Ian,
Good question! In a word, no. Why? No need. Lead solved the problem.
It would be highly one could get IR&D or government funding for research on why tin grows whiskers.
An interesting phenomenon but there are lots of more important phenomena that need studying, are there not?
That is until the EU decided to ban lead from eutectic tin solder and compounded the problem by not waiting until suffient data was in that the new solders (and platings) did not grow whiskers under ANY conditions or that if they did they were miniscule and of no consequence.
Of course, at the same time the EU banned lead in solder, the geometries of parts had shrunk enormously since the 1950's, 1960's and 1970's when the studies were done.
A perfect environment was created to grow whiskers and introduce all kinds of metalurgical unknowns as all these new solders are just that, NEW with very little real life long term experience.
Now we get to go through the same learning curve again.
And that took how long?
And meanwhile we want to make profits and we want our products to be trouble free (and, oh yes, not kill anyone)?
Bob Landman
H&L Instruments, LLC
-----Original Message-----
From: Ian Hanna [mailto:[log in to unmask]]
Sent: Thursday, February 18, 2010 4:08 PM
To: Bob Landman; [log in to unmask]
Subject: RE: [TN] Pace maker recall URL
have a look at the REFERENCES:
1. "Eliminate Whisker Growth on Contacts by Using a Tin Alloy
Plate," R.P. Diehl & N.A. Cifaldi, Insulation/Circuits, pp. 37-39, Apr.
1976.
2. "How to Avoid Metallic Growth Problems on Electronic Hardware,"
Tech Report IPC-TR-476, The Institute for Interconnecting & Packaging Electronic Circuits (IPC), 1977.
3. "Identification of Fused Tin Coatings on Integrated Circuit
Device Leads," W.G. Bader, Plating & Surface Finishing, pp. 56-57, Aug.
1977.
4. "Spontaneous Growth of Whiskers on Tin Coatings: 20 Years of
Observation," S.C. Britton, Trans. Inst. of Metal Finishing, Vol 52, pp.
95-102, Apr. 1974.
5. "Tin Whiskers: Causes & Remedies," N.A.J. Sabbagh & H.J.
McQueen, Metal Finishing, pp. 27-31, Mar. 1975.
has anybody done anything relevent since 1977?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Landman
Sent: Thursday, February 18, 2010 2:43 PM
To: [log in to unmask]
Subject: Re: [TN] Pace maker recall URL
Actually, we don't know what caused the "separation of wires". Where did the wires separate and why? A connector problem? A solder problem?
The FDA document is useless.
This is interesting http://www.yourlawyer.com/articles/read/16568
"Medtronic said it has received reports of two patient deaths where it is possible, but unclear, whether a wire separation issue may have been a factor."
The Medtronic document is actually more revealing http://www.medtronic.com/crm/performance/advisories/sigma-nov2005.html
Sigma Implantable Pulse Generators
Original Date of Advisory: November 2005 Potential Separation of Interconnect Wires Product
A specific subset of Sigma series pacemakers may fail due to separation of interconnect wires from the hybrid circuit. Specific model and serial numbers of affected devices are available online at:http://SigmaSNList.medtronic.com.
Advisory
This subset of Sigma series pacemakers that may fail due to separation of interconnect wires from the hybrid circuit may present clinically as loss of rate response, premature battery depletion, intermittent or total loss of telemetry, or no output.
Separation of redundant interconnect wires has been observed on hybrid terminal blocks. Device failure occurs only where both interconnect wires separate from a hybrid terminal block. In October 2005, testing and analysis identified the root cause of these failures and the affected population. Hybrid circuits used in this subset of devices were cleaned during manufacturing with a particular cleaning solvent that could potentially reduce the strength of the interconnect wire bond over time.
No provocative testing can predict which devices may fail.
Patient Management Recommendations
Recommendation for the management of patients who have pacemakers affected by this advisory were changed in May 2009. Current recommendations are:
We realize that each patient requires unique clinical consideration and we support your judgment in caring for your patients. After consultation with Medtronic's Independent Physician Quality Panel, Medtronic offers the following recommendations for patients in the 2005 Sigma advisory:
* Physicians should advise their patients to seek medical attention immediately if they experience symptoms (e.g., fainting or lightheadedness).
* Physicians should consider device replacement for patients who are both pacemaker dependent and who have been implanted with a device in the affected subsets. Medtronic will offer a supplemental device warranty if the device is not already at elective replacement time.
* Physicians should continue routine follow-up in accordance with standard practice for those patients who are not pacemaker dependent.
Status Update
As of July 31, 2009, 328 devices out of approximately 40,000 devices worldwide have been confirmed as having experienced interconnect wire separation. Seventy-five (75) of these devices were returned from the United States.
One hundred ninety-three (193) of the 328 devices (0.46%) were returned with information indicating a problem with the patient's pacing system prior to explant. The remaining 135 devices (0.32%) were returned with no information indicating a potential malfunction while implanted or with insufficient information to determine the state of the device at explant. Lacking definite information indicating proper operation until explant, these devices are conservatively categorized as having experienced interconnect wire separation while implanted.
Our original modeling predicted a failure rate from 0.17% to 0.30% over the remaining lifetime of these pacemakers. However, updated modeling now predicts a failure rate of 3.9% over the remaining device life.
Out of the initial advisory population of 40,000 worldwide, approximately 13,100 remain implanted. Approximately 3,100 of these are in the United States.
=====================
Bob Landman
H&L Instruments, LLC
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Reliability Resources
Sent: Thursday, February 18, 2010 12:00 PM
To: [log in to unmask]
Subject: Re: [TN] Pace maker recall URL
This recall was not caused by tin whiskers.
http://www.fda.gov/MedicalDevices/Safety/RecallsCorrectionsRemovals/List
ofRe
calls/ucm166344.htm
Reason for Recall: The Kappa and Sigma pacemakers in these identified series may fail due to a separation of wires that connect the electronic circuit to other pacemaker components, such as the battery.
Clayton Bonn
Reliability Resources
Ph: 714-612-9359
e-mail:[log in to unmask]
www.reliability-resources.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ahne Oosterhof
Sent: Wednesday, February 17, 2010 1:47 PM
To: [log in to unmask]
Subject: Re: [TN] Pace maker recall URL
I like this sentence in that FDA announcement under conclusions:
Untreated tin coating should never be used in conjunction with electronic circuitry.
Especially the generalization of the statement!
That page was last updated 30Apr09.
Ahne.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brooks, Bill
Sent: Wednesday, February 17, 2010 12:42
To: [log in to unmask]
Subject: Re: [TN] Pace maker recall URL
http://www.fda.gov/ICECI/Inspections/InspectionGuides/InspectionTechnica
lGuides/ucm072921.htm
Check that link out...
Bill Brooks | Datron World Communications, Inc.
PCB Designer/Engineer | Office: 760-602-7004| Fax: 760-597-3777 | [log in to unmask] 1808 Aston Avenue, Suite 230, Carlsbad, CA 92008 | www.dtwc.com
Performance You Require. Value You ExpectTM
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Roberts, Jon (SA-1)
Sent: Wednesday, February 17, 2010 12:17 PM
To: [log in to unmask]
Subject: Re: [TN] Pace maker recall URL
I did not readily see the root cause on any of the Medtronic recalls. So where is the actual report stated it was whiskers? I may have missed it, Thanks, Jon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Burke
Sent: Wednesday, February 17, 2010 1:37 PM
To: [log in to unmask]
Subject: Re: [TN] Pace maker recall URL
Here you go:
6) FDA forced Medtronic to recall their implanted cardiac defibrilators (from patients bodies) when whiskers shorted the devices.
http://www.fda.gov/ora/inspect_ref/itg/itg42.html
John Burke
(408) 515 4992
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
Sent: Wednesday, February 17, 2010 9:19 AM
To: [log in to unmask]
Subject: [TN] Pace maker recall URL
Fellow TechNetters:
A few weeks back on of the subscriber share health information about a
recall pace maker which I found very interesting. How, I am not able
to
locate that link now that I have a need for it. That subscriber share that URL site once again.
In advance I thank you for your timely response in this matter.
Victor,
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