There are usually hundreds to thousands of chips linked together on a single wafer. There is a gap between them of 80um and 150um, which is called SawStreet. The process of separating each chip with independent electrical properties is called Dicing Saw. At present, mechanical diamond cutting is the main technology of the scribing process. In this cutting method, the Diamond Blade cuts the block portion of the wafer at a high speed of 30,000 to 40,000 revolutions per minute. At the same time, the table carrying the wafer moves in a straight line at a certain speed along the tangent of the Blade's point of contact with the wafer. The silicon chips generated by cutting the wafer are washed away by DI water.

Dicing saw is a slicing machine with strong grinding as the slicing mechanism and aerostatic motorized spindle as the executing element. The slicing area of the wafer is slicing at the speed of 30,000 to 60,000 per minute. Meanwhile, the table carrying the wafer moves in a straight line along the slicing tangential direction of the contact point between the blade and the wafer at a certain speed. Split each chip with its own electrical power.

At present, with the development of electronic products, the market has put forward higher requirements for semiconductor packaging technology. The requirements for smaller, lighter, lower power consumption and higher reliability change with each passing day, and the emerging technology makes the cutting object no longer single, leading to the cutting process more complex. In order to improve cutting quality and processing efficiency, it is necessary to thoroughly analyze the factors affecting cutting quality. 

1. Spindle

The main spindle of grinding wheel scribing machine adopts electric spindle supported by aerostatic pressure. There are two types of spindles in use now, namely DC spindles and AC spindles.

DC Spindles:

---Axial forced ventilation cooling or heat pipe cooling is used to improve the cooling effect.

----Below the basic speed is the range of constant torque, above the basic speed is the range of constant power.

---Mainly used transistor pulse width modulation speed regulation system.

AC Spindles

---Specially designed squirrel cage three-phase asynchronous motor.

---Similar to the DC spindle motor, below the basic speed is the constant torque region, above the basic speed is the constant power region. When the speed exceeds a certain value, the power-speed characteristic curve slopes downward.

---Vector control is widely used for speed control.

Due to the difference in structure caused by dc spindle speed control precision is high (through feedback compensation speed), spindle working vibration is small, cutting effect is better, but its torque is relatively small with power AC spindle, thick, hard glass, ceramics and key and material cutting, cutting force is insufficient. Its cutting field is mainly for silicon wafer, gallium arsenide, oxide wafer and so on. Ac spindle torque is large, vibration is large, mainly for LED substrate, raw ceramics, new electronic packaging and other hard, precision requirements are not high products processing.

2. Water Sources

There are two sources of water used by the scribing machine: spindle cooling water and cutting cooling water.

Spindle cooling water

The main function of cooling water for the spindle is to provide cooling protection for the spindle. When circulating in the spindle, deionized water must be used, otherwise it will cause blockage in the spindle. The temperature of cooling water should be kept at room temperature, and it is recommended to configure a thermostatic water tank, otherwise the knife marks will be offset in the cutting process. Air spindle is a key component, it is necessary to check the waterway of the spindle regularly (6 months) to prevent scale from blocking the pipeline, otherwise it will cause damage to the spindle motor.

Scribing cooling water

Deionized water is mainly used, and special accessories can be added according to product needs, such as increasing carbon dioxide gas, changing water resistance value, etc.

3. Bearing Table

Ceramic microporous suction disc

Advantages: uniform suction, suitable for absorbing thin and brittle products with film, does not hurt the piece, can reduce the phenomenon of back collapse, and form a better cutting effect. Disadvantages: the surface needs to be fully covered, otherwise the suction is insufficient, for small workpiece, the blue film waste is serious. In addition, the microhole is easy to plug, not suitable for dust more processing environment.

4. Dicing Blade

Each type of tool has the outer diameter size, thickness, abrasive size (sieve number), binder, concentration, cutting edge shape, etc. According to the installation method, it can be divided into hubless dicing blade and hub type diamond dicing blade.

Hubless dicing blade

Hubless dicing blade needs to use flange fixed, its advantage is that the tool exposure is large, can process thicker products, can continue to use through the replacement of flange, cost-effective. But after using this fixed way, the tool to achieve true round effect, need to sharpen the blade, and the tool and flange contact part will have a slight beat, the cutting effect is not good.

Wafer hub dicing saw blade

Hub dicing saw blade fixed by means of high temperature and high pressure on the special flange, when the factory can be confirmed as true circle, due to the integration of cutter body and the flange, can be processing a high grade product, but making way to determine the blade above quantity cannot too big, usually this kind of dicing blade to show the amount of 0.30 ~ 1.15 m m smaller or larger quantity need special custom. Hub dicing blade can not process thicker products, this aspect has limitations.

The basic principle of tool selection: that is, the harder the material is; the softer the material is, the harder the material is.

For example, the more hard and brittle material cutting tool selection, will appear when cutting back collapse, back crack phenomenon. According to the requirements of edge collapse and material properties, choose the appropriate knife body adhesion, material hardness, concentration, emery particle size, etc.

The wheel scribing machine can cut a lot of materials, and there are differences in the material scribing process with different properties. Every parameter can be related to the scribing quality and efficiency. Therefore, it is a very important step to analyze all aspects of factors before cutting and select accurate blade.

Any problems you encountered during dicing on your machine, you can contact us freely, we MORESUPERHARD will provide you suitable dicing solutions for your working condition and workpiece.

----EDITOR；Julia Zhang

---POST:Doris Hu