Teardrop (electronics)
Ateardropis typically drop-shaped feature on aprinted circuit boardand can be found on the junction ofviasorcontact pads.
Purpose
[edit]The main purpose of teardrops is to enhancestructural integrityin presence of thermal ormechanical stresses,[1][2][3]for example due to vibration or flexing.[4]Structural integrity may be compromised, e.g., by misalignment during drilling, so that too muchcoppermay be removed by the drill hole in the area where a trace connects to the pad or via.[2][3][5]An extra advantage is the enlarging of manufacturing tolerances, making manufacturing easier and cheaper.[3]
Shape
[edit]While a typical shape of a teardrop is straight-line tapering, they may be concave.[2]This type of teardrop is also calledfilletingorstraight.[3]To produce asnowman-shaped teardrop, a secondary pad of smaller size is added at the junction overlapping with the primary pad (hence the nickname).[3][6]
Necking
[edit]For similar reasons, a technique calledtrace neckingreduces (ornecks down[7][8][9]) the width of a trace that approaches a narrower pad of asurface-mounted deviceor athrough-holewith a diameter that is less than the width of the trace, or when the trace passes through bottlenecks (for example, between the pads of a component).[8][9][10][11]
References
[edit]- ^Wahby, Mahmoud (2014-02-21)."Component placement tips and strategies".EDN Network.Archivedfrom the original on 2017-09-24.Retrieved2017-09-24.
- ^abcLoughhead, Phil (2017-05-30)."Removing Unused Pads and Adding Teardrops".Altium Designertechnical documentation.Altium.Archivedfrom the original on 2017-09-24.Retrieved2017-09-24.
- ^abcdeKolath, Amos (2010)."Why Where When and how teardrops should be added to PCB?".KaiZen Technologies.Archivedfrom the original on 2017-09-24.Retrieved2017-09-24.
- ^Ruth (2023-04-28)."Introduction to high speed PCB and is it same as high frequency PCB".IBE Electronics.Retrieved2023-05-01.
- ^Lobner, Wilhelm (October 2002)."Empfehlung zu Tear-drops"[Recommendations for tear-drops](PDF)(in German). AT&S AG.Archived(PDF)from the original on 2017-09-24.Retrieved2017-09-24.
- ^Gutierrez, Keith G.; Coates, Keven (June 2010)."PCB Design Guidelines for 0.5mm Package-on-Package Applications Processor, Part I"(PDF).Texas Instruments. Application Report SPRABB3.Archived(PDF)from the original on 2017-09-24.Retrieved2015-07-27.
- ^Loughhead, Phil (2017-04-25)."Interactive Routing".Altium Designertechnical documentation.Altium.Archivedfrom the original on 2017-09-24.Retrieved2017-09-24.
- ^abByers, T. J. (1991-08-01).Printed Circuit Board Design with Microcomputers(1 ed.). McGraw-Hill Book Company. p. 102.ISBN0070095582.LCCN91-72187.
- ^abKollipara, Ravindranath; Tripathi, Vijai K.; Sergent, Jerry E.; Blackwell, Glenn R.; White, Donald; Staszak, Zbigniew J. (2005)."11.1.3 Packaging Electronic Systems - Design of Printed Wiring Boards"(PDF).In Whitaker, Jerry C.; Dorf, Richard C. (eds.).The Electronics Handbook(2 ed.). CRC Press. p. 1266.ISBN978-0-8493-1889-4.LCCN2004057106.Archived(PDF)from the original on 2017-09-25.Retrieved2017-09-25.
- ^US 3560256,Abrams, Halle, "Packaging Electronic Systems", published 1971-02-02, assigned toWestern Electric Co.
- ^Thierauf, Stephen C. (2004).High-Speed Circuit Board Signal Integrity(1 ed.). Artech House, Inc. pp. 104–105.ISBN1580531318.
External links
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