Substrate Stackup Definition in ADS (23)
In this section, we will learn about the Substrate Stackup Definition in ADS layout, which refers to the process of defining the materials and properties of each layer of the circuit board. This is crucial in RF and microwave circuit design because the material properties and stacking methods of different layers can significantly affect the performance of the circuit.
In the previous section, we built a circuit structure using microstrip lines. Stackup Definition is very important for additive manufacturing simulation, without which we will not be able to do anything.
We can select (Substrate Editor) in the toolbar , or select “EM – Substrate”, then we can find that there is currently no ADS substrate.
Click “OK”, then we need to set the file name of the substrate and its template:
In this experiment, we use the default name and select “25milAlumina” as the substrate template. We can see that ADS provides us with a variety of substrate templates:
- 25milAlumina: Alumina substrate with a thickness of 25 mils. Alumina is a material with high dielectric constant and low loss, suitable for high-frequency and microwave circuit design, and can provide good thermal conductivity and mechanical strength.
- 100umGaAs: A gallium arsenide substrate with a thickness of 100 micrometers (um). Gallium arsenide has high electron mobility and is suitable for high-frequency and high-speed electronic devices, such as radio frequency amplifiers and high-frequency oscillators.
- 50milStripline: A stripline structure with a thickness of 50 mils. Stripline is a transmission line structure commonly used in high-frequency circuits and microwave circuits, providing good signal integrity and transmission characteristics.
- 600umSilicon: A silicon substrate with a thickness of 600 microns. Silicon is a common semiconductor material and is widely used in integrated circuits and microelectronic devices.
- board_4layer: Four-layer circuit board. Multi-layer circuit board design suitable for complex circuit layout, providing additional signal layers and power/ground layers to improve signal integrity and power distribution.
- board_6layer: Six-layer PCB. More complex multi-layer PCB design, suitable for circuit designs that require more routing layers and higher performance.
- board_8layer: Eight-layer circuit board. Highly complex multi-layer circuit board design, providing higher routing density and better signal integrity, suitable for advanced electronic devices and systems.
- TwoLayerFR4: Two-layer FR4 circuit board. FR4 is a common printed circuit board (PCB) substrate with good mechanical and electrical properties. The two-layer design is suitable for simple circuit design and rapid prototyping.
Then click 
, we can modify the substrate structure according to our needs (directly click on the part in the substrate to modify it on the right side of the page).
Then we select “Technology – Material Definitions” and in the “Dielectrics” tab, we can add the required materials. We can add them manually or search in the ADS database.
Similarly, in the “Conductors” tab, we can also add conductors according to our needs:
Then click “OK”. Now select the electrolyte, we can see the material we just imported, select “Rogers_R04350”, and change the thickness to 20mil:
Similarly, we can modify the Conductor from PERFETC_CONDUCTOR to “Copper”, and select it as “Intrude into substrate” (the original sheet along the positive or negative Z-axis feels like a 2D material with no thickness), and then we set the thickness to 35 um:
After the modification is completed, we save our stack definition. If we want to add vias (for grounding or other operations), we can right-click on the dielectric layer and select “Map Conductor Via” to map the vias and set their properties on the right side of the window:
Finally save our design.
