Glass Substrates for High-frequency Circuit Boards
Circuit board with reduced transmission loss at higher frequencies
What are High-frequency Circuit Boards?
The type of PCB which is used in applications involving high-frequency signal transmission between objects
High-frequency Signal
High-frequency：higher than 1 GHz
Bandwidth： less than 1m
Applications
5G
3.6～6GHz
28GHz
Mobile
Autonomous car
79GHz
IoT
Disadvantage
・Easily attenuated by transmission loss
What is transmission loss in HF？
Attenuation per unit-length of high frequency signals
-
Dielectric loss
The loss that occurs when an electromagnetic wave propagates through a dielectric substrate
-
Conductor loss
The losses of circuit resistance and skin effect*
In order to improve transmission loss, it is important to work on the material and the wiring structure
* The skin effect is that alternating current tends to avoid travel throughthe center of a solid conductor, limiting itself to conduction near the surface.
Comparison with Substrate Materials
Comparison with Substrate Materials
Because of its low thermal expansion, glass has superior dimensional stability and superior high frequency transmission characteristics.
| Ref.Sillicon | Glass | Ceramics | Organic | ||||
|---|---|---|---|---|---|---|---|
| Alkali-free | Quartz | Al2O3 | AlN | FR-4 | PTFE | ||
| Coefficient of thermal expansion ×10-6/K |
3.9 | 3-4 | 0.5 | 7 | 4-5 | 20 | 7 |
| Permittivity εr |
12 | 5-7 | 4 | <10 | 9 | 4.5 | 2.1 |
| Loss tangent tanδ |
- | 0.002 | <0.0005 | <0.0005 | 0.0005 | 0.005 | 0.0002 |
| Chemical resistance | - | ||||||
| Features | - | Excellent high frequency transmission characteristics |
Heat dissipation | Low cost | Excellent high frequency transmission characteristics |
||
■Good ■Average ■Poor
Reference values
Reference values
Comparison with Dielectric Loss of Substrate Materials
The dielectric loss of quartz
glass is about 1/6 of PTFE *
*on 79GHz Band
■ Simulation result on
micro-strip-line
■ Permittivity/Loss tangent
● PTFE
（2.6 / 0.0007）
● Alumina
（9.8 / 0.0002）
● Quartz
（3.78 / 0.0001）
Design Specs
Standard Design
| Size mm | 300 × 300 | ||
|---|---|---|---|
| Thickness (A) μm | 200-600 | ||
| Copper Thickness (B) μm | 5 | 10 | 20 |
| Line（C） μm |
10 | 10 | 10 |
| Space（D) μm |
20 | 25 | 50 |
Cross-section
Through-hole Filling
【Actual value】
Via’s Top Diameter (E) 30 μm／Glass Thickness (F) 200 μm
Through-glass via cross-section
Substrate Material
Alkali-free glass / Quartz glass / Borosilicate glass / Soda lime glass / Sapphire glass
These dimensions are for reference only. Please contact us with your exact specifications.
Plating Examples
Wire Plating
Plating into Through-holes
Cross section
Through-glass via cross-section
Application Examples
| Purpose | Applications | Fields |
|---|---|---|
| Conduct electricity | Glass interposer (TGV) | Semiconductors, Electronics, Electrical appliances,Telecommunications,Industrial equipment, Medical |
| High frequency substrate, Communication antenna |
Semiconductors, Electronics, Electrical appliances,Telecommunications,Industrial equipment, Medical |
Production Flow Chart
Ebinax has an integrated production system from material procurement to dicing glass substrate.
- Discussion / Order
-
- Material procurement
-
- Glass through-hole processing
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- Plating (electrode formation)
-
- Polishing/Dicing
-
- Delivery
※Please contact us with your request.
Ebinax’s process leads to lower management costs and shorter lead times.
