1311_ Hardware design_ Summary of ICT concept, application, advantages and disadvantages

All learning summary ： GreyZhang/g_hardware_basic: You should learn some hardware design knowledge in case hardware engineer would ask you to prove your software is right when their hardware design is wrong! (github.com)

Listen to others at work ICT as well as FCT Too many times , In the process of listening to your discussion, I vaguely know that this is a method of checking product processing design in the production process , But there is still a lack of concept about what to do and how to do it . today , When I met an article on the Internet, I felt it had a good help for some of my previous doubts . such , Combined with some of my previous understandings and questions , Do a editing .

Before finishing , In fact, you can think about what knowledge points may be involved here ：1,ICT What is it? ？ 2,ICT What is it for ？ 3,ICT What is the general equipment , How to install and use ？ 4, ICT Is it a universal and available production technology link .

It needs to be noted that ：ICT Generally speaking, it is used to check new PCB Of , Find out the defects and correct them further . As for whether this amendment is also ICT The scope of , There is no clear explanation here . however , Words understood from the literal meaning itself , Since this is a test Then it should be a pure detection process .

This part , Some of my confused answers have begun to appear . First , Here it comes out ICT Abbreviation of , In-Circuit Test, I don't know if there is any special academic translation for general use , Literally it should be PCB Inspection of internal circuit . Also called needle bed internal circuit test , Maybe this name comes from the component elements of the equipment .

ICT Can check PCB Some short circuits 、 Open circuit and other faults . besides , You can also check the firmness of the chip through the suction cup , This is really something I didn't know before . I thought this process was completely electrical , Now it seems that there is still the possibility of mechanical operation .

Last , Here are some examples of solutions that may be relatively mature and well-known .

How does this process work ？ Generally speaking , The assembly plant will directly PCB Press in a probe “ The bed ”, Such devices are generally based on PCB Specially designed . after , The probe will pop out directly from the bottom and touch PCB Test on the circuit . Generally speaking , This process is highly automated , So it doesn't need too much manpower , At most, click the button to see the result .

Above are several ICT Brief introduction of the equipment . The first is the standard ICT equipment , This one is very enjoyable compared with the general introduction in the previous part . Basically, it is a direct probe test PCB Various parameters on . The second is MDA, It should be called manufacturing defect analyzer . This device has some software related settings , But this part can be used PCB Of CAD Data as input to automatically generate the corresponding test program . Using such data , It can probably generate 80% The program . The third kind is cable testing equipment , This test equipment is actually a special version MDA, Its special feature is that it can handle high pressure . Use high-voltage cables to do insulation tests . The second is “ Flying needle test ”, From the description of the content, it may be the probe driven by the manipulator and other motion execution parts to do the test . This kind of test fixture is simple and even does not need a fixture , Use software to control the probe movement to test . however , A big disadvantage is when the hardware design changes , The software also needs to be modified .

ICT The main components of the equipment ：ICT Tester 、 fixture 、 Software . among , The line tester has thousands of sensors or drivers , To realize signal measurement . And fixture , Not just a fixed part ,ICT In fact, the fixture has the function of wire harness , The sensor and driving parts are connected , And connected to PCB Up . And software , More refers to the processing software that processes and judges the collected results and gives the test results .

ICT What can be used to test , This need can be divided into two situations: no power supply and power supply .

When there is no power supply ：

A short circuit

Open the way

Lack of passive components

Lack of active simulator

Jumper

Absence of non electrical components （ This is similar to the firmness check of the previous chip , Non electrical inspection ）

When supplying power ：

Simulator device error

Digital device error

simulation 、 The installation direction of digital devices is wrong

Parameters such as capacitance and inductance are wrong

Transistor amplification factor

stuck process bus, I don't understand the concept

Diode inspection

Inspection of fuses and switches

the last one , I think there may be too much solder, waiting for inspection ？

As for what scene ICT It is a suitable application scenario , Generally speaking, we have to consider the cost . If the products involved, whether in quantity or in the future, may be maintained for a long time , Probably ICT Have to consider . Such links have been added , The quality of the products will certainly be more guaranteed . in addition , Compared with other test modes ICT There are also some , For example, you can test BGA、 Fast and efficient detection 、 Software is easy to do 、 It doesn't cost much 、 platform Universal 、 Large coverage, etc .

Actually , I've been curious before I read the part , Whether tests such as whether the crystal oscillator starts to vibrate can be directly tested in this link . But sort it out from this part , It doesn't seem to be 100% applicable . A very special point is , If some PCB When the crystal oscillator of lacks software and fails to vibrate , Such a test can not directly obtain the real vibration signal . however , Maybe this can be replaced by other inspection methods .