What the heck is a probe card? Three minutes to explain!

Probe bench, everyone knows it. It is an important equipment used to test the electrical properties of semiconductor devices, the probe (card) is part of it, mainly used for CP test (wafer test or probe test Circuit Probing, Chip Probing, not the CPDD you think of that CP ......).

The position of CP test in the chip industry

CP test is very important for pre-screening chips to avoid unqualified Die being packaged and sold as products.

So what is a probe card?

Let's first introduce what is a probe table. Everyone knows the multimeter, right?probe test system It is the small instrument for measuring voltage and current in junior high school physics experiments. Probe table is essentially similar to the multimeter, also used to test the circuit with. Only, the probe table to be much more expensive, multimeter dozens of dollars can buy, but the probe table, the bottom of the hundreds of thousands of dollars, expensive ten million, hundreds of millions of dollars is not impossible.

But the size of the chip is too small, when testing, you can not take the multimeter to the chip to poke it, right? Even the tip of a needle multimeter, a poke through, the chip is estimated to be poked by you.

So there is a big smart combination of microscope and multimeter (plus precision displacement platform, air pump, etc.), so there is a probe stage, mainly used for micro-size integrated circuit testing. The Probe Table consists of six basic components:

Wafer chuck: a device used to hold a wafer or chip without damaging it.

Carrier Table: Used to hold the chuck in place and move it precisely in X, Y, Z and angle.

Air Pump: Used to maintain the horizontal stability of the probe stage.

Manipulator: used to position the probe on the DUT.

Probe (card): mounted on the robot arm for contact testing.

Microscope: Used to view and magnify the DUT and probe tip.

Probe "sticking" on the probe table

Probe table can be simply understood as a multimeter pen, used to "zap" in the specific nodes of the chip for electrical performance testing.

So what is a probe card?

Probe card = probe + electronic components + wire + PCB, is a kind of integrated test interface, mainly on the bare chip without packaging (Die) for testing (for the simple reason that, if packaged, can be soldered on the circuit for the test ah).

Probe cards can be very simple (only one probe) or very complex,RF probes with hundreds or even thousands of probes to meet the requirements of integrated circuits or simultaneous multi-point CP test.

Probe cards for CP test are customized devices, each product needs to be customized by the supplier according to the input information provided by the chip design company, they are not universal, so their shipments are not large.

Probe card classification

Probe cards are categorized into three main categories: MEMS probe cards, cantilevered probe cards, and vertical probe cards.

Probe card is the core CP test consumables, MEMS probe card has gradually become mainstream. Probe card is a semiconductor wafer testing in the chip under test and the interface between the test machine, is considered to be the test equipment "gold finger" (directly poked in the chip on the "gold" finger, the probe head is really gold yo).

Market conditions

The first two years affected by the epidemic, QYResearch research shows that in 2021 the global probe card market size of about 15.8 billion yuan (RMB), is expected to reach 24.7 billion yuan in 2028, the compound annual growth rate (CAGR) during the period of 2022-2028 is 6.5%. Major local up-and-coming companies in China include Qiangyi Semiconductor, Zefeng Semiconductor, and others.

Postscript

Probe card is the key to CP test, by performing CP test on the chip on the wafer (electrical performance test, in fact, is the electrical performance test. But you see I said in the whole text is CP test, does not seem very professional. To give you a suggestion,probe card learn more of this kind of black language, it will really appear to be very professional), you can sieve out the defective chips, and then go to do packaging. This not only reduces the cost of chip packaging, but also ensures the quality of the chip.