PCB manufacturing reliability definition

1. Although there is a consensus that reliability is an important attribute of PCB manufacturing products, the definition of reliability and the more popular ones are as follows:

(1) Definition 1: Refers to the probability that the product will perform the expected function in a specified working environment and within the specified lifetime, in a way that can meet or exceed the user's expected value, generally expressed by R(t).

(2) Definition 2: The probability that the product can perform the specified function under the specified conditions and within the specified time.

2. Failure rate

The reasons for product failure are:

(1) Problems caused by the product's own design defects, including solder joints.

(2) Related problems in product production and quality control.

(3) Differences due to user use.

(4) The user actually improperly maintains and improperly uses or abuses the product.

A. Early failure period

Some PCB manufacturers specialize in products aging before they leave the factory to reduce the early failure of products after entering the market.

B. Useful life

The products in this region have experienced aging, reaching its lowest level of failure, characterized by a near-constant failure rate. This working interval is usually the part of the product design phase and the relative weight laggest of the reliability activities, which is the most important stages of the reliability prediction and assess activity.

C. Depletion period

When the failure rate is relatively high, the product should be replaced or repaired, and the replacement plan should be based on the perception of failure rate at this stage.

Reliability optimization must consider these three life stages, and early failures must be eliminated by reducing process variability and system procedures for control screening and aging testing; application-related failures must be minimized by preserving appropriate design margins. Depletion period failures must be minimized by regular preventive replacement. In order to avoid early failures, initial design and engineering management are very important, including the preservation and storage of components. However, no matter how to design, there will be unpredictable defects. If you want to avoid these defects, you need to conduct a full inspection and a screening test that is higher than the market use load of the PCB manufacturing products.