Ppm refers to the number of pages per minute, that is, the number of pages printed per minute. It is an important parameter to measure the printing speed of a printer and refers to the average speed of continuous printing. Also refers to the concentration expressed by the ratio of solute mass to total solution mass, also known as ppm concentration.

Ppm is the abbreviation of English part per million, which stands for parts per million. On different occasions, it is often used with some physical quantities to express the accuracy of DC parameters of a device.

2.ppb (indicating concentration unit):

PPb (parts per billion) is a dimensionless quantity, which is the concentration expressed by the ratio of the mass of solute in the solution to the total mass of the solution. It is also called parts per billion concentration (1/kloc-0, one billionth, 10-9), which is often used in the case of small concentration. Similarly, there are parts per million (ppm), and ppb =11000 ppm.

Extended data:

The role of ppm in expressing precision units;

1, which is used to describe the frequency characteristic parameters of the crystal;

For real-time clock, the stability of crystal oscillator frequency directly affects the accuracy of real-time clock. The parameters used to describe the frequency characteristics of a crystal mainly include frequency tolerance, frequency-temperature characteristics and frequency-voltage characteristics, which describe the change of crystal oscillation frequency with the influence of external factors.

Expressed in ppm and ppm/v, the frequency of crystal oscillator is generally in MHz (10 to the 6th power), so the frequency deviation of crystal oscillator with nominal frequency of 10MHz is exactly 1ppm.

Ppm describes the stability of crystal oscillator and is not used to calculate error accumulation. The frequency error represented by the precision order describing the frequency of the crystal oscillator can be used for error accumulation. According to the order of stability and accuracy, crystal oscillators can be divided into stable and inaccurate, unstable and inaccurate, unstable but accurate, stable and accurate.

2. In the quality system, the defective rate is expressed in millions:

1PPM is one in a million. Ppm= number of nonconforming products * 1000000/ batch; It is the unit of DPMO's millions of opportunity defects. In the electronic industry, the statistics of welding quality level is usually based on DPMO to calculate the PPM value of welding quality.

If the error probability of a PCB (the number of solder joints of components on the circuit board) is 1000, the production capacity is 1000, and the fault point is 2000, then its dpmo = (2000 *1000000)/(1000 *).

Baidu encyclopedia -ppm(ppm)

Baidu encyclopedia -PPB (concentration unit)