A Comprehensive Guide to Chip Scale Package – CSP

Semiconductors are highly important components of electronic devices. However, to ensure the proper functioning of semiconductors, it is essential for every chip to stay protected from stresses and elements. Integrated Chip packaging plays a significant role in the electronics manufacturing industry. Chip Scale Package is also an IC package with a surface mountable feature.

The term ‘CSP’ indicates a single chip used for the electronics manufacturing industry. The chip size is highly important for designers. Based on the surface-mounted ICP standards, engineers can determine the size and avoid complications. CSPs are available in different versions. As small and portable electronics have become highly popular in the modern world, chip size is a crucial factor. However, the main goal is to minimize the mounting area.

Working Principle and Structure of CSP Bundle-

The chip-size bundle comes with an interposer, which is not open. But, it remains in a covered form. While dealing with CSP, manufacturers use epoxy resins. As epoxy has no conductive properties, it is capable of joining wires in the circuitry. Besides, the epoxy shape is a crucial factor, as it lets you reduce the CSP bundle size. After accomplishing the process, you can manage the solder ball size present near the interposer. 

CSP package should not be confused with the COB or Chip on Board. In the case of the CSP, the sensor chip bundle must be less than 1.2 times the chip area. Sensor manufacturers do it with a glass layer that covers the chip. On the other hand, COB represents the sensing unit chip directly bonded to the PCB. The process of manufacturing camera modules involves using the COB.

CSPs provide several advantages, such as

• Smaller size due to the reduced thickness and footprint 
• Minimal weight
• Easy to assemble 
• Reduced production costs
• Better electrical performance

CSPs can endure alteration to the die size because a small die size can be accommodated easily by the interposer.

With chip scale packaging, you can leverage benefits from different packaging technologies. It is developed with a lead frame that helps with the assembly of different packages. So, it ensures the optimized use of the available interposer area. Engineers can use the same substrate for making several devices. The considerable reduction in weight and size provided by the chip scale package makes it perfect for use in laptops, phones, and other devices.

Chip Scale Packaging- Features and Advantages

With the chip scale package, you can find several advantages of using CSP technology. The most significant advantage is that the package size is small. The package has a BGA design, which increases the interconnect count to reduce the overall size.

What’s more, CSP is known for some special characteristics. They have no bent leads and satisfy you with self-alignment properties. So, the production cost will become low. CSP is different from other packages because it uses SMT or surface mountable technology. Manufacturers find it easy to start the manufacturing process. CSP also endures variations in the die size since the interposer design adapts to the decreased die size.

The bare die assembly is advantageous because of its performance and size. Besides, encapsulated electronic devices. Manufacturers use lead frames for building them and deal with the mass assembly of different packages. It increases the application of the interposer area.

Another big reason for using CSP is that interconnections get solidified. If you have successfully reduced the size, it will then lower the weight of the overall setup. 

So, CSP is a good technology that helps you with quick and easy package assembly. Manufacturers are able to control their manufacturing budget. The combination of surface mountable technology and CSP will improve the ease of producing bulk packages. Engineers can rely on different forms of dies during the emergency. Furthermore, the interposer will help them reduce the size without affecting the CSP.

Different Types of CSPs-

CSP packages are of various categories-

Flip-chip CSP-

The term ‘flip-chip’ refers to the chip that remains upside down. It is attached to a lead frame or substrate. Flip-chip CSP is different from general CSP because it needs bumps (copper pillars and solder) for interconnection. So, there is no use for conventional wire bonding. You can distribute the I/O pads over the chip surface. Thus, the chip size will be smaller due to the better circuit paths.

Again, as there are no bond wires, there will be no signal inductance. In the case of flip-chip CSP, the chip scale capacity will be around 200 I/Os. Due to its small and low profile, it is a lightweight package. Manufacturers can over-mold them in different ways

• The use of epoxy molding compound
• Capillary Underfill

If you want better protection of your chip, flip-chip CSP is the right choice. The solder joint will also be more reliable compared to COB. Thus, there will be better thermal packages, and the overall cost will be reduced.

Non-flip-chip

Non-flip-chip is another type of CSP that has several use cases. While dealing with non-FC CSP, you have to choose the electrodes. Non-flip chips are also present on the P-type and light radiation layer. However, the P-type plays a role in the overall process. Its main function is to allow thermal sink around the substrate material (sapphire).

In case the substrate cannot turn out proper heat conductivity, it may affect the system. So, there will be a disruption of the chip’s efficiency. Electrodes are positive and are the biggest factors that make non-flip chips weaker.

Professionals know how to use the electrodes cautiously. As each electrode is very close to the other, it may result in short circuits.

Leaded CSP-

Chip-On-Lead is a special technology where crystal or die is placed on the lead frame’s leads (but not the paddle). One thing to be noted is that there is no tape in the leadframe to provide sustenance during wire bonding. So, it is different from the traditional leadframe. COL packages are not only affordable but also robust. They meet good performance standards and key quality.

Wire-bonded CSP–

Wire bonding is a way to develop interconnections between other ICs or semiconductors and silicon chips. Thin bonding wires made from aluminum or gold are used for these interconnections. They also enable you to connect different PCBs. However, gold is a better choice due to its corrosion resistance and ductility.

Wire bonding is, in fact, a highly flexible and affordable interconnection method for assembling various semiconductor packages. You can also use it if the frequency is more than 100 GHz. Aluminum wedges and gold balls are popular processes applied by manufacturers and engineers in the microelectronics industry.

Ball Grid Array-

 BGA, or Ball Grid Array, is one of the chip carriers for ICs. The surface mount package is best for mounting devices (like microprocessors) permanently.

 Besides, BGAs are better than flat packs because they provide you with a lot of interconnect pins. Engineers can use not only the underside but also the perimeter of the device. The traces connect the leads of the Ball Grid Array to the wires. They can also establish a link between the balls to die. Higher speed and better performance are advantages of BGA.

So, these are all about chip scale packaging used by electronics engineers. You can consult experts to learn more about CSPs.