The properly and electrostatically measured taping materials are used for the components, but attention should be paid to the fact that there is some danger the parts absorb on the top
tapes to cause a failure in the mounting and the parts are destructed by static electricity (more than 1kV : 1J, 2A, 2B, 2E 0.5kV : 1E, Human Body Model 100pF 1.5kΩ) to change the
resistance in the conditions of an excessive dryness or after the parts are given vibration for a long time as they are packaged on the tapes. Similarly, care should be given not to apply the
excessive static electricity when mounting on the boards.
●
Ionic impurities such as flux etc. that are attached to these products or those mounted onto a PCB, negatively affect their moisture resistance, corrosion resistance, etc. The flux may
contain ionic substances like chlorine, acid, etc. while perspiration and saliva include ionic impurities like sodium (Na
＋
), chrorine (Cl
−
) etc. Therefore these kinds of ionic substances may
induce electrical corrosion when they invade into the products. Either thorough washing or using RMA solder and flux are necessary since lead free solder contains ionic substances.
Washing process is needed, before putting on moisture proof material in order to prevent electrical corrosion.
●
Please pay attention that the top of an iron does not direct touch to the components. There is a risk that may cause a change in resistance. Take care that another risk may happen that
the protecting coat is carbonized in an instant when touched directly by the top of the iron, also climatic-proof for electric corrosion or insulation of protecting coat may be dropped down.
Be sure not to give high temperature on the top of the iron as it will degrade the protecting coat.
●
Avoid storing components under direct sun rays, high temperature/humidity. Direct sun rays will cause quality change of taping and difficulty of keeping appropriate peeling strength. 5∼
35℃/35∼75%RH, there is no deterioration of solderability for 12 months, but take special care for storing, because condensation, dust, and toxic gas like hydrogen sulfide, sulfurous acid
gas, hydrogen chloride, etc. may drop solderability.
Updated the firmware of PYBCNV2 and fixed a reboot bug.https://github.com/micropython-Chinese-Community/MicroPython_firmware/tree/master/pyboardCN_V2
or
https://gitee.com/microbit/MicroPython_firmware...
I am using the development board (STEVAL-IDB009V1) to test the ADC Polling Demo program and found that when the ADC1 pin is selected for input, the voltage value read back is normal, 2.7V, but when th...
I am a beginner in AVR and I output a PWM signal, but the output signal level is negative.How can I perform the flip processing to make the signal level positive?...
[align=left][color=rgb(51, 51, 51)][size=17px][font=微软雅黑]In recent years, the field of robotics has continued to heat up, and a large number of robotic products have emerged, such as robot dogs, drone...
introduction
With the continuous optimization of surface mount technology (SMT) and the rapid development of chip component manufacturing technology, the application of chip mounters in the el...[Details]
1. Introduction
Automobile pollution is one of the most important issues that people are most concerned about and need to solve urgently. As an important method for detecting automobile exhau...[Details]
0. Introduction
In daily life, we often see some special-purpose vehicles. When these vehicles pass through intersections, they often obtain the right of way at intersections by temporarily op...[Details]
In recent years, lighting has become an important area that countries around the world are targeting to promote energy conservation and environmental protection. According to statistics, about 20% ...[Details]
1. System Structure
This system is a simulation system of indoor air-conditioning temperature/humidity control system. The data acquisition and control center collects temperature/humidity...[Details]
The concept of state machine
State machine is an important concept in software programming. More important than this concept is its flexible application. In a clear and efficient program, ther...[Details]
Capacitors
are basic components in various electronic devices and are widely used for bypassing, coupling,
filtering
, tuning, etc. in electronic circuits. However, to use capacitors,...[Details]
Abstract: The output of high-range acceleration sensor is less than 10 mV under the excitation of small signal. The noise of traditional test system may cover such small voltage signal, so that hig...[Details]
introduction
At present, measuring instruments are developing towards networking, and each individual embedded instrument will become a node on the Internet. This system realizes the network...[Details]
1 Introduction to LED
With the development of science and technology, people have higher and higher requirements on automobile light sources. LED (Light Emitting Diode) has gradually attracted...[Details]
Against the backdrop of global warming, energy conservation and emission reduction have become a global hotspot and focus, which has also sounded the clarion call for the take-off of the LED lighti...[Details]
This article discusses the six design steps of LED lighting system design in detail: (1) determine the lighting requirements; (2) determine the design goals and estimate the optics; (3) the efficie...[Details]
LED is now known as the fourth generation of light sources. High-power LED has many advantages over traditional light sources in outdoor lighting.
1 LED lamps have high light efficiency
C...[Details]
This article focuses on closing the feedback loop of an isolated power supply using a TL431 shunt regulator. The article discusses a method to extend the bandwidth of the power supply control loop ...[Details]
MicroPython Open Source section
京公网安备 11010802033920号
EEWORLD
