Do a chip the most basic link is to design -> streaming chip -> packaging -> test
What kind of tests do the chips need to do?
Mainly divided into three categories: chip function test, performance test, reliability test, chip products to market three tests indispensable.
1. Function test to see if the chip is right
2 performance test to see if the chip is good
3 reliability test to see if the chip is firm
●Function test, it is the parameter index function that tests chip, the person says is to see the baby that you are conceived in October is mule is horse come out to walk
●Performance testing: Because there are numerous possible steps to introduce defects in the manufacturing process of a chip, even the same batch of wafers and packaged finished products have their own advantages and disadvantages, the chip needs to be screened. In other words, it is to pick the stone in the egg and throw away the stone chip.
●Reliability test, the chip passed the function and performance test, got a good chip, but the chip will be the most annoying in the winter static electricity damage, in the thunder and rain in the dog days can work normally, and the chip can be used for a month a year or ten years, etc., these should be evaluated by the reliability test.
So what tools do we have to implement these tests?
●Test method: Plate-level test wafer CP test packaged product FT test system-level SLT test reliability test, multiple strategies simultaneously.
●Board level testing is mainly used for functional testing. PCB board + chip is used to build a simulated chip working environment, and the interface of the chip is extracted to test the function of the chip, or to see whether the chip can work normally under various harsh environments. The equipment to be applied is mainly instruments, and the EVB evaluation board is mainly needed to be made.
●Wafer CP test, often used in the function test and performance test, understand the Chip function is normal, and the fault screen out Chip Wafer Chip CP Chip Probing as the name suggests is the Probe with a Probe to plunge into the chips on the Wafer, the of all kinds of signal input into the Chip, the Chip output response to a crawl and comparison and calculation, also have some special scenes will be used to configure adjust Chip Trim need to apply the equipment is mainly automatic test equipment (ATE + Prober Prober, instruments and meters, need to make the hardware is Probe CARDSProbe Card.
●FT finished product testing after encapsulation, often used with functional test performance test and reliability test, check whether the chip function is normal, and whether there are defects in the process of encapsulation, and help in the reliability test used to detect the chip after snow thunder fire can still work to application of the equipment is mainly automatic test equipment (ATE Handler mechanical arm + + instrument and meter, the need to make the hardware is to test plate Loadboard + test Socket Socket, etc.
●System level SLT test, often used in functional performance tests and reliability tests, often used to supplement the FT finished product testing, as its name implies is under the environment of a System test, is to put the chip in it function to test its working environment is good or bad, the disadvantage is that only cover part of the function, low coverage so generally is a supplement to the FT method need to apply the equipment is mainly mechanical arm Handler, the need to make a hardware System Board System Board + test Socket Socket.
●Reliability Test, mainly is for chip exerts a variety of harsh environment, such as electrostatic, ESD is to simulate the human body or simulated industrial body chip and instantaneous large voltage and aging HTOL High Temperature Operating Life, aging is Accelerated at High Temperature chip, and then estimate the chip Life and HAST Highly Accelerated Stress Test Test chip packaging wet resistance ability, products are under strict Temperature under TestTest under humidity and pressure to see if moisture penetrates into the package along the colloid or the interface between the colloid and the conductor holder and damages the chip.
Chip Test is by no means a simple eggs pick stone, is not only critical of rigid can, also need the whole process control and participation from chip Design, should consider how to Test, whether should add DFT Design for Test Design, whether can you through the Design function since the Test FuncBIST less dependence on peripheral circuit, and Test equipment in chip open authentication, eventually issue a Test vector, should be considered should be the validation of the Test Bench based on periodic Cycle baseIn the chip stream Tapout stage, the chip test scheme should be formulated. The program development of ATE test should be carried out simultaneously with the production of CP/FT hardware, so as to ensure that debugging can be started as soon as the chip is off the wafer production line and the chip development cycle can be greatly shortened.
Test finally stepped into the stage of mass production is even more important, how to supervision and control test yield, how to deal with customer complaint and PPM low, how to optimize the test process, test program efficiency, reduce test time, reduce the test cost and so on a chip of the cost of the test is not so in fact is the quality, efficiency and cost balance of art.