Analysis and judgment of impurities in PCB acid nickel plating solution
(1) Nickel plating is the bottom layer of the plug gold plating has higher robustness, is one of the printed circuit board electroplating species. The quality of the coating is directly affected by the additive impurities and the foreign impurities brought by the electroplating process.
1 copper 0.04 electrolytic treatment
2 Zinc 0.05 electrolytic treatment
3 Lead 0.002 electrolytic treatment
4 Aluminum 0.06 Adjust PH to high
5 6 price 0.01 Adjust PH
6 ** impurities activated carbon treatment
(2) Specific operations excluded:
A. Electrolytic treatment method: current density is usually used, and the anode is corrugated to increase the cathode area. Processing impurities copper, lead and sulfur-containing additives selection, processing time 30 minutes; Iron and zinc impurities are treated by electrolysis.
B, adopt the method of increasing PH: * Transfer the plating solution to the spare tank, add the appropriate amount of nickel carbonate PH to, and add hydrogen peroxide (30%), stir for 2 hours after filtration, and then transfer the plating solution to the plating tank, adjust the PH value to the best range, and then carry out small current treatment, until the plating qualified products.
C, ** impurities treatment method: according to the above increase PH value before adding activated carbon in the spare tank, then add nickel carbonate and hydrogen peroxide, stir for 2 hours, filter, then move to the plating tank, adjust the PH value and small current electrolytic treatment, until plating qualified products.
Single chip emulator is a set of hardware device specially designed and manufactured for the purpose of debugging single chip software.
SCM is the same as PC in the architecture, also includes * processor, input/output interface, memory and other basic units, so the software structure of PC and other devices is similar.
Therefore, microcontroller in the process of software development also need to debug the software, observe the results, eliminate the problems in the software. However, due to the application of the microcontroller problem, it does not have a standard input and output device, limited by storage space, it is difficult to accommodate the software used for debugging procedures, so to debug the microcontroller software, the use of microcontroller simulator. Single chip emulator has the basic input and output device, with the support of program debugging software, so that the single chip developer can input and modify the program through the single chip emulator, observe the results of the operation of the program and the intermediate value, at the same time with the single chip supporting hardware detection and observation, can greatly improve the efficiency and effect of single chip programming.
The early single-chip emulator was a set of vertical devices with a keyboard and a display for inputting programs and displaying running results; With the popularity of the PC, most of the new generation of emulators are using the PC as the standard input and output device, and the simulator itself becomes the interface between the computer and the target system, the simulation way also from the beginning of the machine code development to assembly language, C language simulation, simulation environment and the PC language programming and debugging environment is very similar.
The simulator generally has a simulation head, used to replace the target system in the single chip microcomputer, that is, use the plug to imitate the single chip microcomputer, which is the name of the single chip emulator.
At present, with the microcontroller miniaturization, chip and the wide application of the microcontroller with ISP, IAP and other functions, the application range of the traditional microcontroller simulator has been reduced. And software SCM simulator (that is, SCM simulation program) is widely used, SCM simulation program is running on the personal computer, can simulate the hardware environment of SCM operation to a certain extent, and in the environment to run SCM target program, and can debug the target program, breakpoint, variable observation and other operations, It can greatly improve the debugging efficiency of SCM system. Pure software single-chip emulator is often integrated with the hardware design program released together, so that can develop the single-chip hardware and software synchronously.
PCB is one of the indispensable parts of electronic equipment, it appears in almost every kind of electronic equipment, in addition to fixing a variety of large and small parts, the main function of PCB is to let the parts electrical connection. Since the raw material of PCB board is copper-covered board, copper dumping will occur in the process of PCB production. Then what are the reasons for copper dumping of PCB board? Here is to introduce it to you.
Four reasons for PCB board copper throwing
1, PCB circuit design is not reasonable, with thick copper foil design of too thin line, will also cause excessive line etching and copper.
2, copper foil etching is excessive, the electrolytic copper foil used on the market is generally single-side galvanized (commonly known as gray foil) and single-side plated copper (commonly known as red foil), the common copper is generally more than 70um galvanized copper foil, red foil and 18um below the basic ash foil has not been a batch of copper.
3. Local collision occurs in PCB process, and the copper wire is separated from the substrate by external mechanical force. This defect manifests as poor positioning or orientation, falling copper wire will have obvious distortion, or in the same direction of the scratch/impact mark. Peel off the bad part of the copper wire to see the copper foil surface, you can see the normal color of the copper foil surface, there will be no bad side erosion, copper foil peeling strength is normal.
4. Under normal circumstances, as long as the hot pressing high temperature section is over 30min, the copper foil and the semi-cured sheet are basically combined, so the pressing generally will not affect the binding force of the copper foil and the substrate in the laminate. However, in the process of laminate stacking and stacking, if PP pollution or copper foil surface damage, it will also lead to insufficient bonding force between copper foil and substrate after laminate, resulting in positioning (only for the large plate) or sporadic copper wire loss, but the stripping strength of copper foil near the stripping line will not be abnormal.