{"id":953,"date":"2008-12-31T15:05:38","date_gmt":"2008-12-31T22:05:38","guid":{"rendered":"http:\/\/mightyohm.com\/blog\/?p=953"},"modified":"2015-09-26T11:11:10","modified_gmt":"2015-09-26T18:11:10","slug":"free-ipc-7351-land-pattern-calculator","status":"publish","type":"post","link":"https:\/\/mightyohm.com\/blog\/2008\/12\/free-ipc-7351-land-pattern-calculator\/","title":{"rendered":"Free IPC-7351 Land Pattern Calculator"},"content":{"rendered":"

Let’s say you are designing a printed circuit board in Eagle<\/a>, and you need to place a component that you’ve never used before.\u00a0 In Eagle, before you can use a new component, you need a land pattern, a schematic symbol, and a mapping between them to fully define the part.\u00a0 Often, you can search through Eagle’s included libraries and find what you need (or something close enough).\u00a0 But what if that fails?<\/p>\n

The symbol and pin definitions are usually pretty easy – just copy the datasheet.\u00a0 The hard part is the land pattern: the collection of copper traces, soldermask openings, silkscreen, and other features that define the part on the PCB.<\/p>\n

To come up with a land pattern, you usually have a few options:<\/p>\n

    \n
  1. Someone else may have done you a big favor by creating a part definition and uploading it to the Eagle library directory<\/a>.\u00a0 Caveat:<\/em> Use it at your own risk.\u00a0 Surface mount parts tend to be particularly hard to use right out of the box – often someone else’s land pattern won’t even pass your DRC.\u00a0 Whose process were they using, anyway??<\/em><\/li>\n
  2. Look through the datasheet for the part to try and find a recommended land pattern. (Good luck!\u00a0 Increasingly these are not included, but may be somewhere else on the manufacturer’s website.\u00a0 Google is your friend!)<\/li>\n
  3. Take a guess based on the geometry of the part, assuming you have a mechanical drawing or a physical sample somewhere.<\/li>\n
  4. Skip 1-3 and use an IPC-7351 land pattern generator.<\/li>\n<\/ol>\n

    IPC-7351 is a standard for printed circuit board land pattern designs.\u00a0 The standard attempts to, well, standardize land patterns to try to discourage every PCB designer from having his or her own custom library of land patterns.\u00a0 IPC takes known good land patterns and combines them with accepted manufacturing tolerances to produce a land pattern that will work for most people most of the time.\u00a0 Increasingly you will see references to IPC-7351 in datasheets instead of a land pattern drawing, so access to the standard is becoming more important over time.<\/p>\n

    Cool, right?\u00a0 Well, the bad news is that while you can browse through the table of contents\/introducton<\/a> for free, downloading the standard costs big bucks<\/a>.<\/p>\n

    Fortunately, PCB Matrix<\/a> has a free IPC-7351 Land Pattern Calculator<\/a> (direct download link here<\/a>) that you can use to generate land patterns based on the standard.\u00a0 You don’t need to own a copy of the standard to benefit from it.<\/p>\n

    The calculator is somewhat tricky to use but if you click the right buttons you can get something like what is shown below (click to enlarge).<\/p>\n

    \"Thin<\/a>
    PCB Matrix IPC-7351 Land Pattern Calculator Screenshot<\/figcaption><\/figure>\n

    X and Y are the dimensions of the recommended pads for an 8-lead Thin SOT-23, which happens to be the package for the LT3464<\/a>.<\/p>\n

    With this information, you can return to Eagle and create a land pattern for your device.\u00a0 PCB Matrix will also sell you premade Eagle libraries<\/a>, but from their site it was not clear how much they cost.\u00a0 Based on their other products, my guess is several hundred dollars and a yearly maintenance contract – I’ll draw my own, thanks.<\/p>\n

    Unfortunately, the calculator is Windows only, so Mac guys like me need to use VMware Fusion<\/a> or similar to use it.\u00a0 Can someone create a web version, please?<\/p>\n","protected":false},"excerpt":{"rendered":"

    Let’s say you are designing a printed circuit board in Eagle, and you need to place a component that you’ve never used before.\u00a0 In Eagle, before you can use a new component, you need a land pattern, a schematic symbol, and a mapping between them to fully define the part.\u00a0 Often, you can search through … Continue reading Free IPC-7351 Land Pattern Calculator<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[40,5,10],"tags":[98,32,133],"class_list":["post-953","post","type-post","status-publish","format-standard","hentry","category-books-and-resources","category-electronics","category-microcontrollers","tag-eagle","tag-pcb","tag-resources"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pioCd-fn","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"jetpack-related-posts":[{"id":979,"url":"https:\/\/mightyohm.com\/blog\/2009\/01\/gerbv\/","url_meta":{"origin":953,"position":0},"title":"gerbv – A free, open source gerber viewer for Linux \/ OS X","author":"Jeff","date":"January 5, 2009","format":false,"excerpt":"When you finish a PCB design, you typically use the CAM export function of your layout tool to generate a set of gerber files to send to the PCB manufacturer.\u00a0 To avoid errors in the finished board, it's usually a good idea to review the files before you click send.\u2026","rel":"","context":"In "Books and Resources"","block_context":{"text":"Books and Resources","link":"https:\/\/mightyohm.com\/blog\/category\/books-and-resources\/"},"img":{"alt_text":"gerbv screenshot","src":"https:\/\/i0.wp.com\/gerbv.sourceforge.net\/GerbvScreenshot.png?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":2318,"url":"https:\/\/mightyohm.com\/blog\/2009\/09\/svg-circuit-symbol-library\/","url_meta":{"origin":953,"position":1},"title":"SVG Circuit Symbol Library","author":"Jeff","date":"September 8, 2009","format":false,"excerpt":"Matthew Beckler has released a library of electronic component symbols in SVG format, which will make it easy for anyone with the vector drawing program Inkscape to create schematic diagrams quickly and easily.\u00a0 I have been meaning to learn Inkscape for the sole purpose of making prettier schematics, so this\u2026","rel":"","context":"In "Books and Resources"","block_context":{"text":"Books and Resources","link":"https:\/\/mightyohm.com\/blog\/category\/books-and-resources\/"},"img":{"alt_text":"SVG Circuit Symbols","src":"https:\/\/i0.wp.com\/www.mightyohm.com\/blog\/wp-content\/uploads\/2009\/09\/circuit_symbols.png?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":1103,"url":"https:\/\/mightyohm.com\/blog\/2009\/01\/poll-who-is-your-favorite-prototype-pcb-vendor\/","url_meta":{"origin":953,"position":2},"title":"Poll: Who is your favorite prototype PCB vendor?","author":"Jeff","date":"January 29, 2009","format":false,"excerpt":"As I wait for my AVR High Voltage Programmer Shield PCBs to come back from BatchPCB, I'm starting to wonder what prototype PCB services other people are using for their boards. Ladyada has a PCB Cost Comparison Calculator that shows the significant differences in price between various low volume PCB\u2026","rel":"","context":"In "Books and Resources"","block_context":{"text":"Books and Resources","link":"https:\/\/mightyohm.com\/blog\/category\/books-and-resources\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1639,"url":"https:\/\/mightyohm.com\/blog\/2009\/04\/esc-beagle-board-class-wrapup\/","url_meta":{"origin":953,"position":3},"title":"ESC Beagle Board Class Wrapup","author":"Jeff","date":"April 2, 2009","format":false,"excerpt":"This week I attended the Build Your Own Embedded System (BYOES) classes at ESC 2009. The BYOES classes were primarily focused on the Beagle Board, an ARM Cortex-A8 based single board computer developed by engineers at Texas Instruments. When I picked up my conference registration on-site, I also received a\u2026","rel":"","context":"In "Events"","block_context":{"text":"Events","link":"https:\/\/mightyohm.com\/blog\/category\/events\/"},"img":{"alt_text":"Rev C2 Beagle Board","src":"https:\/\/i0.wp.com\/mightyohm.com\/files\/flickr\/3403824732_a60042ed71.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":968,"url":"https:\/\/mightyohm.com\/blog\/2009\/01\/avr-hv-programmer-shield-in-the-works\/","url_meta":{"origin":953,"position":4},"title":"AVR HV Programmer Shield in the Works!","author":"Jeff","date":"January 2, 2009","format":false,"excerpt":"What's this??? In response to the continued demand for a PCB version of my Arduino-based AVR High Voltage Programmer, I just released a first cut to BatchPCB and should have a prototype within 3-4 weeks. This design is an improvement upon the original HV programmer shield in the following areas:\u2026","rel":"","context":"In "Microcontrollers"","block_context":{"text":"Microcontrollers","link":"https:\/\/mightyohm.com\/blog\/category\/microcontrollers\/"},"img":{"alt_text":"hvfuse_shield3_brd","src":"https:\/\/i0.wp.com\/mightyohm.com\/blog\/wp-content\/uploads\/2009\/01\/hvfuse_shield3_brd-424x500.png?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":3190,"url":"https:\/\/mightyohm.com\/blog\/2010\/10\/diy-integrated-circuit-design-with-mosis\/","url_meta":{"origin":953,"position":5},"title":"DIY Integrated Circuit Design with MOSIS","author":"Jeff","date":"October 25, 2010","format":false,"excerpt":"MOSIS, short for Metal Oxide Semiconductor Implementation Service,\u00a0is to integrated circuits what BatchPCB is to printed circuit boards. \u00a0That is, it's a batch order service that makes getting your own custom ICs fabricated more affordable by allowing lots of designers to contribute their designs and share the costs of a\u2026","rel":"","context":"In "Electronics"","block_context":{"text":"Electronics","link":"https:\/\/mightyohm.com\/blog\/category\/electronics\/"},"img":{"alt_text":"Photo: SATRE ELECTRONICS","src":"https:\/\/i0.wp.com\/mightyohm.com\/blog\/wp-content\/uploads\/2010\/10\/EC101_Layout_50-500x363.jpg?resize=350%2C200","width":350,"height":200},"classes":[]}],"_links":{"self":[{"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/posts\/953","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/comments?post=953"}],"version-history":[{"count":9,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/posts\/953\/revisions"}],"predecessor-version":[{"id":7907,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/posts\/953\/revisions\/7907"}],"wp:attachment":[{"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/media?parent=953"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/categories?post=953"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/tags?post=953"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}