[SI-LIST] Re: Inserion loss of fr4 , 50 ohm trace .

  • From: steve weir <weirsi@xxxxxxxxxx>
  • To: si-list@xxxxxxxxxxxxx
  • Date: Wed, 27 Nov 2013 10:17:32 -0800

Have you built any test structures into your boards?  Are you seeing 
similar loss with the on board transmitter as with a VNA?  Have you 
measured before and after scraping away the solder mask?

Steve
On 11/27/2013 9:53 AM, sunil bharadwaz wrote:
> Thanks to all who have replied & contributed to this thread so far ..
> I have done little more investigation with the fab . From what i seem to 
> gather is that ,
> the ENIG coat is only done at the Component foot print pads . Meaning , if 
> there is a long
> RF trace , ENIG would be coated at the start point , where RF IC is soldered 
> .The O/P
> trace of the RF IC to the Antenna ( long trace , where unexpected insertion 
> loss )  ,
> would not have the ENIG coated . So nickel coat may not be the reason .
> Is my thinking right or am i missing anything fundamentally ?
>
> Regards
> Sunil.B
>
>
>
>
> On Sunday, November 24, 2013 9:57 PM, steve weir <weirsi@xxxxxxxxxx> wrote:
>   
> Hassan, I don't know what is happening to your messages, but you might
> try removing the SI-List tags at the bottom of your mail.  I found that
> the parser sometimes get confuses them for commands.
> Steve.
> On 11/24/2013 8:18 AM, Hassan O. Ali wrote:
>> cccc cc
>> cccc cc
>> cccc cc
>>
>> Sorry, my messages get strangely truncated.
>>
>> Steve, suppression of resonance is a good point but that's not what I
>> meant. I think the wide (18mil) CPW gap will lead to more fringing
>> field in air than in microstrip case. That wouldn't be the case if the
>> gap were small.
>>
>> Hope this doesn't get truncated.
>>
>> Best regards,
>>
>> Hassan.
>>
>>


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