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CapStrate® Bulk Capacitance Embedded in a High-k Ceramic Substrate

Design Guide

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CapStrate Design Guide
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Choosing the correct CapStrate® influences the mechanical and electrical function of a design. Johanson Dielectrics offers ceramic substrates for use in application specific environments. It is recommended to choose the right substrate that meets the required electrical requirements and is suitable for the environment the product will operate in.

Johanson Dielectrics offers a variety of materials with a high dielectric constant (K) that can be used within CapStrate® designs. The dielectric constant is directly related to the amount of bulk capacitance that can be realized and allows for compact form factors.

Table 1: Available CapStrate® & Electrical Properties

CapStrate® Material X7R NP0 X8R
Dissipation Factor <2.5% <0.15% <2.5%
Dielectric Strength (V/mil) 200 300 200
Temperature Coefficient ±15% 0 ± 30 ppm/°C ±15%
Temperature Range -55 °C to +125 °C -55 °C to +125 °C -55 °C to +150 °C

CapStrate® Sizes & Shapes

Table 2: Rectangular Dimensions (CapStrate®)

Dimension Minimum Maximum Tolerance
Thickness 0.050” (1.27mm) 0.215” (5.461mm) +/- 0.005 (0.127mm)
Length 0.20” (5.08mm) 2.00”/1.00” (50.8/25.4mm) +/- 0.005 (0.127mm)
Width 0.20” (5.08mm) 1.00”/2.00” (25.4/50.8mm) +/- 0.005 (0.127mm)
Temperature Range -55 °C to +125 °C -55 °C to +125 °C -55 °C to +150 °C

Table 3: Circular Dimensions (CapStrate®)

Dimension Minimum Maximum Tolerance
Thickness 0.050” (1.27mm) 0.215” (5.46mm) +/- 0.005 (0.127mm)
Diameter 0.20” (5.08mm) 2.00” (50.8mm) +/- 0.005 (0.127mm)

The advantages of CapStrate® Dielectrics can be fully realized by replacing discrete capacitors with bulk capacitance from the ceramic substrates. The amount of capacitance that can be utilized varies depending on the design dimensions.

Tables 4 and 5 reference the maximum amount of capacitance that can be designed for dimensional, substrate and voltage constraints.

Typical voltage ratings vary from 100 to 1000V, however, engineers are invited to discuss special voltage requirements not listed below.

Table 4: Rectangular Bulk Capacitance (CapStrate®)

NP0 Length Width Thickness 100V 250V 500V 1000V
Maximum Size 2.00” (50.8mm) 1.00” (25.4mm) 0.150” (3.81mm) 5000nF 2500nF 1400nF 940nF
Minimum Size 0.20” (5.08mm) 0.20” (5.08mm) 0.050” (1.27mm) 30nF 9nF 5nF 2.8nF

X7R Length Width Thickness 100V 250V 500V 1000V
Maximum Size 2.00” (50.8mm) 1.00” (25.4mm) 0.150” (3.81mm) 120000nF 60000nF 25000nF 8000nF
Minimum Size 0.20” (5.08mm) 0.20” (5.08mm) 0.050” (1.27mm) 800nF 200nF 70nF 20nF

X8R Length Width Thickness 100V 250V 500V 1000V
Maximum Size 2.00” (50.8mm) 1.00” (25.4mm) 0.150” (3.81mm) 84000nF 42000nF 17500nF 5600nF
Minimum Size 0.20” (5.08mm) 0.20” (5.08mm) 0.050” (1.27mm) 560nF 140nF 49nF 14nF

  • Custom Geometry
  • Increased Bulk Capacitance
  • High Voltage Capabilities
  • Reduction in Size

Table 5: Circular Bulk Capacitance (CapStrate®)

NP0 Diameter Thickness 100V 250V 500V 1000V 10000V
Maximum Size 2.00” (50.8mm) 0.150” (3.81mm) 7600nF 3800nF 2600nF 1400nF 940nF
Minimum Size 0.20” (5.08mm) 0.050” (1.27mm) 25nF 6nF 3nF 1.7nF 2.8nF

X7R Diameter Thickness 100V 250V 500V 1000V 10000V
Maximum Size 2.00” (50.8mm) 0.150” (3.81mm) 180000nF 95000nF 40000nF 12000nF 8000nF
Minimum Size 0.20” (5.08mm) 0.050” (1.27mm) 550nF 140nF 45nF 15nF 20nF

X8R Diameter Thickness 100V 250V 500V 1000V 10000V
Maximum Size 2.00” (50.8mm) 0.150” (3.81mm) 126000nF 66500nF 28000nF 8400nF 5600nF
Minimum Size 0.20” (5.08mm) 0.050” (1.27mm) 385nF 98nF 31.5nF 10.5nF 14nF

Additional sizes and form factors not listed are possible. Contact Johanson to assess the feasibility of your design. Reference table 6 for the maximum capacitance density that can be used for a given substrate. Capacitance density, below, is presented in nF/(mils)3. This is the maximum amount of capacitance available in a given volume.

Table 6: Max Capacitance Density

Rectangular X7R NP0 X8R Circular X7R NP0 X8R
100V 4.00E-04 1.67E-05 2.80E-04 100V 3.82E-04 1.61E-02 1.13E-02
250V 2.00E-04 8.33E-06 1.40E-04 250V 2.02E-04 8.10E-03 5.67E-03
500V 8.33E-05 4.67E-06 5.83E-05 500V 8.49E-05 5.51E-03 3.86E-03
1000V 2.67E-05 3.13E-06 1.87E-05 1000V 2.54E-05 2.97E-03 2.08E-03

Johanson Dielectrics offers a variety of metallization schemes that are high reliability conductors. These metals can be utilized as conductors, solder pads, or methods of thermal transfer. Designers should select the available metal based on the metallization properties that best suit their design. Careful selection of particular metallizations is dependent on requirements for solderability, temperature resistance, and electrical performance.

Table 7: Metallization Schemes Available

Dielectric Ag / Pt Ni / Au Ag / Ni / Au
X7R X X -
X8R X X -
NP0 X - X

Table 8: Metallization Properties

Material Property Ag / Pt Ni / Au Ag / Ni / Au
Recommended Thickness 14µm 7-12µ” Contact Factory
Max Solder Temp 218°C 260°C 230°C

Table 9: Solder Pad Dimensions

Metallization Length (Minimum) Width (Minimum) Pad Spacing (Minimum)
Ag/Pt 0.015" (0.381mm) 0.010" (0.254mm) 0.007" (0.178mm)
Ni/Au 0.015" (0.381mm) 0.010" (0.254mm) 0.007" (0.178mm)
Ag/Ni/Au 0.015" (0.381mm) 0.010" (0.254mm) 0.007" (0.178mm)

Table 10: Standard Conductor Traces & Tolerances

Metallization Line Width / Space (Min) Line Width / Space Tolerance (Max) Trace / Metal Thickness
Ag/Pt 0.007” (0.178mm) 0.003”-0.005” (0.076-0.127mm) 0.014” (0.356mm)
Ni/Au 0.007” (0.178mm) 0.003”-0.005” (0.076-0.127mm) 0.014” (0.356mm)
Ag/Ni/Au Ag/Ni/Au 0.003”-0.005” (0.076-0.127mm) 0.014” (0.356mm)

Vias are used to connect different layers in the CapStrate® as a means of an electrical or thermal connection. Johanson Dielectrics offers plated through-hole vias for designers to use

Table 11: Via Mechanical Dimensions

Via Style Hole Diameter (Minimum) Hole to Hole (Minimum Spacing) Via to Edge (Minimum Spacing)
Plated Through-hole 0.028” (0.771mm) 0.012” (0.305mm) 0.015” (0.381mm)

We encourage all designers to submit their drawings or ideas for quick and easy feedback.

To submit:

  • Follow Johanson’s design guidelines and standard specifications
  • Provide CAD data in multiple layers
  • Identify “A” side and “B” side for double-patterned circuits
  • Provide tolerances and annotation
  • List CapStrate® type, dimensions, and rated voltage
  • Specify metallizations, thickness and tolerances, pads
  • Specify conductor traces, type, spacing, and tolerances
  • List any environmental or electrical testing needed
  • Other inspection or acceptance criteria

Don't miss the opportunity to work with our outstanding design engineers.

Send us a message for more information. We look forward to assisting you with your unique design requirements.

Assembly Services

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Includes but is not limited to, soldering resistors, inductors, wires and transistors.

One-stop design, manufacturing, and assembly ensures customers receive completed product, without the hassle of developing an assembly stations.