Footprint / Land Pattern Naming Convention
Printed From: PCB Libraries Forum
Category: Libraries
Forum Name: Footprints / Land Patterns
Forum Description: [General or a CAD specific issues / discussions]
URL: https://www.PCBLibraries.com/forum/forum_posts.asp?TID=29
Printed Date: 22 Nov 2024 at 2:26am
Topic: Footprint / Land Pattern Naming Convention
Posted By: Artwork Master ITALY
Subject: Footprint / Land Pattern Naming Convention
Date Posted: 18 Mar 2012 at 10:12am
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Hi, in the document "PCB Design Optimization Starts in the CAD Library.pdf" at page 21 it is defined a 3 letters of code for distinguish each electronic Manufacturer of components. Is it possible see the actually list of them before the program of building the decals will be ready? (probably before the date of May 1 2012) so we can contribute to enhance this list! |
Replies:
Posted By: Tom H
Date Posted: 18 Mar 2012 at 10:48am
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Please send me a private message "off-line" or if you know my email address and I will send you the list of Component Manufacturer's and the 2 - 3 character code. The creation of the 2 - 3 character suffix is still in the works, so if you want to help define the abbreviations that will be great too. The new PCB Footprint Calculator will have the list of component manufacturer's built in to automate the Footprint (Land Pattern) Name. |
Posted By: Tom H
Date Posted: 18 Mar 2012 at 11:14am
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We are currently working on the "Mil Unit" Footprint (Land Pattern) Naming Convention document. Both the Mil and Metric Land Pattern name documents will be posted soon. There are many updated documents that will be posted soon. - Component Manufacturer list with the completed abbreviations - Mil & Metric Land Pattern Names - Mil & Metric Padstack Naming Convention - Mounting Holes & PCB Hardware - Footprint Zero Component Orientations - Reference Designators But the largest collection of Footprint (Land Pattern) creation data will be in the "PCB Library Construction Guidelines" section - http://www.pcblibraries.com/forum/pcb-library-construction-guidelines_forum30.html" rel="nofollow - http://www.pcblibraries.com/forum/pcb-library-construction-guidelines_forum30.html The primary reason for adding "mil units" is that PCB Fabrication, CAD Vendors and most companies that do PCB layout have not transitioned to the Metric measurement system. There is not 1 PCB Fabrication shop in the USA that prefers Metric Unit Gerber data, Drill Data, Drawings, Laminate Stack-ups, Copper Weight or any aspect of fabrication PCB construction. Some tolerate Metric Units, but behind the scenes they convert Metric Units to Mil (Inch) Units. As PCB Designers, we were always taught DFM (Design For Manufacturing) and if the PCB manufacturer's don't want Metric Unit data then PCB Designers are not designing for DFM. The new "PCB Footprint Expert" will default to Mil Units for library construction, just like every CAD vendors tool set. The User can switch to Metric Units to insert component dimensions and then switch to Mil Units for Footprint creation. Every value of the Footprint features will be rounded off in 1 Mil increments and Footprint & Padstack names will be Mil Units. |
Posted By: Matija
Date Posted: 23 Mar 2012 at 10:26am
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Hello Tom, this is the biggest disappointment that I ever heard: Predominant measurement system to be Mil units for a library service that is supposed to be used world wide and be truly global. There are two main reasons I am disappointed. The one is "political" the other is "technical" The political one: Please take in account that the there is more to the world as only continental US. When I read "... and most companies that do PCB layout have not transitioned to the Metric measurement system. There is not 1 PCB Fabrication shop in the USA that prefers Metric Unit...", I am also wondering did you ever realize that there are people who never heard of Mil Units. Our PCB producre here in Europe does everything in Metric. We set up rules in metric, design in metric, produce and assemble in metric, etc... I could just say the same phrase the other way around "...... and most companies that do PCB layout have not transitioned to the Mil Units measurement system. !!!" As much as I respect your work and your idea, this unit choice is catastrophic, and shows a lot of "close mindedness" on the world as a global. And now the technical point: You can always convert a metric unit back to a Mil unit without loss of precision. The other way around it is not the case, due to rounding errors. Please reconsider your choice and since PcbLibraies is menat to be a reference point for everyone designing libraires, force the use of both with preference to the metric unit as native unit. Regards Matija |
Posted By: Tom H
Date Posted: 23 Mar 2012 at 11:31am
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There
is a misunderstanding about the Default Units. We are creating a
"Dashboard" that appears when the user opens the PCB Footprint
Calculator that allows you to pick what Measurement Units you want the program
to default to. We have implemented provision options in the new PCB Footprint Calculator to allow the User to -
o Always default Land Pattern and Padstack Names to Metric
units o Use Metric Land Pattern and Padstack Names when using
metric units o Use Mil Land Pattern and Padstack Names when using mil
units The globally the CAD Vendors default units are mils.
There are PCB designers worldwide that are doing PCB layout in mil units. There
are PCB manufacturers worldwide (especially in China and India) that prefer mil
units for PCB fabrication. Your argument is not with PCB Libraries, Inc. You need to
take it to the PCB fabrication shops and convince them to transition to the
metric unit system. Everywhere I look in the USA, PCB designers are being held
back from transitioning to metric because their PCB fabrication shops prefer
mil unit data.
The
free PCB Footprint Calculator that will become available on May 1, 2012 will
have the ability to save component dimensions and manufacturer attributes
(including datasheet web-links) in an .fpx file. You can upload your .fpx files
to our server and we’ll sell them for you, giving you a 25% lifetime royalty.
The library customers will have a “PCB Footprint Expert” that will import .fpx
files and auto-save the component manufacturer's data to the customers master
.fpx library on their server and auto-generate the PCB library part using their
personal preferences for Silkscreen & Assembly line widths, Ref Des sizes,
Footprint Rotation (IPC, IEC, EIA), Origin, Measurement Units, Land
Pattern and Padstack Name (there are too many personal preferences to list them
all) and export the PCB library part to their native CAD tool format. There
will be hundreds of thousands of library parts available on a web-based Vending
Machine in a neutral format and the End User can output whatever
"preferences" they choose. What's
catastrophic is the lack of commitment from the PCB fabrication industry to
transition to the metric unit system and they're holding back "Electronic
Product Development Automation". If all PCB designers would ban together
and only provide their manufacturer's metric data then the fabrication shop
might transition. Let's all work together to migrate the entire electronics
industry to metric units. However, there are PCB designers who are near retirement
who have no intention of ever learning the metric unit system. There are
service bureaus who must use Imperial measurements because their customers
demand it. We are
creating a new tool and service that will provide the largest amount of library
content in the world. We hope to cover all bases to make everyone productive. |
Posted By: Dale
Date Posted: 21 May 2012 at 7:05pm
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Re units, personally I think the decision to formally allow mils will delay the ultimate transition to metric by many years, extending the dual-units pain and cost to yet another generation of designers. Re land pattern design and naming: The footprint calculator seems to assume that there will always be just one data sheet from which the component dimensions are transcribed - and the naming allows us to identify THE manufacturer. i.e. single sourcing. Maybe single-sourcing is common in some industries/fields, but in the 30+ years I have been involved in the electronics design and manufacturing industry it has been the exception. Engineers have always had to get special permission to design in a single-sourced part. Is the footprint calculator making any concessions to the needs of us who must consider multiple very similar packages when designing footprints? |
Posted By: Tom H
Date Posted: 21 May 2012 at 9:09pm
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Hey Mate, PCB Libraries, Inc. is not in the business of telling customers what measurements units are best for them. And we do not support single vendor for component selection. Rather we support multiple vendor sources for every electronic device used in PCB layout. That's why we are creating the world's largest PCB Library Vending Machine based on component manufacturer's part numbers for easy search, find, cross-reference and download. However, or database will offer both mil and millimeter based library parts and our best guess is that the mil based library parts will out sell the metric library parts for the next 10 years. I applaud your effort for the electronics industry to transition to the metric measurement system, but you need to take your case up with every PCB fabrication shop in the USA. They ALL prefer mil unit fabrication drawings and Gerber data and until they transition the PCB designers in America will never transition. I would also take a case up with the component manufacturers who call there chip components named after mil units - 0201, 0402, 0603, 0805, 1206, etc. The component manufacturers need to stop the proliferation on the mil unit system, especially in their marketing of imperial unit component names. What about all the PCB fab material providers like Isola, Rogers and others who predominately create mil based fabrication materials for the PCB fabrication vendors. American fabrication has now successfully introduced and transitioned Chinese fabrication shops to mil units. Yes, we taught the Chinese workers how to work in mil units. How about Polar Instruments with their impedance calculator defaulting to mil units for PCB fabrication impedance control. Or what about all the CAD vendors who create CAD tool installations using mil units as their default units. OK, I mentioned PCB fabricators, material providers, component manufacturer's, impedance control calculations and CAD vendors. You should take up your position with them and when they convert we'll gladly convert with them. PCB Libraries, Inc. has been on the metric bandwagon for the past 10 years and nothing has changed. Our tools support the metric measurement system 100% and we are greatly advanced in the metric unit system. It just so happens that our tools are very mil unit friendly too. I'm not sure that our efforts will postone the transition of anyone to the metric measurement system. It's the other vendors that are responsible for the delay of standardization to a single measurement system. Transitioning to a universal measurement system would greatly simplify our job, our tools and the global electronics industry, but it's not reality (yet).  |
Posted By: Dale
Date Posted: 21 May 2012 at 11:42pm
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Oops, looks like I hit a raw nerve - nothing personal was intended. In principle I agree with everything you say, however I have much less influence than you. I have long noted that PCB Libraries has been on the metric bandwagon and have privately applauded those efforts. What I was perceiving was the Imperial stalwarts grinding you down. Slightly off the subject - I wish more US software vendors would look at the Windows Regional settings and use that as the default. Sadly Adobe and Mentor (to name two major vendors whose software I use) think everyone prefers Imperial by default; you want something else?, then you chase down the settings if they exist. Not very user friendly in that regard. |
Posted By: Tom H
Date Posted: 22 May 2012 at 9:20am
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I joined IPC to help them transition the PCB industry from Imperial Units to the Metric Unit system. Every Power Point presentation I gave in the past 10 years only contained metric units. The 1st Land Pattern Calculator we created only supported metric units for the first 5 years of it's existence. I pounded the industry with a call to transition publically speaking at 5 - 7 conferences every year for 10 years. As the president of PCB Libraries, Inc. I surrounded myself with everything metric and I burned all knowledge of the Imperial unit system. Then Valor took over the tools and sent me all over the world to train and teach others. But then Mentor Graphics came along and took over Valor. I worked at Mentor and tried to convince the developers that all CAD tool installations should default to metric units and that all PCB training classes should be taught using metric units. My recommendations fell on deaf ears and then I was fired. Then I re-entered the PCB design workforce and tried to find a company to work for that adopted the metric unit system and that task was impossible. I submitted 50 different job applications into companies looking to hire PCB designers but all of them were using the Imperial unit system. So I eventually took a job with CADParts Consulting service bureau for several DOD companies and every library part I create and everything I design is in Imperial units because that is what their customer's want. I can't fight anymore to be the poster boy for the metric measurement system. I know in my heart that metric units are far superior to Imperial units for PCB design layout, but I cannot die on that hill simply because PCB fabrication won't transition. For 10 years under PCB Libraries, Inc. I was in a metric world, but no other PCB vendors were. I tried to help IPC transition the industry from Imperial to Metric units, but IPC failed to communicate the transition to PCB fabrication shops. As a PCB designer, everything we do must be for DFM (Design For Manufacturing) and all the manufacturer's preach mil units to all their customers. The transition will only take root when PCB fabrication prefers metric units. And IPC, JEDEC, EIA, NIST, ANSI, IEC and all the world standards stand helplessly by the metric unit system while PCB fabrication ignores their call for unity and standardization under the umbrella of a single global unit system. |
Posted By: Nick B
Date Posted: 22 May 2012 at 10:05am
| Dale, we're building an infrastructure to help anyone facilitate an "easy" transition to metric. Our vision remains 100% intact, only we're using a very different strategy now. We have to rebuild everything from scratch (software, apps, site, etc), so it goes without saying we have to deal with a bit of a setback. However, long term we want to support both systems and let the industry decide when it is ready for transition. Whenever that is, we'll be there for 100% support. |
Posted By: matthelm
Date Posted: 10 Jul 2012 at 2:37pm
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My 2 cents on this issue. These are my opinions only, and you can take or leave them as needed. First, design the part in the units the part was designed in. MUCH less likely to have errors in the part. Computers are GREAT at math, let them do all the conversions for you. If your tool can not handle the conversions, get a new tool, that one is out of date. Second, do not round! I worked at a place that said to use 100% metric, but only show 1 place decimal. One of the first parts I worked on was a "inch" based part, and had the pins at .1 inch, but the drawing showed 2.5mm. 2.5 is NOT equal to 2.54, and NEVER will be!!! DO NOT ROUND!!! If they would have left the drawing alone (in inches), build the part in inches, the part would have worked perfect! (tool would have put the pins at 2.54 with ease) Luckily I had the old drawing, and an ECO was created to fix the drawing. Third, do not use old rules, as most of them no longer apply. Example when generating Gerbers: The old rule of 2.4 (inches, can you tell where I'm from?) data format. This was mainly done to keep file sizes small. Does it matter if a file is 10K or 1M any more? Not really. Plus if all you add is a bunch of zeros, zipping will take care of almost all of the extra. I do think we need to switch to 100% metric, but 1 inch does equal 25.4mm which equals 1000 mils, so you can convert all you want, but I'm going to let the computer do the work! |
Posted By: adaptive
Date Posted: 04 Oct 2012 at 1:42pm
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Hello to All, This is very interesting topic. I support metric PCB design 100% but I struggle to find a single PCB shop in US or Canada that is truly geared up for metric PCB fabrication.
If anyone knows a metric PCB shop please let me know.
Thank you,
Ed.
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Posted By: Tom H
Date Posted: 04 Oct 2012 at 2:11pm
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Ed, I'm with you 100%. I do all my PCB layout in Metric but I can't find 1 PCB manufacturer in the USA who is metric compliant. All layer stack-ups, impedance control data, differential pair demensions (EVERYTHING) that comes out of USA manufacturer's is in Mil Units. I attend IPC Designer's Council Meetings and IPC Symposiums and PCB West/East conferences, IPC APEX conferences, DesignCon, SMTA and ALL the speakers from ALL the manufacturer's speak and teach in Mil Units. I love to hear them teach PCB designers how to solve complex metric fine pitch BGA solutions using Mil Units. I just got an email from the Orange County IPC Designers Council that Charles Pfeil from Mentor Graphics is the next speaker on fine pitch BGA's 0.65 mm, 0.5 mm and 0.4 mm. I worked with Charles and all he talks about is Mil Units. So if you want to learn how to solve Metric Pitch BGA's using Mil Units, this meeting is for you. When I was in China talking to employees of PCB manufacturer's they told me that they just learned a NEW measurement system "Mil Units". They told me that American educators taught them. I can't believe it! |
Posted By: jameshead
Date Posted: 05 Oct 2012 at 12:23am
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UK schools and Universities teach and use the SI system and metric. In the real world when I joined Graphic in the mid nineties there was a mix with most UK companies giving us gerber data in "thou" (as we call "mil" over on this side of the pond), excellon data which could either be also in thou (good) or metric (not ideal but the CAM software could snap drill hits back to pad centres) and the fabrication drawing which was typically output in HPGL from Autocad or similar, all in metric with metric drill sizes. European and Japanese companies used metric exclusively and North American ones used imperial exclusively. To be honest it didn't matter one jot what the customer supplied us with - we'd accept both, work with it, and if we needed to contact the customer we'd talk to them in the units they'd use. |
Posted By: adaptive
Date Posted: 05 Oct 2012 at 5:29am
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Tom, Thank you for a quick reply. I find it sad that we are embracing a less superior system onto Chinese fabrication houses.I have been desiging in "mil" system for years and always struggle with the grid when it comes to metric BGA parts. Now I am trying switch over to metric because I see how easy it is to stay on grid when it comes to BGA fanout. However, your point from earlier posts is well taken, DFM is what is most critical. What is design good for if you can't manufacture it?
Can you briefly explain to me when you layout the PCB designs in metric, are you using just metric routing grid and imperial drill holes (for domestic US fab shops) , or are your design fully in metric inlcuding the drill holes?
The meeting on 0.4mm BGA pitch using "mil" would we be something worth seeing.
Can you tell me date and time for the meeting and is it possible to join online?
Thank you,
Ed.
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Posted By: Tom H
Date Posted: 05 Oct 2012 at 8:25am
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Mixing PCB Design
Layout units will compromise perfection every time. PCB Design perfection
starts with building CAD library parts and quickly moves to part placement, via
fanout and trace routing challenges. Outputting data for machine production can
be extremely complex or very simple based on the PCB Design Layout units that
were used throughout the PCB design process. One of the
single most important, but sometimes overlooked or taken for granted, aspects
of the electronics industry is the PCB Design Grid System. From the 1960’s
through the 80’s the primary PCB design grid system used Imperial units. All
PCB design features and grid layouts were in 0.001” (1 mil) increments and
everything was symmetrical and evenly balanced. Then in 1988 the world
standards organizations banded together to agree that the metric unit system
was superior for solving PCB design development. The first signs of this
transition started appearing in the 1990’s in component manufacturer’s datasheets
and the JEDEC component packaging dimensional datasheets, which were once
entirely based on Imperial “inch” units, where slowly converted to metric
units. IPC, a world
standards organization, proposed a base value of 0.05mm for the “PCB Design
Grid System”. And the process of getting all features in the PCB design back “On-Grid” was started. However, this was met by great resistance in the USA. Some
American PCB designers, manufacturing companies, mechanical engineers and EE
engineers are still fighting the transition process. The transition from
one unit system to another introduced chaos in the PCB design industry because
PCB designers were forced into using two different unit systems during the
transition period. The CAD vendor’s way of coping with the transition was to
introduce a “Gridless Shape Based” auto-routing feature that provided the PCB
designer a solution for working with both metric and imperial unit pin pitched
land patterns. New technical terms were introduced like “Off-Grid” or “Gridless”
and “Shape Based” routing solutions. This concept was entirely based on the
fact that PCB design rules are the primary factor and the PCB designer’s
objective goal was to adhere to the rules regardless of how irregular the land
pattern features were. Some CAD library parts have an inch based pin pitch and
some have a metric pin pitch. The PCB design grid system was chaotic and
working in a gridless environment presented new challenges for PCB designers as well as CAD vendors. The main impact of the gridless system for PCB layout is the fact that trace routing computations is so granular that it consumes far more memory and CPU processing. The gridless system has tens of thousands of additional options to commutate and actually slows the auto-routing tools down. It also makes it extremely difficult to cleanly manually route traces in-between the center of two component leads or vias. The "Enterprise CAD Tools" such as Mentor's Expedition, Zuken's CR-500 or Cadence Allegro are an exception to this rule as they handle gridless computations extremely effienct. All the trace / space rules are defined and that's the only thing that matters for PCB manufacturing. And Expedition has trace / space centering too to add the "Manual Route" look to a PCB layout. However, 90% of all PCB layout companies cannot afford the cost and learning curve of an Enterprise CAD tool. As a matter of fact, most PCB designs are done in CAD tools that cost less than $4,000 USD. These low end CAD tools absolutely need a grid system and most of the trace routing is done manually. The “Universal PCB
Design Grid System” impacts everything from CAD library creation, part
placement, via fanout to trace routing while at the same time consuming far
less computer memory and CPU processing. It also centers traces between pins
and vias increasing manufacturing yields. It also improves the overall
aesthetic look of the part placement and trace routing. The ultimate goal for IPC Standards and designing a perfect PCB is to have all element feature sizes in the PCB design rounded off in 0.05 mm increments and snapped to a 0.05mm grid system. Note: 0.05mm = 0.0019685” or almost 2 mils The Universal PCB
Design Grid System is based on the 0.05mm unit. All shapes and sizes for every
aspect of the PCB layout should be in increments of 0.05mm. Transitioning to
the metric system for PCB layout is necessary to achieve Electronic Product
Development Automation. The United States is
now the only industrialized country in the world that does not use the metric
system as its predominant system of measurement. However, PCB design worldwide
has been driven historically by the component manufacturers and CAD vendors to
use the Imperial measurement system. Clearly, U.S.
companies that do not produce products or services to metric specifications
will risk being increasingly noncompetitive in world markets. Japan has
identified the U.S. lack of metric usage as a strategic impediment to access of
U.S. products to the Japanese home market. In addition, consolidation of the
European market product standards will make sales of non-metric products
increasingly difficult and uncertain. Most U.S. companies understand that using
metric units is essential to future economic success. Their hesitation may be
due to uncertainty as to when and how to convert. Through their actions, U.S. federal agencies are demonstrating an increasing determination to use the metric system of units in business-related activities. Example: Most component manufacturers have converted their component dimensional datasheets to millimeter units. Many of the results are not yet very visible to the public, which is not a direct target of current federal transition activities. Most veterinary and medical institutions have completed the transition to metric units however, industry is the main target, and is becoming increasingly aware of and generally welcomes the government's progress. However, in the past 4 years USA government progress in the area for standards and metric conversion for the electronics industry has been dramatically reduced. And this is why PCB fabrication is stranded in the mil measurement system. There is no incentive for any USA manufacturer to transition and in an economy that's stagnant; no one has revenue for new equipment. As a matter of fact, over 2,000 PCB manufacturers have closed their operations in the USA and all of their machines and equipment went to auction for pennies on the dollar to existing manufacturer's. Industry acceptance of the wisdom of proceeding with the metric transition is due partly to the realization that producing to metric specifications and surviving in tomorrow's economic environment are synonymous. Most companies today export their products to a global market where metric based products are expected. It's interesting to note the component manufacturers, world standards organizations, assembly shops and many PCB designers have already transitioned to the metric unit system. When the PCB Fabrication companies in the USA transition to the metric unit system, then the global electronics industry will complete the full transition to a standard grid system. Micrometer units are definitely the future. I believe that 10 micrometers is better to express than 0.01 millimeters. It's the same thing as switching from Inches to Mils to remove the periods from the numbers. During the course of an average day, a PCB designer enters lots of numbers into a CAD tool and especially into the PCB Footprint Expert for PCB library creation. Typing in period's "." (or commas "," in Europe) slow progress down. Today, 80% of PCB desginers can get away with using a 0.05 mm grid system. However, due to the rise of micro-miniature component packages, by 2015 it will be common place for PCB designers to use a 10 micrometer grid system for everything from PCB library creation, part placement, trace routing and all PCB design features for pad sizes, trace widths, hole sizes, text heights, via sizes and board outlines.
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Posted By: adaptive
Date Posted: 05 Oct 2012 at 10:14am
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Tom,
I think I got it! I will create all of my footprints and drill holes in metric. The nature of our company is that unfortunately we will be always using mixed technology parts (.100" spacing on connectors, etc..) with our metric BGA's. However, I will convert all "imperial parts" to metric before saving it to library.
I guess I will have to trust our PCB fab shops to do the conversion from metric to imperial during the their fabrication proccess.
Thank you again,
Ed.
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Posted By: Mattylad
Date Posted: 05 Oct 2012 at 12:58pm
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I find that components always need to be created in mm, however for track/gap spacings, track widths etc thou is fine and there are no problems. Using mils (or thou as we use) is a much easier number to remember as I do not need to remember something point something, just something. And for schematics it does not matter a jot. It is however what the original symbol libraries used to create the symbols so adding metric pitch symbols in with imperial ones never works as they will not line up. At the end of the day its only a measurement unit and the user is free to use whichever unit they are most comfortable with to achieve their goal without making errors. Or in other words, using both is not a problem. |
Posted By: jameshead
Date Posted: 08 Oct 2012 at 12:26am
The nature of our company is that unfortunately we will be always using mixed technology parts (.100" spacing on connectors, etc..) with our metric BGA's. However, I will convert all "imperial parts" to metric before saving it to library. Using the 10 um or 0.01 mm grid then 0.1" being 2.54 mm means you don't have any problem here as long as you output your CAM data in the same units as your design and with one more degree of precision, i.e. mm 3.3. |
Posted By: adaptive
Date Posted: 09 Oct 2012 at 6:21am
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If I understand correctly, I should always create my footprints in metric. In case of a 2.54mm pin spacing (converted parts) I should use a routing grid of 0.01mm to match the pin spacing resolution. Finally, I need to generate my gerber files in metric units with 0.01mm resolution as well. Thank you for all of your feedback on my questions. |