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Importance of a Probe Card PCB in Semiconductor Wafer Test System

In general, probe cards can be seen as expendable and maintenance is required to guarantee their performance and effectiveness. The resistance may rise and obstruct accurate readings owing to overload and the buildup of debris out from the wafer’s binding substance on the probe’s tips or probe needles.

What Does a Probe Card Mean?

In essence, probe card can be described as a board or interface useful in performing wafer testing on the semiconductor wafer. Before being produced and transported, integrated circuits on the wafer are tested for electrical characteristics and performance via this connection to the Automatic Test Equipment.

In essence, probe card acts as a platform which enables mechanical and electrical contact between both the electronic test system and the device undergoing testing. Each Probe Card has these components:

  • The Printed circuit board
  • The Organic Substrate (Multilayer)

We also see that this Probe Card forms a component of a wafer test system up to this point, but it must be tested before being incorporated into the test system. It is required to fulfill the standard for high – performing power as well as signal transmission during electrical testing due to the device bandwidth as well as increasing power demands. The difficulties for such probe card testing are driven by these needs.

In order to match all the pads present on that device being tested with the probes, the probe cards were created. The user must provide the manufacturer of the probe card PCBs with the device layout’s mechanical drawings or the device’s sample in order to have a probe card made.

For simultaneous multi-site and integrated circuit testing requirements, probe cards could be simple only with one probe (a diode), or they can be sophisticated possibly reaching a thousand probes. Edge finger (maximum to 48 pins) as well as ribbon cable is typically utilized for the cable connection into that probe card (which can reach 160 pins).

How Does Probe Card Function?

Probe card Circuit Board

Take the production of semiconductors as an example to see how to simplify the process. There are various integrated circuits located during silicon manufacturing.

After, this wafer gets chopped, packaged, and then shipped. However, the functionality of the circuits must be verified before packaging is done. The probe card is used to help with the electrical test. To establish the electrical path in between the tester and the semiconductor wafer, this probe card is installed into a prober which is then connected onto the tester. This probe card subsequently connects with the IC chips’ pads on the wafer using its metallic needles or elements to transmit the electrical data and necessary test parameters.

Since the tester’s head must be attached to the pads or metal bumps present on that wafer so as to communicate that electrical data, the prober could be thought of as such. This prober is utilized in docking the probe card, lower it to the wafer, and then wait for the bumps or needles to connect before establishing the current flow between the connections. Scrubbing off the layer of oxide and connecting to the surface of the metal beneath requires movement of these probing needles when they establish contact with those metal bumps present on the wafer.

Advanced Probes Types

FULL PCB MANUFACTURING Quote

The range of probe cards available today when choosing the type of card to employ to test the wafers is evidence that probe technology has advanced significantly in recent years. Let’s examine the several categories of sophisticated probes:

Vertical Probe

These vertical probes are cards which are utilized to evaluate multi-die devices like those related to general-purpose microcomputers and logic. It is the perfect option for high frequency and small pad wafers since these needles come typically brief and placed vertically with relation to a substrate.

MEMS-SP

This kind of probe makes use of the benefits of the MEMS technology as well as enables very accurate and dependable testing of microprocessors and logic devices using this probe card. The most cutting-edge probe technology now on the market is known as MEMS, or Micro Electro Mechanical System. With just one touchdown, it has the ability to establish one connection onto the wafer.

U-Probe

Probe cards called the U-Probe can be described as the most effective when measuring memory devices. It can make contact with the wafer which is about 12 inches long with just one touch downwards or contact. It may be utilized anywhere, in whatsoever position on that semiconductor wafer, and produces another even scrub in order to produce the finest results.

Reasons Why the Probe Card PCB is Used

Probe card Board

Below are the common reasons why probe card PCBs are used. These include manipulator limits, layout of the device, as well as production. Now, let’s consider each of them in detail.

Manipulator Limits

A standard prober could only position 8 to 12 manual manipulators all around a platen opening without the need for the probe card. Additionally, each probe tip must be manually adjusted by the operator, which is a laborious process that takes a lot of practice and time.

Layout of the Device

Whenever the user needs to probe any device that has a high pin count (>12), the probe cards play an important role.

Production

Probing applications for production make heavy use of probe cards. Production applications could be as simple as a diode with one probe or as complex as integrated circuits with hundreds of probes.

Conclusion

This probe card can be electrically attached to the test instrument and docked mechanically to the prober. The main goal is to create an electrical connection between both the test equipment and the wafer’s circuits, allowing for validation as well as testing of these circuits prior to dicing and packaging. It is made up of a circuit board as well as different contact elements, which are typically made of metal but could also be made of other materials.

To assist reduce manufacturing costs and boost productivity, we design and produce a wide variety of probe cards with high performance.