Steps to review a PCB Layout - Part 2

We have seen some of the review steps in the previous PCB Layout review article. Let us continue to look around the points to be reviewed in PCB Layout. You can use this below points as a kind of checklist during your PCB Layout review.

1. It is always a good practice to have Part number printed on the PCB. If it was required, ensure that the same has been included during the PCB Layout activity.

2. In-circuit testing (ICT) requirements are very critical. Ensure that all the critical nodes to most of the nodes are covered in the testing. Near to 100% coverage is what most of the projects target.

3.  One of the mistakes which happen are the clearance near the mounting holes for screw requirements. Verify the screw head size and review such that there are no issues.

4. While PCB Layout engineer do run the Design Rule Check (DRC), it is always preferred that reviewer runs one on his own. During the DRC check, ensure that all the constraints are set.

5. One of the mistakes reviewers do is that they take up the task of review without having the clear background of the project. It is always important that reviewer verify keeping specifications in hand and most importantly review to ensure that board meets required standards.

6. Ensure that required creepage and clearance are maintained in the PCB Layout.

7. While verifying the silk screen, ensure that all pin marking and reference designators are visible even component is assembled on the board. If the board is very dense, most of the designers eliminate silk screen. Reviewers have to keep these points in mind.

8. Ensure in the PCB Layout that Analog and Digital grounds are combined at only single point. They should not cross over at multiple places. 

9. A reviewer must always have DFM guidelines handy. PCB Layout should always be reviewed from that perspective. Different manufacturers have variation in DFM and it is some what a task for reviewer to understand the fab house and their requirements. This shows the extent to which the review engineer must think.

10. Ensure that the PCB fits into the mechanical that was designed. For this create a step file for the PCB and integrate with the Mechanical. While designers do verify this aspect, it is good to provide inputs to Mechanical designers through out the PCB Layout process.

11. Ensure that all the heights of the components entered into the PCB layout are correct.

12. If the design demands any heat sink requirement, it is always important to assess the type of heat sink and mounting type on the PCB. Enough room around the heat sink must be present such that surrounding the components doesn't have any issues.

13. Before releasing any PCB Layout, it is always important to verify the Gerber. Gerber verification is the last minute effort by designers to catch any errors.

14. A critical point in the PCB design is to ensure that the traces are having enough width to carry currents required for operation. Reviewer has to understand the copper width used and use PCB calculators to verify the current carrying capability.

15. Ensure that none of the PCB routing happens near to and underneath the crystal on the board. Also, ensure that crystal and associated components are as close as possible to relevant chip.