I'm not an expert on this stuff but in case one doesn't turn up to answer:
Rex Waygood wrote:
> And another
> Given that peel strength is often quoted before and after high temp exposure and processing, which indicates to me that the copper to substrate interface is not stable, how do the FE guys model that interface?
If you're thinking about plastic deformation in the interface then you'd
have to use some sort of non linear analysis.
> It has always seemed to me that relaxation will occur at that interface during TC dwell and some compliance will come from that interface. Does it matter which way the tracks depart from the pads?
>
Almost certainly.
If you're interested in the assmbly's behaviour after reflow then the
issue is one of characterisation of the different mechanical properties
and the application of failure criteria based on those properties.
> Just curious...............
>
>
> Rex Waygood
> Technical Manager
>
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> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Paul Reid
> Sent: 14 August 2008 13:20
> To: [log in to unmask]
> Subject: Re: [TN] Elasticity
>
> 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
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--
Eric Christison Msc
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Consumer & Micro group
Imaging Division
STMicroelectronics (R&D) Ltd
33 Pinkhill
Edinburgh EH12 7BF
United Kingdom
Tel: +44 (0)131 336 6165
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