What are the characteristics of BT laminates? What is the BT laminate for circuit boards?

In the field of electronics industry, the PCB (Printed Circuit Board) is one of the essential core components. Its quality and performance have a direct impact on the stability and reliability of the entire electronic product. Among a wide variety of PCB materials, the BT (Bismaleimide - Triazine) board material for printed circuit boards is highly favored because of its outstanding performance and extensive application fields. In this article, we will provide a detailed introduction to the BT board materials offered by PCB MASTER and analyze their application fields, manufacturing difficulties, preparation processes, and cost analysis from a professional perspective.

I. Introduction to BT Board Materials

BT board materials are a type of high-performance composite material, with the main component being bismaleimide-triazine resin. This material is renowned for its excellent thermal stability, electrical insulation, and mechanical strength. Compared with the traditional FR4 material, BT board materials have lower dielectric constants and loss factors, enabling them to perform better in high-frequency and high-speed signal transmission applications.

II. Application Fields of BT Board Materials

1. Communication Equipment: With the development of 5G technology, the demand for high-speed and high-frequency signal transmission is increasing day by day. Thanks to its low dielectric constant and excellent electrical properties, BT board materials have become an ideal choice in communication equipment.

2. Aerospace: Aerospace equipment working in extreme environments requires outstanding heat resistance and mechanical strength. BT board materials can meet these stringent requirements and thus are widely used in satellites, airplanes and other equipment.

3. Automotive Electronics: Modern automobiles are equipped with a large number of electronic control systems, which put forward higher requirements for PCB materials. BT board materials can not only withstand high temperatures but also have good impact resistance, making them very suitable for use in automotive electronic systems.

4. Medical Devices: For precision medical equipment, reliability and safety are of crucial importance. BT board materials possess excellent chemical stability and are not prone to degradation reactions, ensuring the stable operation of medical devices for a long time.

III. Manufacturing Difficulties

Although the BT board materials for circuit boards have numerous advantages, their manufacturing process also faces quite a few challenges:

Material Proportioning and Mixing: The bismaleimide-triazine resin needs to be mixed with other fillers in specific proportions to ensure that the performance of the final product remains unchanged. This step requires high precision; otherwise, it will affect the consistency of the material.

Lamination Process: During the lamination process, it is necessary to strictly control the temperature and pressure to ensure full bonding between each layer while avoiding defects such as bubbles or voids.

Drilling and Electroplating: Due to the relatively high hardness of the BT material, burrs are prone to be generated during the drilling operation. Meanwhile, during the electroplating process, it is essential to ensure good adhesion between the copper foil and the substrate so as to improve the electrical conductivity.

Dimensional Stability Control: Given its relatively low coefficient of thermal expansion, how to maintain dimensional stability during the processing is a key and difficult problem. This requires advanced processing equipment and strict management of the technological process.

IV. Preparation Process Flow of PCB Made of BT Material

4.1 Material Preparation Stage

Firstly, it is necessary to select high-quality BT base materials. This step is crucial because the quality of the base materials directly affects the performance of the final product. During the selection process, the company will conduct strict inspections on the raw materials to ensure that they meet the specified standards.

4.2 Lamination Process

Lamination is the process of bonding multiple layers of base materials together by heating and applying pressure. During this process, it is essential to precisely control the temperature and pressure to ensure that each layer is fully bonded without generating bubbles or voids. This step is usually divided into three stages: pre-impregnation, pre-compression, and final curing.

· Pre-impregnation: Immerse the base materials into the resin solution so that they can fully absorb the resin.

· Pre-compression: Stack the impregnated base materials and apply initial pressure to make the multilayer board tightly bonded.

· Final curing: Through high-temperature treatment, make the resin fully cured so that each layer is firmly bonded into one piece.

4.3 Drilling Stage

Drilling is carried out to form via holes, which are used to connect the circuits between different layers. During this process, it is necessary to use a precision drilling machine and accurately locate the drilling positions according to the design drawings. Meanwhile, attention should also be paid to controlling the speed and pressure of the drill bit to avoid the occurrence of burrs or breakage.

4.4 Copper Foil Deposition and Pattern Transfer

Copper foil deposition is to uniformly deposit copper ions onto the inner walls and surfaces of the drilled holes by means of electroless copper plating. This step requires multiple procedures such as cleaning, activation, and reduction to ensure that the plating layer is uniform and has strong adhesion. Subsequently, the designed circuit patterns are transferred onto the surface of the copper foil through the photolithography method:

· Coating Resist: Coat a layer of photosensitive resist on the surface of the copper foil.

· Exposure and Development: Utilize a laser exposure machine to project the circuit patterns onto the resist and conduct development treatment to form a protective film.

· Etching to Remove Excess Copper Foil: Through chemical etching, remove the copper foil in the parts not covered by the protective film, and only retain the circuit pattern parts.

4.5 Electroplating and Solder Mask Coating

In order to enhance the electrical conductivity of the via holes and circuit pattern parts, electroplating treatment is required. During this process, through the electrolytic action, metal ions are deposited onto the specified parts, thereby improving the conduction ability. Meanwhile, in order to protect the circuits from the influence of the external environment, it is also necessary to coat a layer of solder mask:

Coating Solder Mask Ink: Uniformly spread the solder mask ink on the entire board surface.

Exposure and Development: Use ultraviolet irradiation to harden the non-protected areas and conduct development treatment to remove the hardened part of the ink, and only retain the solder mask on the areas that need to be protected.

V. Quality Control and Inspection

To ensure that each PCB leaving the factory meets the customer's required standards and complies with international certification regulations, the company has established a series of strict inspection mechanisms:

Visual Inspection (VI): High-definition video equipment is used to take all-round pictures of each finished product to ensure that there are no obvious defects such as scratches or oxidation spots.

Automated Optical Inspection (AOI): The computer-aided system is utilized to scan and compare whether the actual circuit routing structure is consistent with the design files, detecting tiny deviations.

X-ray Inspection (X-Ray Inspection): Perspective imaging analysis is carried out on key nodes such as internal hidden via holes, blind vias and buried vias to ensure that there are no problems such as virtual connections or open circuits.

Electrical Test: All key parameters such as impedance values, capacitance values and inductance values are inspected item by item to ensure that they are within the specified ranges.

These comprehensive and meticulous steps ensure that the PCBs leaving the factory not only meet the basic functional requirements but also achieve a highly reliable and stable working state!

VI. Cost Analysis

Although BT board materials have numerous advantages, their production costs are relatively high, which is mainly reflected in the following aspects:

Raw Material Cost: Bismaleimide-triazine resin is a kind of high-molecular compound. It is expensive and has limited supply channels, resulting in persistently high raw material procurement costs.

Complex Manufacturing Process: From raw material preparation to the final product leaving the factory, a large amount of human and material resources need to be invested in each link. Coupled with the high cost of purchasing precision instruments and equipment, the overall manufacturing cost has been greatly increased.

Scrap Rate Issue: Due to the characteristics of the BT material for PCB boards themselves, the processing difficulty is relatively high. A slight oversight will lead to an increase in the scrap rate. Therefore, enterprises need to additionally consider the waste disposal costs and the additional expenses brought about by re-production.

Although the manufacturing cost of BT board materials is relatively high, in the long run, the benefits brought by their superior performance far exceed the investment part. Therefore, many enterprises are still willing to choose this new type of PCB base material as one of the future development directions.

In conclusion, the BT board materials provided by PCB MASTER have become a hot favorite in the current market due to their excellent thermal stability, electrical insulation properties and wide range of application fields. Despite numerous difficulties in the manufacturing process, by continuously optimizing the manufacturing process and improving product quality, more and better solutions will be provided for our customers.

It is believed that with the progress of science and technology, BT materials will surely be more widely used in more industries and play a huge role in the future!

It is hoped that this article can help you better understand the relevant information about the BT board materials provided by PCB MASTER. If you have any questions, please feel free to consult us, and we will serve you wholeheartedly!