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Andreas Thiel's CAD Tools Flame War Page
[German
version] [English version]
! This is the translation of the
german original. It might not be quite the same in all passages.
Contents
- What's it all about?
- Introduction
- Cadence
- EAGLE
- Incases
- Intercept
- Mentor Graphics
- OrCAD
- Protel
- Specctra
- Tanner Tools
- Veribest
- ViewLogic
- Xynetix
- CCT and Quad
- Zuken Redac
- Non-toolspecific opinions
This page originated over discussions for the
"ideal" CAD tool for PCB design at the Electronics
Laboratory (IfE) of the Swiss Federal Institute of
Technology (ETH) in Zurich, Switzerland. If certain views given here do not reflect
the truth we will gladly add the opinion of tool developers.
CAD tools for the electronics sector are generally a
nuisance for the user. For no other piece of software would it be accepted to pay such
horrendous sums of money for such poorly programmed, poorly documented and faulty
programs. Only to give an example: For a mechanical engineer it is absolutely
incomprehensive that a certain tool can survive on the market which cannot
produce output that can be processed by a manufacturer.
Over the time the Electronics Laboratory has used
several toolchains:
- Cadence (Concept, Allegro, SigNoise, etc.)
- Viewlogic (Powerview/Viewdraw), Xynetix
(EDA Navigator, Encore BGA/MCM), CCT (Specctra Router), Quad (Precise, XTK,
TLC)
- Protel (Advanced Schematic, Advanced PCB,
Advanced Route)
- Zuken Redac CADSTAR
These have been reduced to Protel and Cadence at
present.
This page is meant to be a forum for discussion. We
want to present esecially the ideas, experiences and requirements of the users.
It is not meant to be a FAQ, but we target at improving the knowledge about the ever
increasing diversity of tools available today. When sending me email, everyone can take part in the discussion
(on request anonymous). I don't think this is the right place for insults or accusation,
but merely as a constructive forum to give students an optimal education. I will then
include your input here on this page. I have evaluated several toolchains available and
will start the discussion with views and observations. Certainly all the (dis-)advantages
listed are incomplete and constantly changing. Many information given here has to be
regarded as a time sequence, meaning that the first lines are the oldest and the last the
most current (mostly on the opinion parts).
A further goal of this page is to give those
embarking on a new design project a guide to choos the "right" toolchain.
We are observing that none of the over 40 student
projects running at the IfE this semester are using the layout tools supported by the Department of Electrical Engineering (D-ELEK) (Cadence).
Protel is widely used and regarded as an easy to use, all in one solution. This drastic
change is the actual event that made us developo this collection of data and opinions. I
have the feeling that emotions are going very high at the moment and this page is a try to
keep discussions based on facts, opposing the rather radical title.
All remarks regarding pricing are only true to some
extent for us as an educational institution, as we can obtain almost any product at an
extensive rebate. But there i sno appearant reason why a Cadence Allegro without
Autorouter is supposed to cost alsmost 100x as much as Protel's Advanced PCB.
In my opinion no tol can fullfill all requirements.
But it should not be necessary to begin every design on a new toolchain. Maybe it is
possible to get a little organisation into this true "CAD-jungle". In out house
there are primarily three groups of users: Most designs are started by the notion
"oh, let's just make a printed board for this...". It is sure that this type of
approach calls for the shortest development cycle, without having to set up and learn the
design flow forst. Secondly there is a scientific aspect in research and development of
the most modern CAD workflows available. Be it be in scientific research or from a more
educational perspective, introducing the toolchains and design flows to students. Here,
not the design, but the design flow is the actual objective. A compination of different
standalone tools is most probable to achieve the maximum perfomance possible. A third case
are designs, that are so complex that they call for the most sophisticated tools, a
spectrum of features and performance most "cheap and simple" tools (even though
they are quite powerfull) cannot deliver. Especially the area of post-layout simulation
reaches the limitations of state of the art tools quite quickly, mostly due to the fact of
missing simulation models of single devices. Nontheless a well established and recognized
toolchain could benefit to the overall situation.
Some of the tools listed are only available on PC's,
some only on UNIX (too bad practically none under Linux). A UNIX tool is probably the most
adequate for our infrastructure. But industy is moving strongly into the PC based
solutions.
Cadence Design Sytems has aquired OrCAD in May 1999 to
continue the product as it's "shrink-wrap solutions", eventually merging it with
Allegro Studio as it's WinNT package.
Almost the whole toolsuite (IC and PCB tools) of
Cadence Design Systems has been made available to the Department
of Electrical Engineering through the Design Center (DZ) and is beeing
supported by them as well (Hubert Kaeslin, Ruedi Köppel, Andi Wieland). The DZ is also offering courses and a
library of components that is maintained and can be extended by Ruedi upon request.
The Cadence tools Concept HDL for schematic
entry, Allegro for placement and manual routing and Specctra (formerly CCT) for automatic
routing are most suitable for PCB board designs. There are a whole set of tools for
simulation for analog and digital simulations available. A post-layout analysis
(crosstalk, etc.) is possible too. Last but not least tools for programmable logic are
available.
Recently Cadence has started to offer a stripped
down version of their PCB toolchain for WinNT (Allegro Studio) at a very moderate
price. ~USD 10k will get you a six layer allegro, specctra autorouter, library interface
and schematic entry. It can be enhanced with other Cadence packages at the regular
pricing. OrCAD is designated to be the lower end solution.
- Advantages:
 | Very extensive toolset, especially in the area of
electrical simulation. |
| Unnumbered possibilities to configure. (There is
probably nothing that you cannot somehow accomplish with Cadence.) |
| Large in-house library of components. |
| In-house support group (courses, hotline, maintenance
of libraries). |
| The system is based on a PHYSICAL-PART-TABLE.
This means that all component information is incorporated into the schematic and evaluated
by Allegro and other tools later. |
| Cadence is establishing itself more and more as the
industry standard in the EDA world. It seems as if Cadence wanted to clean up on the
market for the low-end. The acquisition of OrCAD shows this tendency quite clearly.
Allegro is also available at a very competitive price (~USD 10k). |
|
- Starting with release 98 (PE13) the tools are
converging into a Windows like look and feel, giving them a basic resemblance and
similarity in the user concept. Users familiar with the indescribable "look and
feel" of the former releaseswill know to appreciate this move.
|
Disadvantages:
| Manual and automatic routing in Allegro are not as
comfortable as in other tools. Maybe this will improve with the integration of Specctra. |
| The complexity of the tools calls for a quite
extensive amount of learning and getting used to. This can be quite cumbersome. |
| The tools require very carful and detailed work.
Small discrepancies, that can easily sneak in during a students term project often have
fatal results. |
| The name Cadence on the product does not mean it's
Cadence inside. Many tools have been acquired from other companies over time. The workflow
and interaction can thus be quite rough in some cases. This has greatly improved in
PE13.0. But this also means that the WinNT version is more stable and faster than the UNIX
version. The latter is only emulating the NT environment and running a clone of the NT
version on the UNIX system. Funny. |
| Cadence is the most expensive tool available today
(only Allegro without schematic entry, autorouter, etc. ~USD 100k). |
Opinions:
| Cadence is surely a very extensive tool, which is
also appearant in the usability. Momentarily (release 97) the user has access to
practically all functions via the program manager. This does certainly not enhance the
overview of the design flow for the user. A frontend with a given design flow
(Concept->Allegro->Autorouter->Production Data) would be very preferrable for the
user. This would probably hide many of the speciality functions that Cadence offers over
othe products, but would not matter for everyday type of designs. (Patrik Eggenberger,
IfE) |
| Functions (i.e. autorouter) benefit the beginner
only if he knows under which circumstances he can use them (i.e. default settings). This
calls for extensive testing of these functions prior to release. (Patrik Eggenberger,
IfE) |
| Cadence definately needs a great deal of support
to show it's huge potential! (Patrik Eggenberger, IfE) |
| New versions are a very dangerous thing with
Cadence. It takes years untill a new release has been debugged sufficiently by other
users, that there are no more terrible surprises happening in a design. It seems as if
Candnce is pursuing a "banana-strategy", letting the tool ripe with the
customer. Use only very well tested versions! (Andi Thiel, IfE) |
| It is absolutely incomprehensible why Cadence
never seems to get a grip on certain base functions and capabilities. Among these are for
example are auto voids (shapes are regularly conflicting design rules), the slide
mechanism (regular corruption of the database) or the contacting of vias to crosshatched
shapes (DRC if via center is not directly on crosshatch line). (Andi Thiel, IfE) |
|
- The amount and content of documentation varies
greatly over time and origin of the tools. It is often usefull if you have access to older
documentation in addition to the current Cadence docs, like old CCT Specctra user guides,
to understand the why's and how's better. (Jan Beutel, IfE)
|
|
- The new "look and feel" as well as the
integration of the Project Manager in PE13 has greatly added to the initial start up time
and general usability for the user. (Jan Beutel, IfE)
|
System:
| UNIX |
| WinNT |
- CadSoft offers user friendly, powerful and affordable
solutions for PCB design, including schematic capture, board layout, and autorouter.
-
- Opinion:
| I still use EAGLE (MS-DOS version without
autorouter) for small projects. It is a very affordable sytem and very simple to operate.
All tools interact with each other well and the system never hangs. If a component or
capability of a tool is missing it can be integrated by writing external scripts. |
| Routing can be done very comfortable, thus an
autorouter is not necessary for small boards. It would probably be quite cumbersome and
time consuming to set up the parameters for an autorouter. (Reto Baettig, SCS) |
- System:
Supposedly a good package when it comes to high
level design rules. One of the few on the market with it's own autorouter. The company has
it's heritage in EMC driven design and simulation.
- System:
| UNIX |
| WinNT |
A group of former Mentor developers set off to
create a whole new suite of tools. Downloadable applications and documentation give EDA a
whole new approach. The PCB application Pantheon interfaces to OrCAD, Viewlogic's ViewDraw
and Mentor's Design Architect for schematic entry, Specctra and Zuken Redac's Route Editor
for autorouting. An Intercept schematic entry tool is under way.
The integration of Xynetix Encore PCB should give an
ample amount of enhanced design features to this product.
- System:
The other biggy out there. Mentor offers an
extensive suite of almot everything necesssary at an equally extensive price range. Many
users seem to be dissatisfied, though.
- System:
| UNIX |
| WinNT |
Cadence Design Sytems has aquired OrCAD in Mai 1999.
A well accepted mid-range suite of PCB solutions.
- Disadvantges:
| Only 1µm base resolution. Better than what it used
to be, but certainly not nice. |
- System:
| Win95/98 |
| WinNT |
On recomendation of Geert Bernaerts Protel is
available to everyone interested to evaluate at IfE. It will be decided if and how many
licenses are to be purchased by IfE.
Protel offers AdvancedSchematic for schematic enty,
AdvancedPCB for manual layout and AdvancedRoute for automatic routing.
- Advantages:
| All tools are integrated into a toolsuite, only the
autorouter Advanced Route (still) remains as a standalone application. |
| Seems to be easy and straight forward to learn. Most
probably an effect of the Windows like look and feel. |
| Can im- and export a large amount of file formats. |
| Extensive component libraries available online. |
| Interface for the Specctra autorouter |
| The newest version limits the resolution to 1/10000
inch (0.254µm). That should be sufficient for MCM designs. Rounding errors when using a
metric grid system should be neglectable (Protel always uses english base units). |
| Cost effective. (Complete package including AdvancedRoute
Router under USD 8k) |
Disadvantges:
| Limited capabilities when using blind and burried
vias. This is a problem if you are using modern build-up technologies. Especially the
autorouter Advanced Route does not function with these vias. Maybe this problem can be
surpassed by using the Specctra Router. It is unclear at the moment if data containing
blind and burried vias can be read back to Protel correctly. This would definately top out
CADSTAR in the price since a Specctra licence with hybrid and design for manufaturing
(DFM) options is USD ~20k. |
| Protel 98 does not support Specctra anymore. At least
it is not visible on the Protel web pages. Thus the support of bbvias remains unclear. |
Opinion:
| There are numerous PC based tools with a similar
philosophy as Protel (OrCAD, TangoPRO, P-CAD, etc.). Each one of them has it's specific
strenghtes and weaknesses. All do not support advanced design features such as bbvias in a
very promising way. They are totally sufficient for normal PCB's. (Andi Thiel, IfE) |
| The release of Protel 98 is closing in on the
standard with PC based tools: lot's of rebootig, corrupted databases, too much featurism.
This and more can be read in the according newsgroups. Too bad! (Andi Thiel, IfE) |
| Libraries, extensive support and demos available
for download ease a head start. (Jan Beutel, IfE) |
Supposed to be a very consistent design flow for
multi chip modules and high density packaging. Used by IMC and IMEC.
- System:
| UNIX |
| WinNT |
Extensive and scalable line of Windows based tools
for physical design (analog and digital) as well as some simulation. Interfaces to many
other, especially Mentor's line of products. The company and the tools all derive from the
popular Intergraph systems.
One of the few advanced systems, you can actually
shop for online (is it any good?).
- Advantages:
| An all in one tool suite. Same look and feel.
Consistent setup and parametrisation. |
|
- Own autorouter available. Seems to be very good
performance. Probably a heritage of Intergraph.
|
|
- Scalable performance through different levels of
applications (is it an advantage?)
|
Disadvantages:
| No scripting or command line interface. This makes
automatisms (i.e. library generation) very hard to realize. |
| Too many bit's and pieces to the toolsuite. The
scalability leaves you dealing with many parts of the system that are actually destined to
be used at a different place (i.e. corporate database with remote locations). |
| Unclear separation of Veribest and the underlying
Bentley Microstation CAD system. This leads to confusion and inconsistent operation of
tools. (Why is there an underlying MCAD system?) |
|
- Only certain bbvia combination are supported, such as
when doing a symmetrical build-up with one bbvia in the core. No reliable future support
of advanced design features.
|
Opinion:
| A very sophisticated approach at first sight.
Attractive pricing and options (scalability) add to the positive first impression. The
closer look revealed that it is certainly not good for any other designs than standard
pcb's. The MCM add-on and the advanced design rule options are so limited. (Jan
Beutel, IfE) |
|
- The Veribest sales and support staff is
definately not aware of the demands available in advanced packaging technology today.
(Jan Beutel, IfE)
|
- System:
| Win95/98 |
| WinNT |
Xynetix sold it's PCB layout software business (Encore PCB)
to Intercept Technology in October 1998.
The remaining business of Xynetix (Encore MCM, EDAvalidator and EDA Navigator) has
been sold to Avant! in May 1999.
Cooper & Chyan Technology (Specctra Router) has been
aquired by Cadence Design Systems in May 1997.
This toolchain is a solution that was originally set
up for the design of multi chip modules. Viewlogic's ViewDraw is used for the schematic
entry, Encore MCM/BGA and the Design Floorplanner for manual route, the Specctra
Autorouter for autoroute and Quad can do the electrical simulation. Furthermore a license
for the Xynetix EDA Navigator is available. This is a tool that helps in the planning
phase of a MCM design (electrical and thermal behavior, routing density, layers required,
tradeoffs, etc.) It is possible to do standard PCB prints, once you got familiar with the
different naming conventions, but actually this is the optimum you can get for MCM design
off of a tool chain today.
In general we have to ask the question if all the
comfortable MCM specific additional functions are really worth the money, if with a little
more work done by hand and not too many designs per year you can get to the same results.
Under scientific aspects the goals and principles that drive the development of the EDA
Navigator are by far more, what is known of today from other vendors (Cadnece). This is
certainly an oportunity to see what is still up ahead in the future in the ECAD world.
Viewdraw is not regarded an intuitive tool. It has
been accomplished to establish yet another confusing definition of mouse useage. Tools
that can be used to develop component libraries are missing, especially for high pincount
components with high similarities. A good thing is, that files are set up in a simple
manner and all in ASCII coding. A few lines of Perl (actually an integral part of most CAD
tools out on the market today!) help along to ease this situation. But is absolutely
incomprehensible why the UNIX version is more than twice the price of the Windows version.
The printouts will not receive a recommendation for quality or visibility either, no
color, no usage of postscript fonts.
- Advantages:
| Very powerfull set of tools for layout (Xynetix,
Specctra, Quad). Especially the support of semi-automatic and automatic routing is very
dominant. |
| Full support for MCM and BGA designs (wire-bonds,
bbvias, etc.). This is really very impressive, at least we have not seen any better to
date. |
| The only tool we know of, that allows multiple
physical pins to be assigned to one logical pin. This is especially important when bare
dies use multiple bond wires for the same logical signal. |
| It outputs GDSII, if you buy the option. Same applies
to postscript. |
| The EDA Navigator is a very interesting advance in
the direction of design planning. |
Disadvantages:
| Schematic entry with ViewDraw is very cumbersome
compared to Protel or Concept, especially the generation of components is ineffective and
not transparent. |
| The quality of printouts in ViewDraw is unacceptable.
No postscript fonts, no postscript color, the own fonts are almost illegible. |
| The design rule check is not working. This is the
great disappointment. It is possible to enter 100's of constraints, but even an
interrupted groundplane is not detected. |
| There is no physical parts library. Unpackaged chips
do not make much sense to have in a library since they look different every other six
months or so, but just to have an example an IPC library would be quite nice to have. |
| No unified tool suite. That makes the transition from
tool to tool rather difficult duricng the design flow. Much like Cadence pre PE13. |
| Pricing isn't very attractiv either. A single node
locked ViewDraw, Encore MCM/BGA, Specctra Router (Windows) setup is way over the USD 100k
range. |
| Xynetix is reassuring us that the Specctra router
will be available in the future, but should be acquired directly from Cadence. Knowing how
Cadnce keeps their promises in regard to Mentor makes us rather sceptical. |
| There is no clear support of netlists: Either there
is no automatic pin/gate swap with DRC (packages defined only, no parts in Encore) or
there is no unique netlist due to a new generation of power and ground nets in the part
files (this is dangerous!!!). I don't really want to know, what the Xynetix developers
thought when they set up this crap. |
| Minor malfunctions:
 | No WYSIWIG. Gerber output is not identical to the one
shown on the screen. This is especially true for shapes, power and ground. |
| Level/Layer concept is quite inconceivable. |
| Too many bit's and pieces to the tool involved:
ViewDraw - Netlist - Update - Encore - Floorplanner - EDAArtist - Specctra -
Fabrication Backplane needs an awfull lot of configuration work (much like Cadence). |
|
Opinion:
| The inconsistent interaction of too many tools
and very different userinterfaces make this toolchain incredibly hard to use and maintain.
The same mix that is appearant on the userinterface turns out when you delve into the
datastructures employed. A whole external framework supplied by the user is necessary to
develop and maintain a coherent design database. (Jan Beutel, IfE) |
| Viewlogic's ViewDraw is a pain to use on UNIX. It
is supposed to be easier on Win, but why does it seem so incredibly difficult to create
and visualize a logic database, actually all we want of schematic entry. Why are
identifiers and names still restricted to a few characters only? (Jan Beutel, IfE) |
| A close encounter with Encore MCM/BGA ended in a
nightmare of functional errors. No WYSIWIG. No functioning DRC. No minimum metal
structural sizes defined or even checked. Shape boundaries are not to specification.
Clearance to the board outline and metal keepouts cannot be defined and/or are not to
scale. Different definitions of the design rules in Design Flooplanner and Encore. No
logic master for a design, i.e. netlist! Phew... Oh, by the way, all this only turned up
after spending half a year with the tools. (Jan Beutel, IfE) |
CADSTAR is mostly used for designs at SCS. It seems to posess most features necessary and has been
on the market for a long time. Maybe the actual users can tell more about it.
- Advantages:
| Integrated toolchain, only the autorouter (same like
Protel) is still a seperate product. |
| Zuken says, they have the best autorouter available
on the market. |
| 1/100µm base resolution is sufficient for MCM
designs |
| Simple to use user interface (Windows) |
Disadvantages:
| The demoversions I have seen so far would crash
often. I have heard this is also true for the full version. Maybe this has been repaired
in the meantime? |
| There are no component libraries available. The
contents of the Zuken webpages only open up once you have signed the license/maintenance
agreement. |
| It is a pretty self contained solution. Not many
possibilities for im- and export. But many other third party tools can read Zuken Redac
fileformats. |
| The pricing is very hard to understand. Mainly it is
dependant on the number of routeable nets. A full license with autorouter sells for about
USD 20k. |
Opinion:
| The value of libraries containing physical
component data is not clear. Especially for the automatic placement of components the
manufacturers have very specific and by large diverging desires and guidelines of how to
design a specific pad layout. If prototypes are only assembled manually, which is quite
normal in our environment, the quality of libraries supplied (i.e. by Protel) is totally
sufficient. (Andi Thiel, IfE) |
| The value of libraries containing physical
component data is very high, when they are developed and maintained consistently and with
expertise. They allow the assembly of designs with different manufacturers. All components
supplied by the DZ are according to the guidelines issued by the Chair of Reliability in
their report K12 dating of 23.10.96 by G. Grossmann. (Ruedi Köppel, DZ) |
| Component pad layouts should never be designed
according to the guidelines of an assembly manufacturer. Who will give a guarantee that a
second source supplier can assemble these? A second source is abolutely required in
industry. (Ruedi Köppel, DZ) |
| The EDA support at the DZ has always tried to
guide towards a Design For Manufature with the projects supported. Many design rules have
been incorporated into the CADENCE environment supplied. These would also have to bee
incorporated into a second product supported by the DZ. (Ruedi Köppel, DZ) |
| Imany of the CAD tools described use the Specctra
autorouter. Cadence has aquired CCT (COOPER&CHYAN TECHNOLOGY,INC.) at the
beginning of the year and it is not known how long this product will be available (to
interface) with other CAD toolchains, their direct competitors. (Ruedi Köppel, DZ) |
E-Mail your comments to thiel@ife.ee.ethz.ch
Back to my homepage
Maintainer: Andreas Thiel <thiel@ife.ee.ethz.ch>
Translator: Jan Beutel <j.beutel@ieee.org>
Last Update: 03/06/00 10:55:39 PM
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