[SI-LIST] R: Re: R: Re: Wire bonding

  • From: <gianguida@xxxxxxxx>
  • To: "Douglas Burns" <dburns@xxxxxxxxxx>, <weirsi@xxxxxxxxxx>, "Xilei Liu" <xileil@xxxxxxxxxxx>, <steven.salkow@xxxxxxxx>, <si-list@xxxxxxxxxxxxx>
  • Date: Wed, 9 Aug 2006 15:55:41 +0200

Hi Douglas,
possibly I wrongly used the words easy..
what I want to say is that to create a model to simulate the effects of some 
wirebonds 
cannot take several days just to setup the model...
About the possibility to use FIELD SOLVER for complex package...

both Ansoft and CST has specialized tool able to read the layout directly from 
the layout package tool 
and able to
create model for HFSS and MWS where it is necessary only to setup the port.
I have seen very accurate results in the analysis of 
complex part of the package done with both tools.
to not talk about tool specialized in the packa ge analysis.

You absolutely right when you say that it is always necessary to 
be careful using simulation tool...
but this is even more true with measurement...isn't it?

A wrong measurement it isn't better than a wrong simulation...:-)))

At the end of the day you right when you say

"You really have to understand what the expected results should be (by hand
calculation, simple 2-D model, etc) when building a complex model and then
test the model (DC, Frequency domain, Transient) to ensure that a good model
has been built"
but this is "just" what a good engineer should do everytime.

Giancarlo

-----Messaggio originale-----
Da: Douglas Burns [mailto:dburns@xxxxxxxxxx]
Inviato: mer 09/08/2006 15.02
A: weirsi@xxxxxxxxxx; 'Xilei Liu'; gianguida@xxxxxxxx; steven.salkow@xxxxxxxx; 
si-list@xxxxxxxxxxxxx
Oggetto: RE: [SI-LIST] Re: R: Re: Wire bonding
 
The real difficulty with accurate modeling of wirebonds lie in the various
bonding arcs and bond wire lengths that occur in a design. 

1) If you assume all signals bond from the chip to a set of bond fingers,
you must include in the model only the length variations due to bond angle.
You assume that the height of the bond arc is identical for all wires (not
actually true, but almost impossible to model)

2) If you have a package that contains power rings, now the model needs to
not only represent a region of the package, but the model has to account for
different bond angles, different bond heights, and various bond lengths.
This can make building the model time-consuming. 


In terms of the comment that 3-D modeling is easy, I'd have to say that it
really depends on what is being modeled. If we are talking about a simple 4
layer package with routing on the top, 2 power layers, and a ball layer,
sure building a model in fairly straight forward (ignoring issues with
wirebonds). On the other hand, if you start playing with a multi-layer
package with routing on multiple layers, extracting a good model is not
measured in hours. Sure you can read the database in quickly, but setting
ports, extracting, validating that the model is correct all take time.
 
The biggest problem with 3-D tools is that it is easy to set things up
incorrectly (ports, mesh, etc), yet the tool will solve and provide a model.
If you just use the model because the 3-D tool output an answer, you are
going to be in for a rude awakening some day when your system fails. You
really have to understand what the expected results should be (by hand
calculation, simple 2-D model, etc) when building a complex model and then
test the model (DC, Frequency domain, Transient) to ensure that a good model
has been built.

Just my 2 cents

Doug



Douglas J Burns
Vice-President, Consulting Services
6 Clock Tower Place
Suite 250
Maynard, MA 01754
978-461-0449 x14
dburns@xxxxxxxxxx


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of steve weir
Sent: Wednesday, August 09, 2006 4:15 AM
To: Xilei Liu; gianguida@xxxxxxxx; steven.salkow@xxxxxxxx;
si-list@xxxxxxxxxxxxx
Cc: dburns@xxxxxxxxxx
Subject: [SI-LIST] Re: R: Re: Wire bonding


Celine, it depends on how well the spacing is controlled to nearby 
metal.  The joint itself is not generally a tolerance problem.

Steve.
At 01:09 AM 8/9/2006, Xilei Liu wrote:
>How accurate can these models be for a bond wire with its
>unpredictable soldering conditions or other joint condictions in the 
>real world?
>
>Regards,
>Celine
>
>
>>From: <gianguida@xxxxxxxx>
>>Reply-To: gianguida@xxxxxxxx
>>To: 
>><steven.salkow@xxxxxxxx>,<weirsi@xxxxxxxxxx>,<si-list@xxxxxxxxxxxxx>
>>CC: <dburns@xxxxxxxxxx>
>>Subject: [SI-LIST] R: Re: Wire bonding
>>Date: Tue, 8 Aug 2006 18:09:55 +0200
>>
>>dear Steven,
>>I would disagree with you
>>up to date 3D simulator does not require several days just to setup a 
>>model in addition if you can get a good support and a training I am 
>>quite sure it is possible to setup several model in one day :-)))
>>
>>Respectfully
>>Giancarlo
>>-----Messaggio originale-----
>>Da: si-list-bounce@xxxxxxxxxxxxx per conto di Salkow, Steven
>>Inviato: mar 08/08/2006 17.35
>>A: weirsi@xxxxxxxxxx; si-list@xxxxxxxxxxxxx
>>Cc: dburns@xxxxxxxxxx
>>Oggetto: [SI-LIST] Re: Wire bonding
>>
>>David:
>>3D field solvers are very hard to use and require several days to even 
>>set up a simulation. There are people that are experts at this and 
>>affordably charge by the hour. Here's a contact
>>Douglas Burns ,Vice President, Consulting Services/Chief Consultant
>>,Signal Integrity Software, Inc. ,6 Clock Tower Place ,Maynard, MA 01754
>>,978-461-0449 x14 ,dburns@xxxxxxxxxx , CCA pcb design
>>
>>By the way, 3D field solvers are very expensive and have a steep 
>>learning curve.
>>
>>Another approach is to find someone using the same package you are 
>>using that has an IBIS model for it. The pin parasitics should be in 
>>the ASCII file. (many IBIS files are available for download)
>>
>>Steven Salkow
>>Senior Staff
>>Lockheed IS&S
>>3130 Zanker Rd, San Jose
>>Ca. 94588
>>(408) 473-4058
>>
>>steven.salkow@xxxxxxxx
>>salkow@xxxxxxxxxxxx
>>
>>
>>
>>
>>
>>-----Original Message-----
>>From: si-list-bounce@xxxxxxxxxxxxx 
>>[mailto:si-list-bounce@xxxxxxxxxxxxx]
>>On Behalf Of steve weir
>>Sent: Monday, August 07, 2006 8:24 PM
>>To: dan1_st@xxxxxxxxx; si-list@xxxxxxxxxxxxx
>>Subject: [SI-LIST] Re: Wire bonding
>>
>>David, unless you have considerable experience with structures that 
>>have very similar geometry you can not estimate reliably accurate 
>>numbers.  5Gb is fast enough that you have the potential to excite 
>>some less than amusing resonances that can keep you from transferring 
>>much energy between your sources and intended loads.  Your packaging 
>>house may be able to help you.  Otherwise you need to find 3D field 
>>solver software and someone who knows how to drive it.
>>
>>Steve.
>>At 02:22 PM 8/7/2006, david stern wrote:
>> >HI
>> >
>> >We are designing an electro-optical element for
>> >infiniband optical transceiver.
>> >We are using a driver as a dye chip with wire bonding process.
>> >The 1 mil wire is 1mm long. One side of the dye chip
>> >is using 2 wires for differential input
>> >and on the other side  we use 1 wire surrounded with 2
>> >GND wires for signal.
>> >Our devices are design to work at baud rate of 5Gbps.
>> >
>> >I tried to get information on the web about signal integrity for 
>> >high speed wire bond without any success.
>> >
>> >       1.   Where can I find material about SI for wire
>> >bonding?
>> >2.      how shall I  define wire bond in simulation? shall
>> >I defied it as inductor?
>> >3.      How shall I calculate the impedance of the wire
>> >bonding?
>> >4.      Are there cases were wire bond can be neglect due
>> >to the fact that it place right after the driver or
>> >        right before the receiver?
>> >
>> >
>> >Thanks in advance
>> >David
>> >
>> >
>> >
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