Summarize the sharing of soldering skills for SMD components
1. Soldering iron
Hand-soldered components, this must be indispensable. Here I recommend the one with a sharper tip, because it can accurately and conveniently solder a certain pin or a few pins when soldering a patch chip with dense pins (PS: I thought it was like this in the early days) , Later, after cooking, I found that the knife head is better!). An adjustable constant temperature electric soldering iron is your best choice, preferably with a digital display (adjustable temperature and stable temperature, there are two kinds of single handle temperature adjustment type and soldering station). It should be noted that the above internal heating type and external heating type usually do not have a power switch, and they will be heated when plugged in, and they must be turned off to cool down. As the saying goes, a good horse needs a good saddle. Then the soldering iron head is the saddle of the horse (soldering iron). The selection of the soldering iron tip should be determined according to the contact surface of the object to be welded. For example, for ordinary plug-in components, we mostly use horseshoe heads (large contact surface); small SMD components can be pointed or curved (soldering dense components); for conventional chips, cutter heads can be used (convenient drag welding). Of course, the more advanced DIY method is to polish the unique shape of the soldering iron tip according to your own needs.
2. Solder wire
Good solder wire is also very important for SMD soldering. If conditions permit, use as thin a solder wire as possible when soldering SMD components, so that it is easy to control the amount of tin, so that there is no need to waste solder and absorb tin. Chinese name: solder wire, solder wire, tin wire, tin wire, English name: solderwire, solder wire is composed of tin alloy and additives, the alloy components are tin-lead, and lead-free additives are evenly poured into the middle of the tin alloy parts. Different types of solder wire have different additives. The additive part is to improve the auxiliary heat conduction of the solder wire during the welding process, remove oxidation, reduce the surface tension of the material to be welded, remove oil stains on the surface of the material to be welded, and increase the welding area. The characteristic of solder wire is a tin alloy wire with a certain length and diameter, which can be used in conjunction with electric soldering iron or laser in the welding of electronic components.
The difference between leaded and lead-free solder wire:
1. The difference between leaded and lead-free solder wire is only the difference in content.
2. Lead-containing solder wire needs to be artificially added with lead. The best known soldering ratio is tin-lead solder wire (national standard: tin content 63%, lead content 37%).
3. Lead-free solder wire also contains very little lead, and there is no completely pure metal product at present. Usually lead-free solder wire is called lead-free solder wire. Lead-free does not mean that it does not contain lead at all. Lead-free means that the lead content is relatively low, which can be roughly regarded as lead-free. The EU defines lead-free standards as: 1000PPm. Considering the possibility of further pollution in welding and post-processing, in order to ensure that the customer's finished product meets the EU standard, the lead content of the general solder wire will be much lower than this standard.
4. Both leaded and lead-free solder wires will corrode the tip of the soldering iron, because the lead-free soldering temperature is higher than that of the leaded solder wire, and the alloy composition is different, the lead-free solder wire is more likely to corrode the soldering iron, due to lead-free requirements And corrosiveness, it is recommended to use a lead-free special electric soldering iron when soldering lead-free tin wire.
3. Tweezers
The main function of the tweezers is to conveniently pick up and place the chip components. For example, when soldering a chip resistor, you can use the tweezers to hold the resistor and place it on the circuit board for soldering. The tweezers require a sharp and flat front end to facilitate clamping components. In addition, for some chips that need to be protected from static electricity, anti-static tweezers are required.
Anti-static tweezers are also called semiconductor tweezers, static-conductive tweezers, which can prevent static electricity. They are made of carbon fiber and special plastic, and have good elasticity. Lightweight and durable, no ash, acid and alkali resistance, high temperature resistance, can avoid traditional anti-static tweezers from polluting products due to carbon black, suitable for the production and use of precision electronic components such as semiconductors and ICs, and special uses. Anti-static tweezers are made of special conductive plastic material, which has the characteristics of good elasticity, light use and static discharge, and is suitable for the processing and installation of components sensitive to static electricity. Surface resistance: 1000KΩ—100000MΩ. Anti-static tweezers are suitable for the production of precision electronic components, semiconductors and computer magnetic heads and other industries. If you use anti-static tweezers made of carbon fiber and special plastic, it will not shed dust, acid and alkali resistance, and high temperature resistance, which can avoid the traditional anti-static tweezers from polluting products due to carbon black.
4. Tin strip
When soldering SMD components, it is easy to have too much tin.
Especially when soldering dense multi-pin SMT chips, it is easy to cause two adjacent pins or even multiple pins of the chip to be short-circuited by solder. At this time, the traditional tin absorber is useless, and a braided tin absorber is needed at this time. 5. Rosin Rosin is the most commonly used flux in soldering, because it can precipitate oxides in solder, protect solder from oxidation, and increase the fluidity of solder. When soldering in-line components, if the components are rusty, first scrape them up, put them on the rosin and iron them with a soldering iron, and then tin them. When soldering SMD components, rosin can also be used as a tin-absorbing belt with copper wire in addition to the role of soldering.
6. Solder paste
Solder paste can be used when soldering iron parts that are difficult to tin, which can remove oxides on the metal surface, which is corrosive. When soldering SMD components, it can sometimes be used to "eat" solder to make the solder joints shiny and firm.
7. Heat gun
A heat gun is a tool that uses the hot air blown out of its gun core to weld and disassemble components. The process requirements for its use are relatively high.
Heat guns can be used for everything from removing or installing small components to large integrated circuits. In different occasions, there are special requirements for the temperature and air volume of the heat gun. If the temperature is too low, the components will be soldered, and if the temperature is too high, the components and circuit boards will be damaged. Excessive air flow can blow away small components. For ordinary patch welding, a heat gun may not be used, so I won't describe it in detail here.
8. Magnifying glass
For some SMD chips with extremely small and dense pins, it is necessary to check whether the pins are soldered normally and whether there is a short circuit after soldering. At this time, it is very laborious to use the human eye, so a magnifying glass can be used to check each The welding condition of the pins.
9. Alcohol
When using rosin as a flux, it is easy to leave excess rosin on the board. For the sake of appearance, you can use alcohol cotton balls to wipe off the residual rosin on the circuit board. Scrubs, glue, etc. Manual soldering steps of SMD components - After the electric soldering iron has learned about the SMD welding tools, the soldering steps are now described in detail.
