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Why 50 mils in 0805 package instead of 40 mils.

#25934

Why 50 mils in 0805 package instead of 40 mils. | 3 October, 2003

All the packages like 0603,0402,0201 have half the width as compared to length but in case of 0805 package width is 50 mils instead of 40 mils. Is there any special reason designing point of view. Please tell if anybody knows.

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#25940

Why 50 mils in 0805 package instead of 40 mils. | 3 October, 2003

EIA standard packages have a variety of L/W proportions.

EIA||Dimension mm (LXW)||Proportion (L/W) 0201||0.6X0.3||2 0202||0.5X0.5||1 0303||0.8X0.8||1 0402||1.0X0.5||2 0504||1.25X1.0||1.25 ||1.4X1.4||1 0603||1.6X0.8||2 0805||2.0X1.25||1.6 1111||2.8X2.8||1 1206||3.2X1.6||2 1210||3.2X2.5||1.28 1808||4.5X2.0||1.25 1812||4.5X3.2||1.41 2211||5.7X2.8||2.04 2220||5.7X5.0||1.14

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iman

#25957

Why 50 mils in 0805 package instead of 40 mils. | 6 October, 2003

Does the EIA standard recommend any standard PCB pad sizes (LxB)? and pitch-to-pitch (Pad) distances? Thanks for the advise.

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#25958

Why 50 mils in 0805 package instead of 40 mils. | 6 October, 2003

The EIA does not provide that information. EIA standards focus on component dimensions. Alternately consider:

...cut... SM-782A - Surface Mount Design & Land Pattern Standard, Inc. Am. 1 & 2

ANSI Approved

Get up-to-date land pattern recommendations for ball grid array packages with this latest printing of the popular IPC-SM-782A standard. The document covers land patterns for all types of passive and active components, including resistors, capacitors, MELFs, SOTs, SOPs, SOICs, TSOPs, QFPs, LCCS, PLCCS, and most recently, BGAs. Also included are EIA/JEDEC registered components, land pattern guidelines for wave or reflow soldering, a sophisticated dimensioning system, via location guidelines and V-groove scoring. Includes Amendments 1 and 2. 222 pages. Released January 2000. ...cut...

As an alternative, consider patterns developed by Jim Blankenhorn [ http://www.smtplus.com ]. Jim is a SMTnet.com supporter; knowledgeable educator, writer, and consultant on electronic manufacturing; and publisher of SMT information. His patterns are well accepted and distinguish themselves from the IPC patterns by recognizing the need for alternate patterns for different part densities.

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iman

#25979

Why 50 mils in 0805 package instead of 40 mils. | 6 October, 2003

Yo! thanks! for the link, too bad it costs USD$1K+ for single site license fee.

IPC's specs are great for customer level discussions, but its guys like 'smtplus' who help get the warzone DFM into action, coz its guys like us who need to do the ground work and could do with all the help we can get.

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#25986

Why 50 mils in 0805 package instead of 40 mils. | 7 October, 2003

If don't want to be distracted by those things, why not just use the pattern calculator on the IPC site?

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MA/NY DDave

#26014

Why 50 mils in 0805 package instead of 40 mils. | 10 October, 2003

Hi SMTAnet, SMTnet,

You already got good answers for how to go forward.

I believe that this 50mils is a remnant of the days when we started at 125 mil grids and started the process of going down to 100mil grids, SMT. My gosh who would ever want a 100 mil grid product or SMT, it is so so difficult. It is part of the lore and the difficulty in on-grid, off-grid CAD design of the old grid days is my belief.

YiEngr, MA/NY DDave

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