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PCB Pitfalls

Here are some of the errors we see that cause manufacture delays or worse.

Missing layers:

Most manufacturers need Gerber files to manufacture and these are easily generated in DesignSpark.

Using the Output tab, choose Manufacturing plots, choose Gerber and run.

title

Be mindful when sending files to your manufacturer. We need them all to have the full picture.  The types of errors we see are

1)      The files are just missing.

2)      The file has no date.

If files are missing we have to wait until you send them, thus delaying your build and your project.

Gerber File extensions needed for manufacture are:

Layer

File ext in DesignSpark

Top

.GBR

Inner

.GBR

Bottom

.GBR

Top Mask

.GBR

Bottom Mask

.GBR

Top Silk

.GBR

Bottom Silk

.GBR

Top Paste

.GBR

Bottom Paste

.GBR

Board Outline

.GBR

Drill

.DRL

Drill Format

Another common error, is not providing the drill format provided in or with the drill file.  This setting is provided within the Gerber Outputs in DesignSpark. 

Here is an example of what this information looks like:

title                                                                   

Overlapping Drills:

titleOverlapping drill holes can cause problems during manufacture.  Drills bits often break during the drilling stage which can cause physical problems. Also, small pieces of material can remain, creating voids in the plated hole.  This can lead to additional costs, delayed manufacture or potentially bad boards.

 




Solder Resist Pads:

titleOften we see designs with missing pads and extra pads on the solder mask layers. Generally, missing pads are design errors.

Another pad complaint is extra pads.  This can happen when the designer uses the same components in different layouts and imports the solder resist for the component. Due to the different layouts extra pads may be placed in the layout which can cause exposed traces, plains etc.

These errors are not found at Design For Manufacture (DFM) checks and could make it to the final PCB.  This might affect the functionality of the PCB.

Avoid Via-In-Pad

Often components packages such as BGAs & QFNs are designed using via in pads. The trick in prototyping is to try and avoid them if at all possible.  Via in pads can pull the solder away from the component to the other side of the via.  So the smaller components may not have a solder connection, the larger ones may have a bad connection and the balls on BGA may simply disappear.

title

If you really need the via in pad, make it as small as possible to reduce the pull, cover them with solder mask*.  Another note of caution, air can get trapped if the other side of the via is capped by solder mask.  The air will be ejected during the soldering process. The air can affect the solder and result in bad joints.

 *Be sure to tell your manufacturer that you want the vias masked as often they remove that mask unless it’s requested.

Provide Readable Documentation with Good Silk-Screening

titleThe silkscreen layer doesn’t have any electrical function but it is crucial in ensuring the assembly plan is understood and easy to follow.  Badly sized text, uncommon symbols can be detrimental during the build and when troubleshooting.

It is important to properly mark components with polarity. For ICs,  pin 1 and orientation is crucial to specify.

Calling all DesignSpark users, please tell us about your experiences and any pitfalls. Tweet us at @MintTekCircuits or @DesignSparkRS, or email me directly at siobhan@mint-tek.com. As a regular blogger, I’m always looking for key learnings to share with my audience.

At Mint Tek Circuits we use a global panel of proven PCB manufacturers to get the best technology, at the best price, in the best time. We work closely with the DesignSpark community to create a simple supply chain for design engineers.

Experience our online PCB Quote Calculator for yourself 

My first science hero(ine) was Marie Curie and I've always been fascinated by technology and inventors. I've spent my working life trying to make electronic developers' lives easier. Mint Tek is the culmination of that, a place where I hope that gives legs to your brilliant idea and helps you find out if it works and fits into our amazing world.

27 Jun 2016, 9:08

Comments

February 3, 2020 13:40

Hi,
Its 2020 and I am about to start my journey with Designspark - much depends on it....just wanted to let you know you advice is timeless. Thanks again.

0 Votes

[Comment was deleted]

July 21, 2017 08:05

thanks..for your huge contribution to the electronic world..

0 Votes