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Multilayer PCB lamination – the secret of multilayer boards

Lamination-of-multilayer-PCB---the-secret-of-multilayer-boards

The majority of electrical devices use printed circuit boards (PCBs).While connecting the electronic parts; they support the device mechanically and physically. PCBs are often made of non-substrate materials that have copper circuit layers layered on top of them. These layers can be one layer, two layers, or even fifty layers or more, giving customers a wide choice of PCBs to choose from.

A multilayer PCB is made up of three or more double-layered PCBs. To prevent any of the components from melting, these boards are then bonded together and stacked between the layers of insulation. The thickest multi-layer PCB ever built was 50 layers thick.

What is laminate used for?

What-is-laminate-used-forUsing laminate as a material, PCB manufacturers create printed circuit boards. An important factor in a PCB’s performance is the laminate. For instance, it influences
● Electrical properties.
● Conductivity of heat.
● Mechanical strength of the board.

What is multilayer PCB lamination?

A Multilayer PCB lamination includes at least three conductive layers, and electrical connections between these layers are made using through-hole vias, blind, or buried vias. With the advancement of technology in the electronics field, the need for sophisticated PCBs has skyrocketed. A few benefits of multilayer PCBs include:
● Small size
● Increased robustness
● High assembly density
● Low weight, etc.

How many layers does a PCB have?

How-many-layers-does-a-PCB-haveMost mainboards have between 4 and 8 layers, although it is possible to create PCBs with approximately 100 layers. Large supercomputers frequently include boards with multiple layers, but as it becomes more efficient to replace such machines with clusters of regular PCs, multilayer PCBs are becoming less common. With the multilayer PCB lamination, it’s frequently impossible to know how many there are, but if you check the board closely, you might be able to count them.

How many types of laminates are there?

The four recommended laminate types for multilayer PCB lamination are those described below.

● FR4:
Flame retardant is denoted by the letters FR, and the number “4” denotes woven glass-reinforced epoxy resin. This substance acts as an insulator for multilayer PCB lamination by separating adjacent copper planes.

These are a few characteristics of this substance:
o Wide range of operating temperature.
o Provides adequate mechanical qualities to ensure board structure integrity.
o Compared to other materials, it is less expensive.

● High Tg Epoxy:
This laminate is perfect for multilayer PCB lamination. By using this, the PCB will be more stable and more resistant to heat, moisture, chemicals, and other properties that might otherwise render the PCB ineffective.

Materials with high Tg have the following characteristics:
o High-temperature durability
o Long delamination durability.
How-many-types-of-laminates-are-there
● BT Epoxy:
This laminate is used to make lead-free PCBs. It is also utilized for multilayer PCB lamination and has excellent thermal, mechanical, and electrical qualities.

● Polyimide:
This laminate is utilized for multilayer PCB lamination as well as high-density, flexible, rigid-flex, and flexible boards. It is considered appropriate for advanced applications requiring good thermal, mechanical, and chemical qualities.

How thick is laminate?

Laminate stack-up is a composite of many layers with defined thicknesses. For instance, the thickness of the FR-4 PCB core ranges from 0.2 to 3.2 mm and the thickness of the copper foil is roughly 254 mm. Lamination will glue them together with prepregs, increasing the overall thickness of the dry film significantly.

What is sequential lamination?

In this process, a dielectric is inserted between a copper layer and a sub-composite that is already laminated. This method makes it possible to execute challenging jobs such as the drilling of buried and blind vias and the routing of traces on internal copper layers.

Challenges with PCB Sequential Lamination:
● Limitation on the number of cycles
● The equipment aspect ratio for drill holes
● Aligning the drill hole while using Gerber files
● PCB Price

What are the properties of laminate?

Following are the properties of laminate:
1.Mechanical Properties:
o Peel strength
o Delamination time.

2.Chemical Properties:
o Flame resistance
o Moisture absorption.

3.Electrical Properties:
o Insulating properties
o Electric strength.

4.Thermal Properties:
o Glass transition temperature
o Thermal conductivity.

How are PCBs laminated?

How-are-PCBs-laminatedFollowing are the steps for PCB lamination:
① Preparation:
The panels are first washed in this phase to remove the corroded copper surface, potential fingerprints, the dry film remains, carbonate, and the anti-foam leftovers from dry film stripping.

② Micro-etching:
It is the action of oxidizing copper foil that has already been acid-plated. It homogenizes the copper layer and exposes no pads or channels for electrical signals.

③ Black oxide treatment:
During the third step, problems such as delamination are eliminated to improve epoxy resin adherence.

④ Inner-layer stack-up:
In this step, prepregs and inner layers are placed correctly on the glue machine and glued together. Another step included in this process is that the inner layer and prepregs are connected by riveting. This treatment is used to improve epoxy resin adherence and eliminate problems such as delamination.

⑤ Stack up:
The copper foil is then sandwiched between a stainless-steel patch and a prepreg during this step. Stack-up is thus consistently fixed and includes all inner layers including copper plating.

⑥ Lamination:
Layers are moved onto a cold press, unmolded, and prepared with registration holes using an X-ray machine after being subjected to high pressures and temperatures.

⑦ Hole registration:
The final phase involves deburring, chamfering, and rounding the corners of holes with the aid of an X-ray equipment. This step is important because the film obscures the previously created holes and must be removed.

How to protect PCB during lamination process?

How-to-protect-PCB-during-lamination-processBelow are some of the steps that can be used for the protection of PCB during lamination:
● Lamination must be performed in a controlled environment.
● Make sure the prepregs are free from any moisture.
● Make use of meshed copper planes.
● Apply surface finishing

Conclusion

IBE specializes in circuit lamination and sequential lamination to assure long-term and cost-effective operation of electronic equipment. The best way to get answers to any questions you may have is to speak with the manufacturer directly. Please visit our website for additional details on the subject of multilayer PCB lamination.

IBE has worked with clients in the electronics, automotive, medical, military, satellite, and telecommunication industries and also offers PCBs with special requirements. So, without wasting any further time, contact us now!

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