Paul,

Maybe. Depends on the amount of temperature variation and the consequent 
change in stiffness of the board and how expensive a finite element 
package I had. Note Tan didn't say he interested in behaviour at reflow 
temperatures.

Loss tangent may be more important if Tan is interested in amplitude ratios.

Regards,



Paul Reid wrote:
> Hi Eric,
>
> In your FEM would you include changes in Young's modulus of the FR4 with each thermal excursion to 260°C?
>
> Regards,
>
> Paul 
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Eric CHRISTISON
> Sent: Thursday, August 14, 2008 8:04 AM
> To: [log in to unmask]
> Subject: Re: [TN] Elasticity
>
> Tan,
>
> By building a finite element model of the assembly you are interested in and then carrying out the appropriate analysis on the model you can determine displacements, deflections and stresses in the assembly.
>
> After that you can make an assessment of whether or not the assembly is going to survive. Of course the assessment is the hard bit...
>
> Regards,
>
>
>
> Tan Geok Ang wrote:
>   
>> We are evaluating different axis's and levels of G-vibration test with different temperatures.  
>> Not CTE...
>> What is E-module?
>>
>> ________________________________
>>
>> From: Hernefjord Ingemar [mailto:[log in to unmask]]
>> Sent: Thu 8/14/2008 4:07 PM
>> To: TechNet E-Mail Forum; Tan Geok Ang
>> Subject: RE: Elasticity
>>
>>
>>
>> you mean CTE ?  Or E-module ? Why do you ask and what's the issue?
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Tan Geok Ang
>> Sent: den 14 augusti 2008 03:11
>> To: [log in to unmask]
>> Subject: [TN] Elasticity
>>
>> Hi All,
>>                 Can the elasticity of FR4 rigid PCB and solder joints (SnPb, SAC) be definite (with value)? Thanks in advance.
>>
>> Best Regards
>> GA Tan
>>
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>
> --
> Eric Christison Msc
> Mechanical Engineer
> Consumer & Micro group
> Imaging Division
>
> STMicroelectronics (R&D) Ltd
> 33 Pinkhill
> Edinburgh EH12 7BF
> United Kingdom
>
> Tel:	+44 (0)131 336 6165
> Fax:	+ 44 (0)131 336 6001
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
> -----------------------------------------------------
>
>   

-- 
Eric Christison Msc
Mechanical Engineer
Consumer & Micro group
Imaging Division

STMicroelectronics (R&D) Ltd
33 Pinkhill
Edinburgh EH12 7BF
United Kingdom

Tel:	+44 (0)131 336 6165
Fax:	+ 44 (0)131 336 6001

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