Ten Misunderstandings of Circuit Reliability Design (2)

Misunderstanding 6: The device is very simple, it doesn’t matter whether there is a Datasheet or not.

When designing, you must get the Datasheet of all the devices, and then read all the graphs and parameters on it, and finally establish a connection with these curves in the design. The following figure is the V-I characteristic curve of the diode. It is necessary to carefully confirm the static operating point of the device in our circuit when designing.

Misunderstanding 7: Maintainability has nothing to do with me.

What is the purpose of electronic product reliability work? It is to make money. What do you rely on to make money? Increase income and throttling. It is difficult to increase income and easy to reduce expenditure. Don’t always think about saving on material costs. Material costs are saved, and maintenance costs are high. The best way is to pay attention to maintainability and save this part of the cost. This is a genuine profit.

Misunderstanding 8: Poor process control means that there are no good craftsmen.

Poor process control is not just a problem for craftsmen, it is the construction of a value chain. The requirements of the design engineer for the device, the selection of the manufacturer of the purchasing engineer, the control content of the inspection link should be designed in the part of the key indicators of the device, the detection method should not introduce the failure mechanism and damage of the component, and the assembly link should not introduce damage (peak temperature control of the welding furnace, anti-static treatment of the manual welding table, etc.). The factory inspection link should check the part of the device parameter drift that may cause product failure, and the maintenance link should not introduce failure.

It can be seen from the above that the two process engineers can guarantee that there is a problem. Therefore, it is concluded that the specific method is to establish consistency. The premise of consistency is that the designer provides sufficient, primary and secondary technical information. The process is only based on the design drawings and design documents to ensure that the manufacturing reliability is infinitely close to the design reliability.

Misunderstanding 9: The relationship between the MTBF value and the failure rate of a single specific machine.

MTBF is a macro and statistical concept, and a single machine failure is a micro and specific concept. Customers like to ask the question “The MTBF value of your product is 10,000 hours, so if I buy one, there will be no problems within 10,000 hours?” Let me Speaking of their conversion relationship, would you tell me whether it is 1km or 1kg?

Misunderstanding 10: Strengthening testing can solve reliability problems.

Since this problem can be listed as one of the top ten misunderstandings, its definition is naturally wrong. There are three conclusions:

1. Some problems cannot be detected at all through simulation test experiments.

2. Testing means = engineering calculation + specification review + simulation test + electronic simulation.

3. The corresponding low temperature working time cannot be calculated through the results of the temperature enhancement test.

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