Today I will write about the method of making ceramic substrate
s.Ceramics can only be made into powder,and its molding method is a bit like the baking technique that women are familiar with,because wheat is also a process from powder to molding.
Rolling into a film Rolling refers to a rolling rod,which can be imagined as a rolling pin,through which ceramic powder and binding liquid(flour and water)are repeatedly rolled and formed.
Dry molding,that is,mixing ceramic powder and dispersant binder and then adding it to the mold to form a ceramic body.Just like we make mung bean cake.
"Extrusion molding"refers to mixing ceramic powder and binder,extruding from the gap of the mold,and forming a ceramic body.Who knows how to use a piping mouth?
In the casting process,a slurry of ceramic powder is first produced,and then the slurry is placed on the base tape,and the green body is spread by the mutual movement of the doctor blade and the slurry.
This is a technique of spreading pancakes.
The process of casting is simple,and it is the main forming method of ceramic substrates at present.
After the substrate is formed,it is covered with copper.
The shape of the electrical connection is related to the design of the laser electrode,the placement position and the gold wire bonding area.
Where gold-tin soldering is required,it is prepared by plating a metal film.
The advantages and disadvantages of several common ceramic substrates.
beryllium oxide ceramics have very good properties,but are very toxic,so they are basically not used now.
Alumina is widely used,mainly because of its low cost but limited thermal conductivity.Aluminum nitride ceramics have the characteristics of low bending strength and are widely used in the field of laser packaging.
Flexural strength is the weak point of ceramics.
What is the pressure that the material can withstand when it is bent but does not break,because COC and other objects are attached to metal,PCB and other high-elastic plates,which have high bending strength and will also bend ceramics.
There are also ceramics,which are objects that are prone to cracks and cannot be broken as a whole.This fracture toughness is also an ability to consider ceramics.
The properties of aluminum nitride are very good,but the bending resistance and fracture toughness are better than silicon nitride.
This characteristic of silicon nitride supports its thick copper plating,and in a larger temperature range(the deformation caused by thermal expansion and contraction is more serious),the ceramic and metal-plated electrodes will not fall off after repeated cycles.
This kind of ceramics is widely used in aerospace technology(extremely wide temperature changes),bridges,automobiles and other places with strong vibration.