Electronics Forum: corners (Page 13 of 66)

Polarity for SMT Devices

Electronics Forum | Tue May 28 08:31:49 EDT 2002 | Hussman69

Hello, I know I will probably get a dozen "check the archives" answers, but what the heck. What is YOUR typical polarity mark for SMT devices? Do you use silk screen or cut a corner off a pad? Let me know and thanks.

BGA Assembly

Electronics Forum | Wed May 29 10:52:56 EDT 2002 | slthomas

Just wondering why you'd use a diamond shaped aperture? Seems like it'll just fill in the corners and be pretty much round anyway, so why not just start out that way and keep the volume you want?

UltraSonic cleaning machine

Electronics Forum | Wed Sep 25 10:13:32 EDT 2002 | davef

I don't think 'this a blatant violation of rules' as such. I think it is a blantant disrespect of the principle of free and open communication that is the corner stone of interenet forums and a slap in the face of everyone that wants to learn more a

Fine pitch paste release problems.

Electronics Forum | Thu Dec 19 13:25:19 EST 2002 | russ

We actually look at it like this, The area of a circle that will fit into a square is less. (slight overprint with square aperture with radiused corners) Russ

0402 stencil design

Electronics Forum | Wed Feb 05 21:24:35 EST 2003 | davef

Stephen's correct. Radiased outer corners on 0402 pads really do seem to improve things. We aim to try "squared-up semicircles".

BGA Bowing on the corners.

Electronics Forum | Sat Aug 23 08:26:54 EDT 2003 | davef

In line with Russ' comment, look here: http://www.smtnet.com/forums/Index.cfm?CFApp=1&Message_ID=22497

BGA Bowing on the corners.

Electronics Forum | Mon Aug 25 20:29:02 EDT 2003 | davef

For further discussion on the "being hosed by the physics": http://www.cooksonsemi.com/tech_art/pdfs/Controlling%20Warpage.pdf

QFP Coplanarity & Alloy 42

Electronics Forum | Wed Oct 01 15:06:50 EDT 2003 | davef

You're thinking correctly. Concentrate your recipe development efforts by profiling directly on the pads [that some fine designer forgot to thermally isolate properly] of those pesky corner leads that don't solder well.

QFP soldering issue

Electronics Forum | Mon Jan 12 08:59:57 EST 2004 | Paul F

I may have a similar problem at the moment with a QFP-68. Do the unsoldered leads leave a perfectly formed footprint in the reflowed solder? Do you usually find this issue occurring towards the corners of the QFP rather than in the middle of a row?

BGA and QFP orientation in trays for pick and place

Electronics Forum | Thu Jan 15 12:55:03 EST 2004 | James

Polarity in tape and reel is usually always on the bottom left side. And that is correct for the trays, they have a corner taken out where the polarity goes. Hope that helps........


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