Few Questions

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   I am testing your software. First impression is really good. I have few issues though.
3D generated model of SOP package does have indentation mark (white circle), but 3D model of SOIC package does not have it. Is it done intentionally?
There is no automated way to draw footprints for PLCC2 package (LEDs).
And most importantly, I have yet to find a component for which manufacturer recommended footprints and your calculated footprints match. They are always slightly different. I have tried different manufacturers and different types of components. For example, the last part that I have tried was RTC clock from Maxim (package no. - W16#H2). Manufacturer suggests to draw footprints this way: http://pdfserv.maximintegrated.com/land_patterns/90-0107.PDF, but when I describe the package in your program using these drawings (http://pdfserv.maximintegrated.com/package_dwgs/21-0042.PDF), I don't get the same footprints. Why? Should I follow manufacturers' guide?

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JJonas Members Profile Send Private Message Find Members Posts Add to Buddy List Advanced User Joined: 21 Apr 2014 Status: Offline Points: 113	Post Options Post Reply Quote JJonas Report Post Thanks(1) Quote Reply Topic: Few Questions Posted: 22 Apr 2014 at 5:47pm
	I am testing your software. First impression is really good. I have few issues though. 3D generated model of SOP package does have indentation mark (white circle), but 3D model of SOIC package does not have it. Is it done intentionally? There is no automated way to draw footprints for PLCC2 package (LEDs). And most importantly, I have yet to find a component for which manufacturer recommended footprints and your calculated footprints match. They are always slightly different. I have tried different manufacturers and different types of components. For example, the last part that I have tried was RTC clock from Maxim (package no. - W16#H2). Manufacturer suggests to draw footprints this way: http://pdfserv.maximintegrated.com/land_patterns/90-0107.PDF, but when I describe the package in your program using these drawings (http://pdfserv.maximintegrated.com/package_dwgs/21-0042.PDF), I don't get the same footprints. Why? Should I follow manufacturers' guide?



Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718	Post Options Post Reply Quote Tom H Report Post Thanks(1) Quote Reply Posted: 23 Apr 2014 at 6:45am
	Answers - The metric pitch SOP has a polarity dot and the imperial pitch SOIC has a pin 1 side body chamfer. The Library Expert follows the IPC-7351 standard component packages. The PLCC2 LED is not in the standard yet. However, you can use any 2-pin package like "CHIP" and enter the body dimensions and then select the "Footprint" tab and enter the mfr. recommended pattern dimensions. In the CHIP component family you can also select LED CHIP. You can also use the "Footprint Designer" (FP Designer) to create any mfr. recommended footprint. If you don't like the proven IPC-7351 auto-generated footprint you can always use the "Footprint" tab for every component family or use FP designer to create pad stacks and place then where you want them. We do promote the use of the mfr. recommended pattern for all component packages that are not in the IPC-7351 standard. The Library Expert is very versatile, you just need to build some parts using the various options. In the V2014.01 release (coming out later today) there is also a PADS Layout p/d file translator. You may not think this is important, but later this week "Parts on Demand" (POD) website will open and it will have unique complex package footprints available for download in PADS p/d ASCII format and there will be a filter that the data passes through to allow you to change outline widths and on/off switch for all outlines. POD will also contain millions of mfr. part numbers available in FPX format to save you the trouble of entering in all the component dimensions and physical and logical attributes in the FPX file. PCB Libraries, Inc. is investing most of our resources into library content to eradicate library construction globally for all CAD tools. Customers will be able to "Search > Find > Download > Import" FPX files into Library Expert and if you can't find the mfr. part number you're looking for you can request it and either the electronic community will upload it to POD or PCBL will upload it or you can create it and upload it to share with everyone else. Every Footprint in the world only needs to be created once by someone and shared with everyone in a neutral software format that can be outputted to every CAD tool in the industry. There are 500,000 different component packages and 50 million mfr. part numbers. Eventually all of them will be on POD.
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JJonas Members Profile Send Private Message Find Members Posts Add to Buddy List Advanced User Joined: 21 Apr 2014 Status: Offline Points: 113	Post Options Post Reply Quote JJonas Report Post Thanks(1) Quote Reply Posted: 23 Apr 2014 at 12:56pm
	Thank you for your extensive answer. 1. I can now see that body chamfer. I would prefer to have a white dot marking as an option for SOIC (and any other relevant packages) as it is more visually distinguishable. Maybe you could include this option in your future releases. 3. I guess it is not a matter of if I like mfr. recommended pattern or not. My provided example states "LAND PATTERN COMPLIES TO: IPC7351A". I am interested how mfr. can get different footprints if it follows the same standard as you do?

Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 23 Apr 2014 at 5:33pm
	V2014 has a White Dot for silkscreen polarity. V2014 will be released tonight. For Standard Packages use IPC-7351 land patterns. For unique one-of-a-kind package use the mfr. recommended pattern.
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