material precision processing “lancet” – high power uv laser
guide
with continuous development of laser technology, laser processing has been fully applied to the production of various industries.
laser processing theory:
the beam emitted by the laser is focused with high energy after passing through the lens system, then processing on the material by photo-thermal effect.
according to different absorption capacity of the materials, normally lasers in the market can be divided into two kinds：ir laser and uv laser. the contrast is as follows:
|
laser |
ir laser |
uv laser |
|
wavelength (nm) |
1064 |
355 |
|
single photon energy |
small |
big |
|
focus spot |
big |
small |
|
processing material |
only part of the materials can absorb ir light, small processing range |
most materials can absorb uv light, wide processing range |
|
processing theory |
heat the surface of the material and cause physical reaction ( vaporization, evaporation) to achieve removal of affected material. |
high energy uv light directly destroys the molecular on material surface and achieve removal effect, resulting in small heat affected zone |
|
heat affected area |
|
 |
with comparison above, it is obviously known that:
compared with ir laser, uv laser has short wavelength, small focus spot, high energy of single photon, small thermal-affected zone, and most materials have higher absorption rate for uv light, and can process many materials that cannot be processed by ir light.
355nm laser is developed and obtained by nonlinear effect with frequency conversion technology of crystal material. its working theory is shown below in figure 1.
figure 1.
activating medium nd: yag or nd: yvo4 1064nm ir laser is generated by external excitation source. ir pulse laser is generated by q technology of sound and light modulation, then by frequency doubling crystal, the 532nm green light is generated. the remaining ir laser and green laser are finally generated by sum frequency crystal.
at present, due to continuous improvement of laser processing efficiency and requirements from industrial applications, nano laser above 10w becomes popular in the market, so medium high power rate nano laser with high power rate, narrow pulse width, high repetition frequency is the main research direction for various companies.
at present, there are several companies that can provide uv laser above 10w in china, however its stability is far from that of imported lasers. how to ensure high power uv laser output and in the meantime ensure its stability has also been a difficulty faced by domestic companies.
through introduction of advanced foreign uv laser production technology and combined with its over 10 years of uv laser research and development experience, in the beginning of 2018, bellin laser promoted its new generation of high power rate uv integrated machine —— marble uv. (marble uv output rate is 10—15w、pulse width < 25ns、m…^ 2 < 1.3)。marble uv figure 2：
figure 2
marble uv advantages:
marble uv by adopting advanced design of resonant cavity and laser control technology, achieves excellent beam quality and narrow laser pulse width at high power rate operation. special cavity compensation technology and harmonic conversion technology have achieved high efficiency and stable frequency doubling conversion. compared with traditional nano uv laser, marble uv adopts integrated design construction in which integrated all control circuits and optical devices in laser head which makes the laser machine more compact. in this way, customers can control the laser head by software. without the control box, it is more convenient for customers to integrate device system.
applications
high power laser is mainly adopted by fine processing for hi-tech market including fpcb, pcb drilling, ceramic drilling and scribing, glass or sapphire cutting, wafer line cutting on led base, special glass cutting, laser marking. related applications as follow:
01、fpcb /pcb drilling and cutting
the matrix material of fpcb is some special polymer (such as polyimide). it will cause deformation at the edge of processing area if heated, resulting in serious carbonization. since the processing of uv laser is “cold processing”, the uv light directly destroys its molecular on material surface, so that the molecular is separated from the main object, in this way the heat affected zone becomes smaller. the edges in figure 3、4 are obviously smooth.
figure 3 figure 4
02、wafer line cutting
wafer is silicon wafer used in silicon semiconductor integrated circuits, its original material is silicon. high power uv laser has great advantages in wafer line cutting. in figure 5、6, the uv laser has short wavelength, strong focus spot, while processing, it can obtain a small incision and shallow scribing depth line which can produce less residue.
figure 5 figure 6
03、laser marking
laser marking is one of the most important application in laser processing. the principle of laser marking is that the material is locally irradiated with high energy density laser to vaporize the surface material or make color change by chemical reaction, thus leaving a permanent mark. since most materials have good absorption to uv light, thus it can be applied to most materials for surface fine marking and can be used to produce various patterns, characters and symbols. at the same time, the marking efficiency is relatively high and easy to identify. shown in figure 7、8.
figure 7 figure8
with continuous improvement of uv laser core technology and continuous expansion of laser processing application fields, high power uv laser will certainly make great brilliance in processing fields.
hereon, bellin laser will continue to advance in the development of high power uv laser, helping to expand applications of lasers!
