Tools for Materials Characterization


SYMMIC Frequently Asked Questions


Who developed SYMMIC?
SYMMIC, the template-based thermal simulator for monolithic microwave integrated circuits, is a product of CapeSym, Inc.
How long has SYMMIC been on the market?
SYMMIC was first demonstrated at the 2008 exhibition of the International Microwave Symposium, and has continued to be improved over the years. Version 3.1.6 was released in February of 2024.
Where may the software be purchased?
The software may be purchased directly from CapeSym, Inc. and from select resellers. Please Contact Us for more information.
Is the software available in my country?
SYMMIC is available world-wide, except for a few countries specified in the U.S. Export Administration Regulations. The software may not be exported or released in any way to a country designated AT1 in the Commerce Country Chart.


Where can I learn how to use the software?
One of the best ways to learn about the software is to go through the on-line tutorial videos.
How can I read the SYMMIC Users Manual?

The users manual, which contains detailed examples, is available online at, but a .pdf version is usually also available for the most recent major release. Please Contact Us if you would like a copy.

The Help menu provides access to the latest version of the Users Manual in .chm format. If the Help window opens but is blank, the .chm file might be blocked by Internet Explorer. To remove the block, right click on the .chm file in the Windows file viewer/manager, select Properties and then press the Unblock button at the bottom of the General tab. If there is no Unblock button present, the file has already been unblocked for the local machine, but make sure that it is not being accessed over the network where it might still be blocked on other machines.

Does CapeSym offer on-site training classes?
Yes. Please Contact Us for details.


How is the software licensed?
SYMMIC is licensed for a finite lease period, usually 1-3 years. Both machine-locked and floating (network) licenses are available. A "floating" license allows the software to run on any computer with network access to the license server, within a 30-mile radius.
What is the cost of a license?
Please Contact Us for a quote.
What support is provided with a license?
Licensees receive email support for all software bugs and any issues with CapeSym templates (input files), as well as the latest releases of the software, device models, examples, and documentation.
Which license manager is used?
Licenses are software-enforced using the Reprise License Manager, which runs on both Windows and Linux. FlexLM cannot be used to manage licenses.
Can the software be used on a virtual machine?
The application can run on a virtual machine but the license server that provides floating licenses to each instance needs to be anchored to a real machine. Reprise License Manager is capable of running on a virtual machines, but this behavior is disabled to prevent running multiple copies in an enterprise. Please Contact Us if you need to have the license server run on a virtual machine.
Can the software be used via Remote Desktop?
Yes, the software may be used remotely from another machine.
Can I try the software before I buy it?
Trial licenses for the full version of the software are often given to prospective customers with the understanding that the licenses will be used only for evaluating the software and will not be used to support any commercial activities. For more information please Contact Us.
How do I activate a license?
When the software is started after installation it will display the Host Id for the machine. Email this host id to the SYMMIC support address listed in the dialog. For a floating license, information for the machine that will run the license manager is required. A license file is returned as an email attachment.
How do I install the license file?

For a machine-locked license, copy the license file into the SYMMIC program folder, overwriting any existing license file. For a floating license, place the license file in the program folder where the rlm.exe is located on the server that manages floating licenses. Any client machine that will request and use the floating license should have, in the SYMMIC program folder, a license file that contains just two lines:

SERVER servername serverhost

ISV capesym

This directs the software to request the floating license from the server.

Can the license manager be used on non-Windows platforms?
Yes. The license manager for any operating system may be downloaded and installed from the End-User Support Bundle on Reprise's website. In addition to the license file, you will need to copy the capesym.set file from the SYMMIC distribution which specifies which platforms are supported. For a platform that is not currently supported, please Contact Us.
Do I need a separate license for GDS2SYMMIC?
GDS2SYMMIC uses the same license as the SYMMIC graphical user interface, so you can run it without purchasing an additional license as long as the SYMMIC application is not running. The GDS2SYMMIC code is no longer maintained and the utility will not be available in future releases.

System Requirements

What are the system requirements?
  • - 64-bit Windows
  • - x64 compatible processor; 4 or more cores recommended
  • - 32Gb RAM recommended
What versions of Windows are compatible?
SYMMIC is compatible with 64-bit versions of Windows Vista, 7, 8, 8.1, 10, and Server 2012, 2016, 2019. SYMMIC is no longer supported for 32-bit or Windows XP operating systems.
Does the software run on Linux?
The command line version of SYMMIC, called xSYMMIC, is currently available for both Linux and Windows. SYMMIC's graphical user interface is currently designed to run on Windows platforms only.
What if the software crashes on my computer?
If the graphical user interface often crashes when displaying a template, mesh, or plot, or when changing parameter values (which causes the template to be redrawn), a likely culprit is faulty OpenGL drivers. You may need to update the driver of your display adaptor to eliminate this behavior. See readme.txt in the program folder for more information.
How much memory does the solver require?
To compute solutions to single device problems at the fastest speed using the in-core solver, plan for at least 5.5 Gb of physical RAM per million nodes. (The number of unique problem nodes is reported to the console when the problem is meshed.) To solve MMICs containing multiple devices, memory usage can be reduced to a fraction of this amount through the use of both superposition and out-of-core storage of the factorization of the FEM matrix.


How fast is SYMMIC compared to other solvers?

For a comparison made early in the development of SYMMIC please see: Comparing SYMMIC to ANSYS and TAS. The performance of SYMMIC has continued to improve over the years. Problems with a single FET solve in a few minutes. For example, version 2.9.0 could solve half of a 98-gate FET on a 2x4mm MMIC (2.3 million nodes) in less than 3 minutes on a Intel Xeon E5-1620 (3.6 GHz) desktop workstation with 32 Gb of RAM. Resolving the gate temperatures on MMICs containing multiple FETs can take a little longer. An XBand amplifier with 3 FETs of up to 24 gates took about 10 minutes on the same machine.

Version 3.x introduces further enhancements that can significantly reduce solution and post-processing times. The 2.3 million node, 98-gate FET problem takes just 130 seconds to run in version 3.1.0 on the same hardware, while the Xband amplifier runs in 512 seconds. Version 3.1.0 can solve 270 million simultaneous equations in 45 minutes on a cluster of eight machines running in Amazon Web Services. This level of compute power is made available to all SYMMIC customers for a low hourly rate.

Does SYMMIC take advantage of multiple cores?
Yes. The SYMMIC solver will run faster when there are multiple cores in the system. Support for cluster computing is available starting in version 3.1.0.
What if a simulation takes a long time on my computer?

You may have insufficient memory to solve the problem quickly using the in-core solver. Normally SYMMIC uses a fast (but memory intensive) algorithm to solve the problem, but when there is insufficient memory available this can lead to virtual memory paging causing a big slow-down. When the memory field of the statusbar at the bottom of the SYMMIC window is displayed in red text, there may be insufficient physical memory to solve the problem quickly. In this case, the out-of-core or PCG solvers should be used to solve the problem. Use the Show mesh button the Model Check dialog to see memory estimates for all solvers.

Why is SYMMIC producing higher temperatures than measured?
It is well-established that thermal simulations provide evidence for higher temperatures in small devices than can be physically measured. For a discussion see: Green, D. S.,, "GaN HEMT thermal behavior and implications for reliability testing and analysis," Phys. Stat. Sol. (c) 5, No. 6, 2026-2029 (2008). However, when measurement-like averaging is used on simulated solutions, SYMMIC results are in good agreement with measurements, as shown in the application notes:

Simulations Versus IR Measurements

Simulations Versus Micro-Raman Spectroscopy

Why is SYMMIC producing higher temperatures than my current solver?
SYMMIC users often get higher temperatures than they had been getting in TAS or ANSYS *because* they were using coarser meshes with those other simulations. In one of the application notes we show that ANSYS and SYMMIC give identical answers with the same mesh and boundary conditions. Every thermal analysis simulation should include a mesh density study to ensure accuracy of results. Template designers at CapeSym, Inc. validate mesh density to ensure that our templates will give excellent accuracy (i.e. halving the mesh element size will not significantly change the results).
How does SYMMIC compare to Cooke's model?
Although lots of MMIC designers use analytical models for thermal analysis, the Cooke model will not be as accurate as a finite element model of the same problem. Because of the parameterization in the template-based approach, MMIC designers can setup a thermal analysis just as easily in SYMMIC as in a spreadsheet. The results obtained by SYMMIC will be more accurate over a much broader range of dimensions.
Has SYMMIC been compared to Darwish's model?

Yes. For the detailed comparison, please see:

Using a FET Template for Thermal Analysis

Physics Capabilities

Are temperature-dependent properties simulated?
Temperature-dependent material properties are fully supported, including thermal conductivities, specific heat capacities, densities, and emissivities.
Are orthotropic materials simulated?
Thermal conductivities can be orthotropic, having different (temperature-dependent) values in the x-, y- and z-directions, or isotropic, having the same (temperature-dependent) values in all directions.
Is transient analysis included?
Yes. Both steady-state and transient thermal analyses are included with a single license.
Is pulsed power simulated?
In addition to continuous power, SYMMIC transient thermal analysis may include pulsed power which is switched between two different power levels with a user-specified duty cycle.
Does the software simulate convection?
No. The conduction solver includes film and radiant boundary conditions, but does not directly model fluid flow.
Is radiation between surfaces simulated?
No. Only radiation to ambient is simulated.
Does the software directly simulate the effect of temperature on power dissipation?
Yes. In addition to the temperature-dependent change in material properties, the solver can also directly modify flux based on local temperature according to the formula: where T is temperature, and T0 and n are user-specified parameters.
Does SYMMIC compute thermal resistances?
Yes. SYMMIC will compute a thermal resistance matrix for each transistor through each layer in the stackup and output this both in equation form and as a circuit in netlist format. This output will be generated whenever a simulation is run with the "Record equivalent thermal impedance" flag checked. The resulting thermal resistance network can be used as a compact thermal model for coupled electro-thermal simulations. See the application note Electro-Thermal Analysis using SYMMIC with Microwave Office for details.
Does SYMMIC calculate thermal capacitances?
Yes. By running a transient analysis after a steady-state analysis, SYMMIC will compute an equivalent RC thermal circuit in netlist format.

Model Development

What are template, device, and layout?
A template is an XML file which describes a parameterized thermal model. A device template describes the thermal analysis problem to SYMMIC with sufficient detail to allow the software to compute a finite element temperature solution to the heat transfer partial differential equations. Often a device template models a single transistor. A layout template is literally a layout or arrangement of device templates, each sharing some common layers (such as the substrate layer in a MMIC). A layout template can be converted into a device template through the "Export" operation.
Can SYMMIC interface to my electrical CAD tool?

Scripts are available to facilitate thermal analysis from Microwave Office (MWO) or ADS (EEsof). ADS script facilitates exporting device locations from a layout in Keysight's EEsof to SYMMIC for thermal analysis. MWO scripts easily export layouts and power to SYMMIC, and provide the following additional functionality:

  • Export thermal resistances to MWO scripted equation for schematics
  • Iterative CW electro-thermal analysis with scripted equation
  • Iterative electro-thermal with SYMMIC in the loop
  • Export RC thermal network for incorporation in transient electrical simulations

  • Please see the Electro-Thermal Datasheet for more details.

    Can SYMMIC model packages and PCB stacks?
    Yes. The layout of exported devices allows the hierarchical construction of complex subsystems.
    How do templates relate to PDKs?
    You can think of a set of device templates as representing the design kit for a process from the thermal perspective.
    Are PDKs available for foundaries?
    There are currently no publicly available foundary PDKs, although CapeSym has developed foundary-specific proprietary templates for some customers.
    Are templates provided with the software?
    Yes. A set of generic device templates is installed with the software. These templates can be reconfigured to match a lot of different devices, by simply changing parameter values. Additional templates are made freely available for download to all licensed SYMMIC users. Several worked examples using the generic templates in MMIC designs and subsystems are also publicly available.
    Where are the installed templates located?

    If the defaults were used during installation, look in the folder:

    Windows XP: C:\Documents and Settings\Username\Application Data\SYMMIC\

    Windows Vista/7/8/10: C:\Users\Username\AppData\Roaming\SYMMIC\

    Alternatively, search for "FET.xml", or reinstall the software and select a better template location.

    Why is a template usually only half of a transistor?
    If a device is symmetical, the model can be simplified by using only one of the two identical halves. Furthermore, if the symmetrical device is placed in the center of a die, then the solution on either side of the line of symmetry will also be identical. Thermal analysis of half a device will be faster than the whole device but still give the same amount of information.
    How can a whole be created from the half?
    The model of a whole transistor (located asymmetrically in a die) can be created from the template of half of the symmetrical device by using it in a layout with the "Mirror" flag checked.
    Do the installed templates define the limits of the software?
    A given template represents choices made by the template designer rather than limits of the software. A template will have a certain number of layers in the stackup and parameters with specific limits; a different template may have completely different layers and parameters. The installed templates embody a tiny subset of the wide variety of heat transfer problems that SYMMIC can analyze.
    Does the software contain a library of commercial parts?
    Are custom templates available?
    Yes. CapeSym engineers can build templates for any process to provide custom, parameterized thermal models that can be used over a large domain of MMIC, package, and board designs. Please Contact Us for more information.
    Can users alter templates or create new ones?
    Yes. The template formats are completely open and existing templates can be easily modified using a plain text editor. The software also includes tools to aid in the modification and validation of templates.
    Can SYMMIC import my geometry?
    As a general rule, no. Three-dimensional geometry cannot be created in another tool, such as SolidWorks, and then imported as a device template into SYMMIC.
    Can SYMMIC import GDSII artwork??
    A companion application called GDS2SYMMIC was provided that can be used to import GDSII artwork and create a device template from it. The difficulty with GDS2SYMMIC was that the user has to input all of the process information to convert the artwork to a real 3D model. With device templates, all of the process information is already built in. Furthermore, some aspects of the thermal model, such as the locus of heat generation in the channel, or even the dimensions of the gate metal, will not be defined in the artwork. Hence, the GDS2SYMMIC utility is no longer maintained and will not be available in future releases.
    How is the locus of heat generation defined?
    In most of the generic templates the locus of heat generation in the active region of the device is designed to reproduce published data for a particular class of devices. The locus is usually parameterized to allow the user to modify the distribution laterally within the channel for different operating conditions. Different types of loci, such 2D sheets at the interface between epi-layers or volumetric power dissipation in a given epi-layer, can be constructed. There are several examples available within the set of publicly available templates.
    How can the total power be viewed?
    The total power flux dissipated in a device or layout can be viewed by using the Model Check dialog.
    What types of geometry can be modeled?
    SYMMIC models rectilinear geometry in which the sides of features are aligned with the x- and y-axes, and the stackup is composed of layers with top and bottom faces parallel to the z-axis. This arrangement of features is sufficient for most thermal modeling and allows hexahedral brick meshes to be generated and solved very reliably.
    What if my device has a circular via?
    It is not possible to define circular features in the current version of SYMMIC, but it is possible to investigate the temperature effect of a circular via of a certain diameter. Two different simulations with square vias can find the range of temperature effects. Use one square via sized to inscribe the circular via, and another sized to circumscribe the circular via.
    Is there a way to share vias between FETs?
    Yes. Please download the generic Array FET templates for some examples.
    How can I get rid of a via?
    To get rid of a via you remove its thermal effects by filling it in with the substrate, i.e. changing its component materials to the substrate material.
    How can I get rid of a component?
    One way to get rid of a component is to simply remove its thermal effects by changing its material to air. Another way is to use the Device Template Editor to delete it.
    Can a device have multiple boundary conditions?
    Yes. For example, a temperature file be used for the backside boundary condition with a film boundary condition on the topside. Within a single device template any combination of boundary conditions can be solved. However, if the device is used in a layout, then solving the layout through superposition may come with caveats. See the discussion on valid layouts in the Users Manual for more information.
    What does it mean to solve a layout by superposition?
    A set of solutions is obtained, each with a single device powered on and all other devices off. These solutions are added together to generate the final solution. This approach reduces memory requirements since the full mesh including details of all devices does not have to be directly solved.
    How can superposition be applied to a nonlinear problem?
    An extra iteration is performed to adjust for the effects that temperature-dependent thermal conductivities have on thermal coupling between adjacent devices.
    Can I solve a layout without using superposition?
    Yes. By using the "Export" operation the layout can be converted to a device template in which a single mesh for the whole layout can be solved directly.
    How does the Export operation work?
    Export converts a layout to a device template using either of two modes of operation: one simplifies the model and the other keeps all the details. The first mode is designed to coarsen the mesh to get a more efficient simulation of the bigger structure. In doing this, export eliminates the details of the device and replaces them with a surface flux of equal value. The accuracy of the device simulation is thrown away, but from the stand point of the boundary conditions on the bottom of the layout, this does not matter. After solution of the exported layout, these boundary conditions can be brought back into the original layout for the final analysis. In the second mode of operation, a more complex device is created that can be solved directly for detailed temperatures in all devices, provided sufficient memory is available to carry out the calculation. Modes of operation intermediate between these two extremes can be realized by setting export flags on individual components within the template(s).
    Is thermal analysis of a flip-chip possible?
    Yes. For an example please see the application note:

    Flip Chip Solution using Export


    Usage Questions?
    For answers to questions about using the software, consult the extensive Users Manual, available online and also accessible from the Help menu of the application.

    You may access the manual from a google search to quickly find specific information. For example, try this search for examples of amplifier thermal simulations.

    Individual help (.chm) files are provided for most of the device template examples. If you are having trouble viewing downloaded .chm help files, the operating system may be blocking the content. Please see this external page for possible solutions.