Why Use Ceramics As A Printed Circuit Board - Ceramic PCB Manufacture Process Introduction

Why use ceramics for circuit boards?



Ceramic PCB



Ceramic circuit boards are actually made of electronic ceramics material and can be made into various shapes. Among them, the ceramic circuit board has the most outstanding characteristics of high temperature resistance and high electrical insulation performance, and has the advantages of low dielectric constant and dielectric loss, high thermal conductivity, good chemical stability, and similar thermal expansion coefficient of the component, and Ceramic printed circuit boards are produced using LAM technology, a laser rapid activation metallization technology. Used in LED field, high power semiconductor module, semiconductor cooler, electronic heater, power control circuit, power mixing circuit, intelligent power component, high frequency switching power supply, solid state relay, automotive electronics, communication, aerospace and military electronics Component.




Unlike traditional FR-4 (glass fiber), ceramic materials have good high-frequency performance and electrical properties, and have high thermal conductivity, chemical stability and thermal stability. The ideal packaging material for a generation of large-scale integrated circuits and power electronics modules.


Main advantages:


1. Higher thermal conductivity


2. More matching coefficient of thermal expansion


3. A harder, lower resistance metal film aluminum oxide ceramic circuit board


4. The solderability of the substrate is good and the use temperature is high.


5. Good insulation


6. Low frequency loss


7. be assembled in high density


8. Free of organic constituent, resistant to cosmic rays, high reliability in aerospace and long service life


9. The copper layer does not contain an oxide layer and can be used for a long time in a reducing atmosphere.


Technical advantages



Technical Advantages of Ceramic PCB



Ceramic printed circuit board technology manufacture process introduction - punching hole


With the development of high-power electronic products in the direction of miniaturization and high speed, traditional FR-4, aluminum substrate and other substrate materials are no longer suitable for the development of high-power and smart applications in the PCB industry, with the advancement of science and technology. Traditional LTCC and DBC technologies are gradually being replaced by DPC and LAM technologies. The laser technology represented by LAM technology is more in line with the high-density interconnection of printed circuit boards and the development of fineness. Laser drilling is the front-end and mainstream drilling technology of the PCB industry. This technology is efficient, fast and accurate, and has great application value. The RayMing ceramic circuit board is made by laser rapid activation metallization technology. The bonding strength between the metal layer and the ceramic is high, the electrical performance is good, and the welding can be repeated. The thickness of the metal layer can be adjusted within 1μm-1mm, and the L/S resolution can be achieved. 20μm, which can directly realize via connection, providing customers with customized solutions.



Ceramic Printed Circuit Board Technology Manufacture Processes



The laterally excited atmospheric CO2 laser was developed by a Canadian company and has an output power as high as one hundred to one thousand times compared to a conventional laser, and is easy to manufacture. In the electromagnetic spectrum, the radio frequency is in the frequency range of 105-109Hz, and the frequency emission CO2 is developed along with the development of military and aerospace technology. The medium and small power RF CO2 laser has excellent modulation performance, stable power and high operational reliability. Long life and other characteristics. UV solid YAG is widely used in plastics and metals in the microelectronics industry. Although the process of CO2 laser drilling is more complicated, the production of micropore aperture is better than that of UV solid YAG, but CO2 laser has the advantages of high efficiency and high speed in punching, and the market share of PCB laser micropore processing can account for 80%.


The domestic laser microporous manufacture is still in the development stage, and there are not many enterprises that can be put into production. The short-pulse and high-peak power laser is used to drill holes on the PCB substrate to achieve high-density energy, material removal, and micro-hole formation. Ablation is divided into photothermal ablation and photochemical ablation. Photothermal ablation refers to the rapid absorption of high energy laser light by the substrate material to complete the pore forming process. Photochemical ablation refers to the combination of high photon energy in the ultraviolet region of more than 2 eV electron volts and laser wavelength in excess of 400 nm. The manufacture process can effectively destroy the long molecular chain of the organic material, forming smaller particles, and the particles can rapidly form micropores under the external force.



The Process of CO2 Laser Drilling for Ceramic PCB



Today, China's laser drilling technology has a certain amount of experience and technological progress. Compared with the traditional punching technology, the laser drilling technology has high precision, high speed, high efficiency, large-scale batch punching, suitable for most hard and soft materials, no loss to tools, and waste generated. The advantages of less material, environmental protection and no pollution.


The ceramic circuit board through the laser drilling process has the advantages of high bonding force between ceramic and metal, no falling off, foaming, etc., and the effect of growing together, high surface flatness, roughness ratio of 0.1 μm to 0.3 μm, laser hitting The hole diameter is from 0.15 mm to 0.5 mm, and even 0.06 mm.


Ceramic circuit board manufacture- etching


On the copper foil to be retained on the outer layer of the circuit board, that is, the circuit pattern is pre-plated with a layer of lead-tin resist, and then the copper of the unprotected non-conductor portion is chemically etched away to form a circuit.


According to different process methods, etching is divided into inner layer etching and outer layer etching, inner layer etching is acid etching, wet film or dry film is used as resist; outer layer etching is alkaline etching, and tin-lead is used as resist.


Basic principle of etching reaction


1. Acidic cupric chlorideetching



Acidic cupric chloride etching for Ceramic PCB

Acidic cupric chloride etching



Development: The portion of the dry film that is not irradiated with ultraviolet light is dissolved by the weak alkalinity of sodium carbonate, and the irradiated portion remains.


Etching: According to a certain proportion of the solution, the copper surface exposed by dissolving the dry film or the wet film is dissolved and etched by the acidic copper chloride etching solution.


Fading film: The protective film on the line is dissolved according to a certain proportion of the potion at a specific temperature and speed.


Acidic cupric chloride etching has the characteristics of easy control of etching speed, high efficiency of copper etching, good quality, and easy recycling of etching liquid


2.  Alkaline etching



Alkaline Etching for Ceramic PCB

Alkaline etching



Fading film: The film is removed from the film surface by using meringue liquid to expose the unprocessed copper surface.


Etching: The unwanted underlying copper is etched away with the etchant to leave a thickened line. Among them, auxiliaries will be used. The accelerator is used to promote the oxidation reaction to prevent the precipitation of cuprous mis-ions; the repellent is used to reduce the side erosion; the suppressor is used to suppress the dispersion of ammonia, the precipitation of copper and accelerate the oxidation of copper.


New lotion: Use ammonia monohydrate without copper ions, and remove the residual liquid on the board with ammonium chloride solution.


Whole hole: This procedure is only applicable to the immersion gold process. The excess palladium ions in the non-plated through holes are mainly removed to prevent gold ions from sinking in the gold sinking process.


Tin-stripping: The tin-lead layer is removed using a nitric acid solution.


Four effects of etching


1.Pool effect


During the etching manufacture process, the liquid will form a water film on the plate due to gravity, which prevents the new liquid from coming into contact with the copper surface.



Four effects of Ceramic PCB Etching-Pool effect

Pool effect



2. Ditch effect


The adhesion of the drug solution causes the drug solution to adhere to the gap between the line and the line, which can result in different etching amounts in the dense area and the open area.



Four effects of Ceramic PCB Etching-Ditch effect

Ditch effect



3. Via effect


The liquid medicine flows down through the hole, which leads to an increase in the speed of renewing the liquid medicine around the plate hole during etching, and the etching amount is increased.



Four effects of Ceramic PCB Etching-Via effect

Via effect



4. Nozzle swing effect


The line parallel to the swing direction of the nozzle, because the liquid medicine between the lines is easily dissipated by the new liquid medicine, the liquid medicine is refreshed quickly, and the etching amount is large;


The line perpendicular to the direction in which the nozzle swings, because the liquid medicine between the lines is not easily dissipated by the new chemical liquid, the liquid medicine is refreshed at a slow rate, and the etching amount is small.



Four effects of Ceramic PCB Etching-Nozzle swing effec

Nozzle swing effect



 Common problems in etching manufacture and improvement methods


1. The film is endless


Because the concentration of the syrup is low; the speed of the line is too fast; problems such as nozzle clogging can cause the film to endlessly. Therefore, it is necessary to check the concentration of the syrup, and adjust the concentration of the syrup to an appropriate range; adjust the speed and parameters in time; and clear the nozzle.


2. Board Surface oxidation


Because the concentration of the syrup is too high, the temperature will be too high, which will lead to oxidation of the surface of the board. Therefore, it is necessary to adjust the concentration and temperature of the syrup in time.


3. Theetchcopper is not finished


Because the etching speed is too fast; the composition of the syrup is biased; the copper surface is contaminated; the nozzle is clogged; the temperature is low, and the copper is not finished. Therefore, it is necessary to adjust the etching transport speed; re-check the composition of the syrup; be careful of copper contamination; clean the nozzle to prevent clogging; adjust the temperature.


4. The etch copper is too high


Because the machine runs too slowly, the temperature is too high, etc., which can lead to excessive copper corrosion. Therefore, measures such as adjusting the machine speed and adjusting the temperature should be taken.