PCB Checker highlights on screen the design rule (DRC) and manufacturability (DFM) issues which have been found by the underlying PCB Visualizer data analysis. It lists the DRC values of the PCB and provides some manufacturing data.
Automatic repair function.
From July 2015 PCB Checker also includes automatic repair functions.
When we prepare a job for production we run a number of routine automated procedures on our front-end engineering CAM systems (more). These procedures adjust the design data to our manufacturing tolerances. They are described in our data preparation BLOGS Eurocircuits Data Preparation – Single Image 1 and Eurocircuits Data Preparation – Single Image 2. We are now gradually introducing them as automated repair functions into PCB Checker.
The first automated repair function is now available to use. It repairs annular rings (outer and inner) on via holes where the copper ring remaining after drilling is below the minimum value for your chosen service. The repair function automatically reduces the via hole size, for example from 0.40 mm to 0.25 mm, so that the copper ring around the drill tool is sufficient.
Although the repair function is automatic, the user retains control. He can set the parameters within which it works to suit the needs of his job.
- Set the via hole size. Eurocircuits’ default specification sees all holes with diameter 0.45 mm or less as via holes. Under IPC rules via holes have no negative tolerance, so we can reduce their size, whether as here to increase the annular ring, or elsewhere to reduce the number of drill changes on a production panel and cut the cost of the PCB.Set the largest finished hole size which can be treated as a via hole in the box “Holes <= may be reduced” (in Figure 1).TIPS.(1). If you use components with leads which need a finished hole size of 0.45 mm or less, make sure that you enter here a value for via holes less than that required by the lead.(2). If you upload an EAGLE BRD file, PCB Visualizer takes over the identification of the via holes automatically. There is no need to change the value in the “Holes <= may be reduced” box.
- Set the smallest finished hole size allowed. Enter the value in the box “Smallest final hole” (in Figure 1).TIP.Set this parameter to default 0.25 mm to meet the lowest cost pooling service specifications. Smallest final hole size 0.15 mm will increase the board price slightly. We can produce PCBs with 0.10 mm finished hole size but these are non-poolable so more expensive. A more cost-effective option is to accept a smaller annular ring of 0.10 mm by changing the PCB classification to 8C or 8D.
How to use PCB Checker.
Once you have got a price and uploaded your data you can proceed immediately to place your order. If there are any data issues, our engineers will resolve them and where necessary ask for your approval using our Pre-Production Approval (PPA) procedure.
However, we recommend that you allow a few minutes for PCB Visualizer to analyse your data-set and identify any issues which may delay production. Check the PCB Visualizer column on the Shopping basket page. If there is a green tick, there are no data issues. Place your order confident there should be no delays. If there is a red flag, there are potential issues which may delay delivery. Use PCB Checker to check them out.
Check DRC issues
1. Click on PCB Visualizer, then on the PCB Checker tab top left (Figure 3).
2. The new screen will show the PCB Checker report for your data (Figure 4).
The report includes:
- DRC information
- Fault view
- Board build-up
- Bird’s Eye View of the PCB
- Detailed View
- Commercial Summary
- Description of the issues found
If you are accessing the PCB Checker report after the job has been through data preparation (for example as part of the Pre-Production Approval process) the default data shown top right will be Production data. Click on the box and select Customer data to see the DRC issues.
3. The DRC report top left (Figure 5) shows:
- In the first column headed Layer: the DRC categories per layer (track width, isolation and annular ring).
- In the second column headed Required: the minimum value required by the chosen service (here STANDARD pool).
- In the third column headed Measured: the actual values found in the data. A red figure indicates a serious issue.
- The fourth column under the red flag: critical DRC issues which will prevent production of the job as it stands.
- The fifth column under the yellow triangle: non-critical DRC issues, typically small deviations from the requested values which may be due to rounding errors. These will typically be corrected by our engineers while preparing the data for production.
- Last column under the spanner: DRC errors which can be auto-repaired.
4. Now click on Outer layer trackwidth/Top copper.
This opens the Fault view (Figure 6):
- The top section shows the description of the issue and the nature and number of cases: here 1 critical trackwidth issue on the top copper layer.
- Current issue provides a stylised image of the issue.
- The text gives the trackwidth value as Measured in the data and as Required by your chosen service.
- The figures at the bottom of the screen allow you to step through each case in the Bird’s Eye and Detailed Views.
The yellow dot shows the location of the track issue indicated at the bottom of the Fault view (Figure 7). The red rectangle indicates the area of the board in the Detailed View (Figure 8).
In this case no auto-repair is currently available. Either change your data or change the board classification from 6C to 7C (small price increase). To do this, click the Measured radio button in the Remarks pane –in Figure 9).
5. Click next on Outer layer isolation distance/Top copper (Figure 5).
Follow the same procedure as for the trackwidth issue. Again there is currently no automatic repair solution.
A non-critical, yellow triangle issue can usually be solved by our engineers. Typical small errors occur between pads and copper fill areas (Figure 10), as copper fill programs often do not take proper account of DRC rules or are subject to rounding errors. Our engineers can fix these by selecting all copper fill areas and slightly reducing them.
6. Click next on Outer layer annular ring/ Top copper (Figure 5).
Here we have 22 critical red-flag errors. The annular rings are 0.025 mm against the service specification of 0.125.
This is shown in the Fault view (Figure 11):
- Top section indicates 22 red-flag errors.
- The Current issue window shows the dark grey pad and track and the light grey hole. The solid yellow circle shows the “calculated pad”. This is the minimum circular area required to accommodate the drill hole diameter and the annular ring. Most via holes have circular pads, so the calculated pad is the same as the original pad. If the via hole is placed in a non-circular pad, then the two may not be identical.
- The text gives the values for the measured and required annular rings, the tool and hole diameters, and the calculated pad diameter.
- The figures at the bottom of the screen allow you to step through each case in the Bird’s Eye (Figure 12) and Detailed Views.
In this case, no auto-repair is possible as the maximum via hole size is defined in the “Holes <= may be reduced” box (in Figure 1) as the default 0.45 mm.
However, the holes are in fact vias. Change the value to 0.50 and all 22 are repaired. Fault View has changed to reflect this (Figure 13):
- The top section now shows 22 repaired cases
- The light grey area in Current issue shows the original hole and the dotted yellow circle the new tool diameter.
- The text now shows an extra column with the values for the new annular ring and the new tool and final hole diameters.
The Bird’s Eye View (Figure 14) now shows the repaired vias in green (the yellow dot locates the via shown in the Fault View).
(1). If you use components with leads which need a finished hole size of 0.45 mm or less, make sure that you enter a value in the “Holes <= may be reduced” box less than that required by the lead.
(2). If you upload an EAGLE BRD file, PCB Visualizer takes over the identification of the via holes automatically. There is no need to change the value in the “Holes <= may be reduced” box.
You can also set the smallest finished hole size allowed. Enter the value in the box “Smallest final hole” (in Figure 1).
If we set this to 0.35 mm in our example, we find that we again have 22 critical, red-flag errors as the minimum annular ring is now 0.100 mm while the specified value is 0.125 mm (class 6C). Click on the Outer annular ring Measured value in the Remarks pane or change the value in the PCB Configurator Technology pane. The board now meets the requirements of Technology class 8B.
Set the Smallest finished hole parameter to default 0.25 mm to meet the lowest cost pooling service specifications. Smallest final hole size 0.15 mm will increase the board price slightly. We can produce PCBs with 0.10 mm finished hole size but these are non-poolable so more expensive. A more cost-effective option is to accept a smaller annular ring of 0.10 mm by changing the PCB classification to 8C or 8D as in the paragraph above.
The Design for Manufacturability (DFM) tab has 4 sections.
- Plating index value. This measures the uniformity of the copper across the PCB and hence the evenness of the finished plating. See a full description here. A blue colour shows areas of under-plating and red of over-plating. For the most part this is a guide to best practice, but if the plating index falls below 0.4 then you need to take steps to improve the balance. If you combine several different circuits on the same delivery panel it is particularly important to check the copper balance to make sure that all the circuits will be properly plated.
- Area of surface-mount pads on the top and bottom of the PCB so that you can calculate how much solder-paste will be required.
- Potential fiducials. This is information requested by our assembler customers. From time to time they need to mount tight-toleranced components where they need fiducials for accurate alignment but there are either no fiducials included in the design or they are damaged or otherwise unsuitable. This means that they need to find pads which are free of soldermask and not connected or drilled.
- Copper free of soldermask. This is needed for accurate calculation of the cost of Chemical Nickel/Gold (Che Ni/Au) surface finish.
If anything is unclear or you have any questions contact our online support team by clicking the green Support tab on every page of our website or email us at firstname.lastname@example.org.