Your PCB Visualizer questions answered

Since it was launched in 2012, PCB Visualizer has processed around 100,000 PCB designs. Most of these have either validated the customer’s data-set or raised clear issues (missing files, track widths or isolations out of specification, etc.). But every day PCB Visualizer presents results on a few jobs (perhaps 1 – 2% of the total) which are not clear to our customers, so they contact us by chat, phone or email for clarification. Many of these questions are the same, so it is worthwhile now to explain how PCB Visualizer works and what it is designed to do.

PCB Visualizer is an automatic Gerber checker, running a preliminary analysis on customers’ data either prior to quotation or prior to order. The purpose of the check is to ensure that all the data files are present and there are no major data issues which will cause an exception and hence delay production once an order is placed.

This is not the only check that we will carry out on your order. Our engineers will re-check your data 100% while preparing the production data used to manufacture your PCB (more on this process). This means that in many cases where PCB Visualizer raises an issue, you can place your order confident that our engineers will resolve the issue without any problem.

ACTION tips.

  • If you need to change your order details or upload a new data-set to sort a PCB Visualizer issue, click the Modify button in the Basket menu. If you want to change the order details without uploading new data, just click Continue in the “Complete action” menu: there is no need to reload an unchanged data-set.
  • If you want to check the actual production data, use the “Pre-production check” function under the “Calculate and order” tab

PCB Visualizer is a Gerber analysis tool. That means it works on lists of shape definitions and X,Y co-ordinates for layer and drill information. PCB Visualizer:

  1. Builds a map of each layer from the files. Note that the co-ordinates are not necessarily presented in any logical order.
  2. Aligns the layers with each other. If the layers are not aligned in the CAD data, this is a statistical process.
  3. Determines the board outline. If/when Gerber attributes (see blog) become widely used, the designer will be able to assign a “profile” attribute. Until then, looking for an outline can cause issues.
  4. Determines the stack up. This is based partly on file names and partly on an analysis of the contents of each layer. In the absence of fixed layer naming conventions this can also cause issues.
  5. Analyses the build found against the order: are all files required by the order present in the data set? Are all layer files in the data set included in the order?
  6. Analyses each layer for minimum track, minimum isolation, etc., assign a pattern class and drill class and compare with the order.
  7. Analyses drill and copper layers for annular ring values and compares them with the order.
  8. Completes the report by reading in other information from the order.

What are the most common questions our customers ask us?

1. Why is my job taking so long to process?

There are several possible reasons:

  • An average job takes 2 – 3 minutes to process and we process 6 jobs simultaneously. We receive around 300 orders a day, but they don’t come in evenly throughout the day. So at busy times there is quite a queue of jobs being processed. Our development engineers are always looking at ways to speed up processing.
  • Some jobs have very large data files. This applies especially to boards with plane areas or layers built up from fine-line draws. In these cases PCB Visualizer may need to process tens of thousands of vectors.
  • Sometimes there are software issues or a server is down. We always try to fix these as quickly as possible.

If it’s not a busy time of day (late afternoon usually) and your job has normal size files but is still taking more than an hour to process, contact us by chat.

2. What do the flags mean?

There are no issues with your job. You can proceed to order.

PCB Visualizer could not import all the data or could not work out the correct build. Check the associated message to get more information on the issue.

PCB Visualizer has found a non-critical issue. You can place your order as our engineers will probably be able to resolve the issue at the tool-preparation stage. But you might want to review the data before you proceed.

PCB Visualizer has found a critical issue. You need to correct it now to avoid an exception later.

3. What do the messages mean?

There’s a full list of messages in the PCB Visualizer Help files (click [?] at the top right of the PCB Visualizer screen). The most common issues we find are:

Import failed.

Data not in Extended Gerber (RS-274X), or EAGLE .brd Version 6.

ACTION needed:

  • If the data is in Standard Gerber (RS-274D), PCB Visualizer cannot read it but our CAM systems can. Check that you have included an aperture table and place your order.
  • Otherwise generate Extended Gerber files from your CAD system.

No outline detected. Outline might be incorrect. Registration may be incorrect.

To find the outline, PCB Visualizer needs to be able to register the layers and then find a continuous rectangular box enclosing the PCB data. Typical reasons for the message may be:

  • Layers cannot be registered. Registering the layers is a statistical operation. It can be an issue if the layers are not registered in the CAD data and the layout contains only a few elements.
    • ACTION needed: Place your order: our engineers will register the data manually.
  • There is no rectangular box because:
    • There is no outline in the data.
      • ACTION needed: Upload a new data-set with an outline on at least 1 (better all) copper layers (see PCB Design Guidelines p.10) and place your order.The board is not rectangular or you have used corner-blocks
    • The board is not rectangular or you have used corner-blocks
      • ACTION needed: Place your order: if you have defined your outline clearly, our engineers will find it. We recommend that you do not use corner blocks as they can be ambiguous.
    • There is data outside the board outline on the copper layers
      • ACTION needed: Place your order: our engineers will find the outline and delete any data outside the board profile before manufacture.

No drill layers found.

This may be because you have not included a drill file in your data-set or because you have supplied a Gerber drill map instead of a drill file (see PCB Design Guidelines p. 14).

  • ACTION needed: Load a new data-set including an ASCII-formatted Excellon drill file.

Board buildup could not be determined. Board buildup may not be correct.

PCB Visualizer determines the buildup on the basis of the layer names and the content of the layers. If possible use our recommended layer naming conventions (see PCB Design Guidelines p. 4). Otherwise if PCB Visualizer has not assigned the layers correctly, use the Layer editorto correct the buildup. PCB Visualizer will learn the new assignment for future reference.

4. PCB Visualizer has put a red flag against my job: what should I do next?

Red flags show a serious discrepancy between order and the data. The first column shows the “required value” for the class selected for the order. The “measured value” in red shows what PCB Visualizer has actually found in the data. Some of the most common issues are:

Plating index lower than 0.4.

The plating index is a measure of the evenness of the copper thickness across the PCB . If the value is less than 0.4 there is a risk that some areas may be over-plated (copper too thick) and some under-plated (copper too thin). Click on the line to see the plating index image.

  • ACTION needed: For prototype boards this is not normally an issue. Place your order, though we cannot guarantee that the plating will be perfect. However, we recommend that you try to even out the copper density (usually by adding extra copper) before going into volume production. This will make a more robust end-product.

Minimum track-width and isolation distance.

PCB Visualizer flags any values less than the minimum specified for the chosen pattern class (see PCB Design Guidelines p. 6). Use PCB Checker to pinpoint the errors. You have 3 options depending on the number and type of the errors:

  • Modify the order to use a higher class. Note that this may increase the price of the board, and class 10 cannot be made.
  • Modify your design and upload a complete new data-set.
  • Our engineers may be able to correct a few minor errors. Place the order. If we cannot fix them, we will raise an exception.

Minimum annular ring.

PCB Visualizer flags any values less than the minimum specified for the chosen pattern class (PCB Design Guidelines p. 7). Use PCB Checker to pinpoint the errors.

Component holes.

Note that we allow some relaxation of the annular ring rules for obround holes (PCB Design Guidelines p. 9). PCB Visualizer always shows the minimum ring value. If the hole and pad are within the relaxed rules, proceed with the order.

Otherwise you have 4 options depending on the number and type of the errors:

  • Check that the hole size specified for the component is correct. If a smaller hole size will solve the problem, change the value and upload a complete new data-set.
  • Modify the order to use a higher class. Note that this may increase the price of the board, and class 10 cannot be made.
  • Modify your design and upload a complete new data-set.
  • Our engineers may be able to correct a few minor errors. Place the order. If we cannot fix them, we will raise an exception.

Via holes.

In many cases, annular ring issues on via holes can be resolved by our engineers. They either reduce the finished hole size or increase the pad sizes (especially on inner layers). They will raise an exception if the reduced hole size necessitates a more expensive class.

Note.

We assume that any hole of 0.45 mm finished diameter is a via hole which we can reduce. If you have component holes of 0.45 mm finished diameter or less, use the box in the Price Calculator marked “Holes <= may be reduced” to indicate the largest hole which can be treated as a via hole.

5. Why doesn’t PCB Visualizer display the slots and internal cut-outs in my job?

PCB Visualizer is a Gerber/drill analyser. Gerber data defines tracks, pads and planes. Drill data defines round holes. Slots and internal cut-outs are defined by draws, in different ways, sometimes on a mechanical layer and sometimes on a copper or legend layer. There is no reliable algorithm to recognize them automatically. However our engineers will recognize them during front-end data preparation. For the clearest way to define slots and cut-outs see PCB Design Guidelines p. 13.

If the slots and cut-outs are correctly drawn, place your order and our engineers will enter them into the production data. If you want to check them, use the “Pre-production check” function

6. PCB Visualizer hasn’t assigned the layers right: what should I do now?

Buildup is wrong

This can usually be avoided by clear layer naming conventions.

  • ACTION needed: Correct the build using the layer editor function and proceed with your order.

Layers mis-assigned

An unusual layout without a clear name may be mis-described.

  • ACTION needed. Correct the build using the layer editor function and proceed with your order.

PCB Visualizer has not recognised my profile/scoring layers.

PCB Visualizer can check and measure but it cannot interpret, especially if the mechanical data is stored in a document layer. Place your order: our engineers will normally sort this out.

PCB Visualizer has not recognised my blind/buried via layers.

There is no standard way to define these so PCB Visualizer cannot detect them. Define them using the Buildup Wizard and proceed with your order.

7. PCB Visualizer can’t read multi-job files.

I want Eurocircuits to build me a customer panel so I have put the 2 data-sets into 1 .zip file; but PCB Visualizer can’t show them properly. PCB Visualizer has been developed to work on single circuits. To check the data load each separately. Otherwise ignore PCB Visualizer, place your order and our engineers will panelise the files to your drawing.