Hybrid Multilayer PCB

A Hybrid Multilayer PCB combines different laminates such as high-frequency PTFE and FR-4. This helps in overcoming the poor structural properties of these materials in some cases.

This enables the hybrid PCB to operate at an efficient transmission speed of 25 gigabits per second per channel or higher for customer hot-pluggable applications. Surface finishing including palladium may also be utilized to improve the wire bonding capability and contact durability.

High-Frequency Unreinforced Laminate

FR-4 is a popular PCB material due to its great electrical properties, low cost, and ability to withstand moisture and varying temperatures. However, at higher frequencies, it loses signal integrity if not combined with other materials designed to Hybrid Multilayer PCB maintain signal strength. MADPCB carries a selection of high-frequency laminates that are compatible with FR-4 and can be used in a hybrid construction to provide the performance needed for Radio Frequency and Microwave applications.

HFULA is a glass-weave unreinforced laminate with copper cladding that has been developed to maintain signal integrity in the high-frequency region. Its superior dielectric constant, loss tangent, and bond strength make it an ideal material for use in high-speed applications. Unlike FR-4, HFULA does not require the use of flame retardants and has low moisture absorption rates. This makes it more environmentally friendly than FR-4, and also easier to handle during fabrication.

In some embodiments, the internal layers 202 and 203 may be shaped and crosshatched to prevent a layer of unreinforced laminate from sticking to a ground plane during the lamination process. However, the shaping and crosshatching of these layers do not affect the performance of the hybrid multilayer PCB 100.

Super Fine Traces

High-quality PCBs are critical components for a variety of electronic communication technologies. In addition to offering superior electrical functions, they also have chemical stability that ensures their integrity in various environments. In fact, they can maintain stable operation even under extreme changes of frequency, humidity and temperature. The circuit board’s dielectric properties (Dk and Df) and characteristic impedance are also key factors to its reliability and performance.

For example, a hybrid multilayer PCB may feature a set of substrates that enable efficient transmission at a speed of up to 25 gigabits per second per channel for chip-on-flex or chip-on-board optics products. This may be achieved by constructing connecting elements with super fine geometries on the top and bottom sections of the circuit board. Such connecting elements may include super fine traces with a trace width of between 50 micrometers and 60 micrometers, copper-to-copper pitches of 100 to 110 micrometers, wire bond pads in a 60-micrometer scale, and BGAs that have pitch dimensions smaller than 0.4 millimeters.

One challenge encountered by designers of hybrid multilayer PCBs is the use of dissimilar materials. This can cause significant registration issues during the manufacturing process because the different materials have varying CTE values. However, balancing the circuit material layers with a similar CTE value can minimize warping caused by the differing CTE rates.

Micro Strip Transmission Lines

Using a combination of super fine traces, micro strip transmission lines and BGAs, the hybrid PCB can operate at a transmission speed of 25 gigabits per second (Gb/s) or higher. This provides the capability to transmit large amounts of data quickly from one circuit board component to another while reducing cross-talk and radiation.

As the name suggests, a microstrip transmission line consists of a copper strip conductor with a width W and thickness T routed over a ground plane with a wider than the signal trace diameter and separated by a dielectric with a height H. The characteristic impedance of the microstrip transmission line is proportional to its frequency and its length. The phase velocity is less than the speed of light, and the propagation delay is dependent on the material dielectric constant, loss tangent and the distance between two traces.

As a result, the microstrip has a number of advantages over waveguide technology including: it is simple to produce, operates across a wide bandwidth, and has a small weight and dimensions. As well as this, the sandwich configuration of the traces between the reference planes naturally shields them from electromagnetic interference and noise. The microstrip is also compatible with coplanar and stripline routing techniques. The latter enables wider and thinner traces to achieve the same impedance value, as well as providing more space for high-density circuitry.

BGAs

In a BGA (Ball Grid Array) component package, the pins are replaced by small spherical balls of solder. These are placed on pads on the bottom of the chip carrier and melted during reflow soldering to provide a strong mechanical and electrical connection with the printed circuit board, PCB.

In hybrid multilayer PCBs, the BGA packages are positioned on the surface layers rather than in the inner layers. For this reason, they require careful Hybrid Multilayer PCB Supplier layout and routing to ensure that signals enter and exit the BGAs reliably. This includes determining suitable exit routes that can be manufactured with high yields and that won’t incur rework after assembly.

The first task involves deciding how signals will enter and exit the BGAs. This may involve routing traces through several rows of pins and will also include consideration for signal frequency, which requires that the traces be spaced appropriately to prevent crosstalk. The second task is ensuring that the BGA pins are aligned correctly with their corresponding pads on the PCB. This can be accomplished by using a standard pick and place machine with 0.05mm accuracy and by placing the BGA module on the PCB at a low mounting speed to avoid squeezing out the paste.

A third task is to consider the thermal management of the components. This can involve incorporating thermal vias, heatsinks and other cooling features into the design. It’s also important to consider the impact of power density on the thermal behavior of the hybrid multilayer PCB.