Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes Calculators Education Engineering Magazine Articles Engineering software RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising RF Cafe Forums Magazine Sponsor RF Cafe RF Electronics Symbols for Visio RF Electronics Symbols for Office Word RF Electronics Stencils for Visio Sponsor Links Saturday Evening Post NEETS EW Radar Handbook Microwave Museum About RF Cafe Aegis Power Systems Anritsu Alliance Test Equipment Amplifier Solutions Anatech Electronics Axiom Test Equipment Berkeley Nucleonics Bittele Centric RF Conduct RF Copper Mountain Technologies Empower RF everything RF Exodus Advanced Communications Innovative Power Products ISOTEC KR Filters Lotus Systems PCB Directory Rigol RF Superstore San Francisco Circuits Reactel RFCT TotalTemp Technologies Triad RF Systems Windfreak Technologies Withwave LadyBug Technologies Wireless Telecom Group Sponsorship Rates RF Cafe Software Resources Vintage Magazines Thank you for visiting RF Cafe!
Copper Mountain Technologies (VNA) - RF Cafe

ESD - RF Cafe Forums

RF Cafe Forums closed its virtual doors in 2010 mainly due to other social media platforms dominating public commenting venues. RF Cafe Forums began sometime around August of 2003 and was quite well-attended for many years. By 2010, Facebook and Twitter were overwhelmingly dominating online personal interaction, and RF Cafe Forums activity dropped off precipitously. Regardless, there are still lots of great posts in the archive that ware worth looking at. Below are the old forum threads, including responses to the original posts.

NOTICE: The original RF Cafe Forum is available again for reading, and the new RF Cafe Blog is an active board.

-- Amateur Radio

-- Anecdotes, Gripes, & Humor

-- Antennas

-- CAE, CAD, & Software

-- Circuits & Components

-- Employment & Interviews

-- Miscellany

-- Swap Shop

-- Systems

-- Test & Measurement

-- Webmaster

smanoha

Post subject: ESD Posted: Thu Aug 31, 2006 4:44 am

Captain

Joined: Tue Apr 25, 2006 2:01 am

Posts: 7

An on-chip integrated TTL driver that we designed for a six bit phase shifter appears prone to ESD issues. After on-wafer testing or after assembly operations, certain bits in a previously working phase shifter fail to turn on. Inspection under a microscope usually reveals a burnt out device or fused transmission lines (at places where one metal layer crosses over another, the separating dielectric is 0.15 microns thick with a dielectric constant of 6.65) in the driver. As I stated earlier, we suspect ESD; we have been careful to take the necessary precautions such as wearing anti-static clothing and wrist straps when handling the chips but the problems persist. I was wondering if there might be other potential reliability issues that I was'nt aware off. I would also like to hear from you on ESD protection circuitry that we could incorporate off-chip.

Top

nubbage

Post subject: ESDPosted: Thu Aug 31, 2006 7:14 am

General

Joined: Fri Feb 17, 2006 12:07 pm

Posts: 218

Location: London UK

I have read over the last year in the electronic press a lot of reports of chip and circuit failures due to decreasing use of, or even elimination of, lead for soldering, and an increased use of tin.

You might encounter solution of one metal into another that eventually "corrodes" one track away.

Another problem is, with increasing presence of tin, there is a crystalline growth in metallic tin that can track across from one conductor to another. It is called "tin tree". Check it out.

The intrinsic impedance of TTL is usually considered so low that one can forget about ESD effects under normal lab or assembly shop conditions.

Top

smanoha

Post subject: Re:ESDPosted: Thu Aug 31, 2006 7:57 am

Captain

Joined: Tue Apr 25, 2006 2:01 am

Posts: 7

Thanks Nubbage for your reply. By 'TTL driver' I actually meant to say that our on-chip driver accepts a TTL input (0V/5V) and converts it to the voltage levels (-2.5V/+0.5V) needed to switch the pHEMTs in the phase shifter. The driver was designed using 0.5 micron gate length pHEMTs and schottky diodes.

Top

nubbage

Post subject: ESDPosted: Thu Aug 31, 2006 9:31 am

General

Joined: Fri Feb 17, 2006 12:07 pm

Posts: 218

Location: London UK

Aha

I had a lot of trouble with punch-through failure of Schottky diodes in the presence of fast ie short rise-time pulses in a radar system with PIN switches followed by Schottky diode detectors (Agilent 2800 types). We ultimately traced the problem to the presence of high current narrow pulse circulation on the ground-planes. The diodes were lasting about 30 minutes to 2 hours, then failing due to puch-through.

The product never made it through the next phase of re-design, as the division closed shortly afterwards.

The only experience I can offer is that Schottky technology is not as robust as the manufacturers would like us to believe, especially when diodes are in the presence of transient pulses, or I guess static discharge, which is a similar phenomenon.

Top

Stephen

Post subject: Posted: Sat Sep 02, 2006 12:41 am

Captain

Joined: Wed Jun 21, 2006 8:33 pm

Posts: 21

Location: Queen Creek, Arizona

Smanoha,

Your first question is correct, can you verify that this is a true ESD issue.

My question for you is this:

When you find the metal track fusing, do you also find a burned out device?

From your comments, it appears the metal track fusing is the more common failure. But this is important as there are very few cases of ESD failure due to metal only, metal failures as a result of ESD/EOS related issues are almost always accompanied first by device burn-out/failures that then conduct so much current at such high power densities that we see metal failures.

Metal track and ILD breakdowns are almost always the strongest link in the ESD currrent path, and the last parts to fail, assuming proper diligence was designed into the ESD architecture (obviously esd currents can not be expected to flow through a 1 um wide signal bus).

Now, if you have device burnout, and it is located directly under or near your melting metal tracks, or especially if it is part of the ESD current paths, then this could likely be a result of ESD/EOS events as the secondary effects of temperature and high currents passing through or nearby your node could create this problem. But I again stress that it is very unlikely that this track is your primary ESD failure.

If you are seeing only this track shorting, unaccompanied by failed devices, the corrosion theory suggested by Nubbage would be a more likely candidate, or maybe an electromigration issue. Another issue could be antenna effects from processing and early testing, if the tracks failing are high impedance nodes with no leakage paths. (essentially an EOS failure).

I am going to end this, as further comments are even more prone to speculation at this point, but to better answer your question of wether it is ESD, more info must be shared regarding the types of failure you are seeing, and what are the relationships of failing nodes to bond pads and ESD current paths. (are the tracks part of the IO, power busses, or internal signals with no direct relationship or connectivty to bond pads, etc).

I hope this helps,

Stephen

_________________

CMOS RF and Analog ESD Specialist!

www.srftechnologies.com

Posted  11/12/2012

RF Electronics Shapes, Stencils for Office, Visio by RF Cafe
Innovative Power Products Passive RF Products - RF Cafe
PCB Directory (Manufacturers)
Lotus Communication Systems Modular RF Component Building Blocks - RF Cafe
Windfreak Technologies Frequency Synthesizers - RF Cafe

Please Support RF Cafe by purchasing my  ridiculously low−priced products, all of which I created.

These Are Available for Free

 

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024

Webmaster:

    Kirt Blattenberger,

    BSEE - KB3UON

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website:

AirplanesAndRockets.com