By Mark Thompson | Published on: August 27, 2018
Greeting’s all. In this month’s column I will be writing once again about what makes up a great incoming dataset for PCB fabrication. However unlike my upcoming mini book on what are the necessary files for fabrication (because so many datasets today are incomplete or require additional clarification based on conflicting drawing notes).
This column will be dedicated to datasets with TOO much data and what problems and delays that causes.
Let me give you an example: IPC 2581. A consortium package that is all inclusive.( Includes the BOM and assembly information as well as design and Image output data in three formats) Please understand as long as there is no CONFLICTING information between the Image data ( and sometimes there is) this dataset can be used. Understand I am writing this from the standpoint of quick but accurate quotes of your PCB not the validity of a given dataset. What does that mean? It means we Love an IPC – 2581 output for manufacturing but for the purpose of a FAST and ACCURATE pre-quote analysis the additional files slow down the QUOTE.
Many Fabricators use Pre-quote software packages such as Insight or Integrator. Both are OUTSTANDING for what they are intended. A pre-quote design check to make sure obvious things like trace and space meet the copper weight defined and that a drill file exists and matches the drill drawing. However datasets such as 2581 or any dataset that includes MULTIPLE image outputs can slow the process down.
We have seen as many as 6 separate ODB++ outputs, some as an ODB folder, some as .TGZ files , some as ODB inside a .zip file all in the same dataset.
even though the datasets in theory should all be the same, input pre-quote packages must be edited so that only one dataset is checked. Multiple sets will stop the operation and ask for more user information, all of which takes time out of the quote process.
Along those same lines, as long as we are talking about things that will streamline the quote process let’s talk about FILE naming conventions.
Many Design systems have a default for file names as do drawing stack up templates. Most do not match exactly and if there are no z –axis layer designators on the file itself, sometimes it is difficult to tell what layer should be what.
Let me give you an example:
The Image data file template may call inner plane layers “GP1” for Gerber Plane 1 but your stack up may show the physical names of the layer functions. So “GP1” of your Image data may be called “GND” or “PWR” on the stack up describing the layer function more than the layer name.
Most of the time this is not an issue if you are providing an “. EXTREP” file or Extension representation file that describes the layer names vs. the stack up layer names.
Much like with MULTIPLE image datasets, incoming Pre-quote software packages will have trouble with identifying what layer is what and will pause for the operator to give the system more information so it can continue with an analysis.
At least as far as the pre-quote analysis is concerned , if the layer names and stack up layers can match and multiple datasets do not need to be culled prior to running the pre-quote software , the faster the pre-quote software works and the faster you get your quote.
The purpose of this column is NOT to suggest you do not use IPC – 2581 but to suggest for FASTER QUOTES you eliminate duplicate sets of data that slow down the quote process.
Understand neither of the examples I have given above are “show stoppers” that do not allow us to build the part but they do take additional edit time and if discrepancies exist, they must be addressed before fabrication.
In subsequent blogs I will go deeper into what makes a great output fab package.
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