More concerned were be pressed for the high reliability hermetic packages which acting as a key component in microwave devices for defense and avionics industries,due to the electronic devices are developing towards miniaturization,lightweight,high-frequency working and high-efficient density,multifunctional and high reliability.As a key factor,using excellent and new electronic packages material are an effective prerequisite to ensure high reliability of microwave devices.Whereas the above reasons,the preparation of novel silicon-aluminum alloys packaging materials were urgent problems by numerous manufacturers in China.
On account of large primary silicon,low compact density and low reliabilty, through the conventionally preparation methods producing the Si/Al compound materials,such as gravity casting,semi-solid processing and powder metallurgy technology can no longer meet the military,aerospace requirements. After years’ substantial research and development,with the proprietary Rapid Solidification process,ZKZY Co.,Ltd successfully fabricated binary silicon-aluminum alloys which can achieve uniform and isostropic and high relative density.The Rapid Solidification technology is very suitable for the production of silicon-aluminum alloys.Moreover,the process can overcome series of problems existing in the traditional processing,and have been successfully applied in the domectic defense and avinoics.
The state-of-the-art alloys are recognized as new packaging materials which proven having a wide range of applications.In contrast to common processes,the controlled expansion Al-Si alloys are produced by rapid solidification process in ZKZY Co. Ltd, the alloys performances have greatly enhanced in the tensile strength,yield strength,enlongation,fracture toughness,fatigue strength with an average of 20%~50%.The process is basically mature and the Si/Al compound materials quality is more stable than other companies in China.Currently,users including high frequency type packages,avionics,radar,telecommunications and optical supporting systems applications.
Main characteristics of Si-Al housing materials(named AlSi alloy raw materials,Si content by the weight of 27%~80%):
1)Pre-select coefficient of thermal expansion(CTE) in the range of 7~17ppm/℃,so it can be tailored to all sizes and shapes for different applications.
2)High thermal conductivity;
3)Low density and lightweight;
4)Outstanding thermo-mechanical stability;
5)Uniform and isostropic microstructure,no porority and holes;
6)Primary silicon distribute well,no macro segregation,finely and equiaxed grains(average grain size is about 10μm), relative density could reach up to 100%;
7)Easy of machined(e.g.CNC/EDM),platability and weldability;
8) Higher specific stiffness eminently suitable for a wide range of applications;
9)Environmentally friendly,present no disposal problem;
10)Excellent electrical conductivity(Perfect EMI/RFI shielding performance).
|
Grade |
Content |
Density g/cm³ |
CTE ppm/℃ |
Thermal Conductivity W/m.K |
Tensile Strength MPa |
Yield Strength MPa |
Poisson's Ratio |
Elongation % |
Elastic Modulus |
|
GPa |
|||||||||
|
ZY-AlSi27 |
Al-27%Si |
2.6 |
17 |
175 |
170 |
130 |
0.29 |
3.8 |
91 |
|
ZY-AlSi42 |
Al-42%Si |
2.55 |
13.5 |
143 |
200 |
187 |
0.29 |
1 |
105 |
|
ZY-AlSi50 |
Al-50%Si |
2.5 |
11.5 |
140 |
220 |
210 |
0.28 |
<1 |
108 |
|
ZY-AlSi60 |
Si-40%Al |
2.46 |
9 |
125 |
181 |
181 |
0.27 |
<1 |
121 |
|
ZY-AlSi70 |
Si-30%Al |
2.43 |
7.5 |
120 |
138 |
138 |
0.25 |
<1 |
131 |
Currently,some of companies has successfully produced the silicon-aluminum alloys in China,while the silicon content maximum only reach up to 50% by obsolete spray forming process. There is a serious of problems observed through the Si/Al alloy microstructure.The alloy microstructure has a great variation,it is obviously that the primary silicon exhibits coarse aricular eutectic phase and inconsistant microstructure which result in poor roughness and ductility.However,controlled expansion Al-Si alloys manufactured by rapid solidification technology in Wuxi ZKZY Advanced Materials Technology Co.,Ltd can obtain a refine microstructure with average grain size only about 10μm,and the alloys show no macro-segregation, uniform and homogeneous features,these key factors enhance the overall performance of materials.