Hybrid PCB Stack-up Optimizes Signal Integrity and the PCB Cost
Today we're going to talk about hybrid PCB. We mainly refer to high
frequency material mixed with epoxy glass.
Let’s see the stack-up to get idea about hybrid structure.
Layer 1 to layer 2 is the core of RO4350B high frequency material
and layer 3 to layer 4 is the core of FR-4 epoxy glass. The 2 cores
are bonded by a sheet of adhesive (prepreg).
Types of hybrid PCB
The hybrid PCB can be a mixture of FR-4 and high frequency material
as abovementioned, another type is a mixture of high frequency
material with different dielectric constant (DK), for example
RT/duroid 5880 and RO4350B etc.
Why do we use hybrid PCB?
There're 3 main reasons that convince us to use this type of high
frequency multilayer PCB, i.e. cost, reliability improved and
electrical properties enhanced.
The cost of high frequency material is much higher than FR-4,
sometimes, when using hybrid of FR-4 and high frequency material
can solve the cost problem.
It causes reliability problems when the CTE value of the PCB
material used is relatively high, while some high frequency
materials have high CTE characteristics. When a low CTE FR-4
material is combined with a high CTE material to make a multilayer
board, the composite CTE is acceptable, thus enhancing reliability.
Most of the time, some lines of the mixed PCB board require very
high electrical performance, some do not require high, in this
case, the parts with low electrical performance requirements will
be used FR4, while the parts with high electrical performance
requirements will use more expensive high frequency materials. Some
using different DK of material to make mixed PCB, it is also to
improve electrical properties, such as in some applications of
combiners and filters, using different values of DK material.
Micro-section of a hybrid PCB
Why choose FR-4?
Mixture of FR-4 and high frequency materials is becoming more and
more common because FR-4 and the vast majority of high frequency
materials have little compatibility problems.
Lamination
To get a reliable lamination, we first choose PP sheet of high
frequency material and use the correct pressing cycle. The adhesive
layer of the same material is more favorable for the simpler
pressing cycle.
| Our PCB Capability |
| PCB Type: | Hybrid PCB, Mixed PCB |
| Mixed type: | RO4350B + FR4; |
| | RO4003C + FR4; |
| | F4B + FR4; |
| | RT/duroid5880 + FR4; |
| | RT/duroid5880 + RO4350B |
| Solder mask: | Green, Red, Blue, Black, Yellow |
| Layer count: | 4 Layer, 6 Layer, Multilayer |
| Copper weight: | 0.5oz (17 µm), 1oz (35µm), 2oz (70µm) |
| PCB thickness: | 1.0-5.0mm |
| PCB size: | ≤400mm X 500mm |
| Surface finish: | Bare copper, HASL, ENIG, Immersion tin, OSP |
| | |
