn’t contain any component information like foot-print coordinates or a functional net-list where nets are linked to component pin numbers and are described as power, ground, data line, etc… A successful reload of DPF or Gerber production data into a CAD system depends entirely on the functionality available in the CAD-system and should be investigated there.
Our team will gladly answer any queries you may have. Contact us on firstname.lastname@example.org.
Stage 3 – Make production panels and production tools
We now have a stack of orders that are ready to go into production.
Our business model is based on “order pooling”. We make our production more efficient by processing several different orders on the same production panel. More efficient production means lower prices for our customers, especially for prototype and small batch orders. Which orders can be pooled together? This depends on a lot of factors, and finding the right balance is our daily challenge.
We need to consider:
- Delivery term : we separate rush orders from standard delivery orders. If we put both on the same production panel we could find that all panels have rush orders on them. If every job becomes urgent, production efficiency goes down and our delivery performance is affected.
- Order size : we keep large and small orders apart. The higher the number of panels in a job, the longer it takes to process. Production planning becomes less flexible and again we risk deliveries.
- Copper distribution : we discussed this already in our earlier blogs about our new plating simulation tool and the Elsyca Intellitool Matrix plating project. We need to be sure that the designs we pool together don’t reduce each other’s plating quality.
- Classification/complexity of the boards : combining complex jobs with simpler jobs means that the final panel is more complex than it need be and so more expensive to produce. That’s why we have two different pooling services ‘STANDARD pool” for standard boards and “TECH pool” for more complex boards.
- Technology: some technology options clearly can’t be combined with each other, for example different materials, copper weights and build-ups. In other cases combinations might reduce production efficiency or quality. For example we could in theory combine boards with different legend colors on a single production panel. In practice this would need two printing processes and two curing stages. We would lose time at the print stage and risk the quality if the panel went through too many heating/cooling cycles.
The final decision day by day on which orders are combined on which panel is made by highly skilled and experienced engineers. They have a growing number of software tools to help them to make the best decisions, and we are investing a lot of manpower and resources to develop even more powerful tools for the future.
Once the engineer has chosen the orders for the panel, how do we make it ready for production?
Panel preparation for production
Most of the steps below are fully automated processes
- Run a Drill Tool Reduction: on pooling panels we remap all drill sizes larger than 1.00 mm to new tool sizes with a step of 0.10 mm rather than 0.05 mm – provided, of course, that we can still maintain the tolerance specifications of the finished hole size. This can reduce the number of different drill sizes needed by up to 60%, which in turn reduces total drilling times and so cuts cost of your PCB.
- Add any customer-specified markings to the boards on the panel, for example UL markings or customer-specific date-codes.
- Add different test coupons to the panel for inline quality checking. Together these coupons contain specific features which allow us to check all process steps and make sure that the panel meets all production specifications during and after the production.
- Add specific galvanic compensation patterns (“robber/thieving bars”) to the open panel areas. This optimizes the final plating results and ensures that after plating the copper thickness in the holes and on the tracks is within the production specifications.
- Add etch-compensation to meet the panel and production specifications. When we etch down into the copper the nature of the process means that we also etch away a small amount of copper to each side (“under-cut”). Etch compensation makes a small increase in all copper features so that after any under-cutting the feature size is as designed. This is especially important to maintain correct track widths.
- Calculate the other data we are going to need for panel checking and manufacture, like the total copper surface area or the copper distribution, information which we will need for calculating plating currents.
Panel checking and optimization
- Perform a galvanic plating simulation to ensure a uniform layer of plated copper over the entire panel within the production specifications. At this stage our engineers may move the circuits around on the panel or change the galvanic compensation patterns to get the best possible plating result.
- Drill optimization. For each separate drill run on the panel, the complete drill path – the order in which all the holes are drilled – is automatically optimized to get the lowest possible drill time.
- Routing optimization. For each routing operation on the panel, the complete rout path is optimized. Here we rely on experienced production engineers to get the best possible combination of edge finish, mechanical stability of the panel during routing, and shortest routing time.
Panel plating image samples:
Panel output generation
- Drill output: we generate drill output files for each drill operation required on the panel (plated, non-plated, blind, buried). These output files will drive our various drilling machines.
- Rout output: rout output files for all the routing and milling operations needed (board profiling, slots, internal cut-outs). The output files drive the routing machines.
- Plotter output: plot-files for our laser film plotters for all layers produced by photo-imaging (copper layers and soldermasks).
- Legend output: for legend (“component ident” or “silk-screen”) printing we use digital ink-jet printers. As well as the legend pattern the output files can contain an instruction that prints a unique barcode on each individual PCB. When tests are completed this will give our customers who want it the ultimate in traceability.
- Electrical test files for our different electrical test machines. Production panels are electrically tested before the single images are routed out. If needed a single board can also be electrically tested after final board profile routing.
- AOI (Automated Optical Inspection) output generation. AOI testing is an automated optical comparison between the digital data supplied for the PCB and the actual copper layer we have produced. We AOI test all inner layers to detect shorts, opens and other faults which cannot be rectified once the board is bonded. We also AOI test some outer layers depending on the technology level of the panel.
- Other information needed for manufacture such as:
- the surface area and density calculations for copper layers, soldermask layers, plating layers, etc
- panel images
- drilling, routing and scoring drawings etc…
The complete production panel job and all generated output data are packed together in a structured zip container and uploaded to the system.
The production panel is now ready for manufacture. Our production planners decide which production unit is going to actually make the panel (Eurocircuits Kft in Hungary or Eurocircuits Aachen in Germany). The decision is based on the technology required, the size of the job, the delivery term and available capacity.