Repair motherboard, choose what kind of multimeter, soldering iron?

Soldering tools

1. Soldering iron, according to the use of the environment, the use of different, there can be roughly two choices. If it is in a fixed location, and the soldered device is sensitive to static electricity, it is recommended to buy 936 adjustable thermostatic ESD (ESD, anti-static) soldering station, this type of soldering iron part of the soldering iron is more compact, the use of flexible, the general power of 50-60W, the highest temperature can be adjusted to 480 ° C., which can effectively prevent the CMOS components of the static breakdown, which do not need to consider the soldering iron of the static electricity problem, only need to consider the human body Static electricity problem. This soldering iron can be based on the specific requirements of the welding to select a different iron head (special type of iron head is more expensive), the price is now less than 200 yuan. As the main body of the soldering station has a transformer inside, heavier, larger, inconvenient to carry, so it is not suitable for on-site use. Adjustable thermostatic ESD soldering station of many manufacturers, foreign more well-known brand is Japan's first white light (KAKKO), the 936 type mentioned earlier, is the model of white light. In fact, the white light of the product is not the most excellent, but it entered China earlier, when the price is still acceptable to the Chinese people. When the cell phone repair industry was in its infancy, White Light's 926 soldering station was highly regarded by the industry, and it was really a sight to behold, and I just started using it. However, the Chinese ability to push the boundaries of innovation, not only copied the 926, 936 soldering station, but also developed their own digital adjustable, from the appearance of the function has been improved. I think the white light in our domestic market has no ordinary soldering station to fight back, lead-free soldering station market will not have much to do. In the domestic production of soldering station of the company is relatively well-known: Jiangsu fast grams, Shenzhen Antaixin, blue special, etc., as the field use, the purchase of ordinary adjustable thermostatic soldering iron is a better choice, such as Guangzhou Huanghua Electronic Tools Co., Ltd. production of 905, 906-type, the maximum power of 60W, a better solution to the number of layers of copper foil circuit boards, heat dissipation area is large, too fast heat dissipation problems. This type of soldering iron price is generally less than 50 yuan, but do not choose 907 type, I made the door when using it, has found many problems, which is not comfortable to hold, the temperature adjustment knob is easy to mistakenly move the problem is the most prominent. Another reminder to buy a soldering iron, should not choose the tip of the soldering iron is very sharp. We will generally think that the tip of the soldering iron is suitable for welding the pin spacing of small chip components, this is a misunderstanding. From the actual point of view of the tip of the soldering iron, the tip of the soldering iron temperature is also lower, which caused the liquidity of the solder becomes poor, is not conducive to drag welding welding. Here we recommend a knife tip soldering iron head, which I learned when I studied in Beijing. The shape of this soldering iron head is similar to the carving knife used for carving, with brevet and tip part. Because it has a wider soldering surface and a certain thickness, the temperature is significantly higher when the soldering station is set at the same temperature than with a pointed iron head, and the tip of the knife head is quite flexible when it is used. I had some trouble getting used to it at first, but after a while it was fine, and I'm really comfortable using it to solder high-density QFP devices.

2. Hot air gun, which is welding SMD (surface mount) components necessary tools. There are several manufacturers of products on the market, such as the previously mentioned Jiangsu Quick, Shenzhen Antaixin, Japan White Light and so on. As with the thermostatic soldering station, the domestic hot air gun from the imitation of Hakko 850 type to start, and now also has a certain degree of independent research and development capabilities. General thermostat type (852 or 853) from more than 200 yuan to 700 yuan. In general, the market to buy a thermostatic hot air gun welding small SMD components can be, but the slightly larger chips are prone to long heating time, and even welding down the problem. And ordinary non-thermostatic heat gun (850-type) compared to the "fire" to "fierce" much, blowing a slightly larger chip is obviously much faster, but the longer the use of time is the higher the temperature, easy to blow the circuit board paste, more "! Inaccurate". Why is the thermostatic heat gun will generally appear not hot problem? I think this is related to the manufacturers of unreasonable design, such as temperature measurement with the placement of thermocouples, heating wire selection, and control issues (I think it is not the use of PID control better it). Tell an interesting example, I use the Antaixin 8305 type thermostatic hot air gun with the previous talk about the general hot air gun on the contrary, it is welding a large chip is very good to use, demolition of small parts on the contrary, and its power as high as 1400 W. Here it is recommended that we do not buy gas hot air gun, because it is more difficult to control the temperature of the 96 years when I bought a gas hot air gun with an electronic ignition found that the ignition part of the fire only to make a few times to make it bad! With a match to point, the jet of air but blew out the match, worse often components are removed, the circuit board is also bulging. For cost considerations do not want to buy ready-made hot air gun brother, here I introduce a homemade simple hot air gun method: buy a 500W (there are 700W) plastic torch (repair plastic products with the price of less than 50 yuan, selling electronic tools are available, buy the kind of temperature control function), and then buy a dimming lamp with the dimming control circuit board (selling home appliance parts places are sold at a price of about 2 yuan). The board can be used as a dimming control board for a dimming lamp (sold in appliance parts places for about 2 dollars). Plastic torch disassembled, find out the power supply of the wind motor into the line, disconnect one end, the dimming control circuit board will be strung in. In the plastic torch handle part of a slightly larger hole than the dimming potentiometer handle, the dimming potentiometer fixed, the plastic torch parts back, OK, now you have a "thermostatic speed control hot air gun". The reason why the motor speed control is to avoid the hot air wind speed is too fierce, will be small pieces of blowing.

3. Tin sucker, the most commonly used disassembly essential tools. I initially used a tin soldering iron (I do not know if it is not imitation of the white light of the 019-type electric heat suction pump, anyway, the structure is the same) to remove components, but the tin soldering iron is indeed very, very very "short-lived" (suction mouth too bad, "leakage"), the price is not cheap. Not cheap, I finally can not afford to use, but fortunately I knew that the manual solder sucker is better than the soldering iron. From 1995 I began to use manual tin sucker, the first time to buy is produced by Guangzhou Gaojie. When I first started to use I do not dare to let the mouth of the tin sucker and soldering iron next to, carefully, and then see that the plastic suction nozzle is indeed resistant to high temperatures, only dare to boldly use. The quality of this Kojie tin sucker is very good, when I found that its internal sealing is not good, I will use sewing machine oil drops in the sealing ring, OK, the sealing is as good as new. The first manual tin sniffer just didn't work anymore, so I bought a second one, which was still a Goggle, but unfortunately the quality of the Goggle seemed to have taken a nosedive, and it didn't take more than a few days for this one to "give up on me". After that, I bought a few other brands of tin sucker, or because of sewing machine oil maintenance sealing ring caused by the expansion of the ring or because of the poor quality of the plastic nozzle and discarded. About 1997 by chance a tool dealer recommended to me a trademark is only hummingbird manual tin sucker (model US140), made in the United States, the price is not expensive (at that time to 65 dollars, right). Bought a try, the good guys effect is extraordinary, suction tin volume, less residual tin, feel good, than previously bought obviously better. Of course there are shortcomings: must be diligent maintenance, otherwise the life will be greatly discounted. With the previous sewing machine oil maintenance sealing ring caused by the expansion of the rubber ring of the lesson, I decided to use and the original similar "maintenance products" to maintain this kind of tin sucker. I found the ideal grease from Zhengzhou Dongming Electronics, the effect is very good, after the maintenance of tin sucker sealing is satisfactory. Later Zhengzhou Dongming Electronics that kind of grease is no longer sold, I found from the local VCD with the grease, the effect is just as satisfactory. Coincidentally, this year I went to Beijing and found that I used this sucker is the United States Essen (hanson) produced, known as the world's best sucker stick (and we call it different). Because buy this kind of tin sucker more, found that this kind of tin sucker different batches of quality also have differences, now this kind of problem has a tendency to become more and more intense. In the purchase of the selection must be used to try to see if there is a sense of offense card, the more obvious this feeling is the more inappropriate to buy. Have also bought other manufacturers of products, such as Taiwan's Bao Gong's, miscellaneous CT140, etc., the feeling is significantly less than the Essen US140, especially when repairing the monitor. Due to the monitor's large solder joints (especially line output transformer, the shield of the video amplifier board), other brands of products are very easy to plug, US140 is less of such problems. Now on the market also has a tin gun (the appearance of a gun-shaped) in the sale, such as Guangzhou Gaojie (should be imitation white 808 portable tin gun, right), Harbin Coretec also had a similar product. The price of Coretta is still affordable, so I bought two of its products (at that time, I have a classmate in Coretta, so the second time is directly from the Coretta to take the goods, a long time no news of the Coretta, and now I do not know if the Coretta still exists?) The first time I bought their earlier products. The first time I bought their earlier products (about 1998), as if the power of more than 30 watts, I feel that the power is not enough to absorb the soldering on the double-sided circuit board EPSON LQ1600K CPU (UPD7810) seems to be "incompetent", and suction nozzle (copper) is very easy to damage. Crestec also found these problems, so there is a second generation of products, the power is increased, and the nozzle is replaced by a steel nozzle. I use the feeling is that the power seems to be still not enough, the steel nozzle is not easy to damage, but the effect of damage to the circuit board is also very obvious (too hard, very easy to poke the copper foil). Gaojie's one is about $, too expensive to try. I found through practice this kind of tin gun limitations are quite large, demolition of a large area of double-sided circuit boards are still not satisfactory (I have a buddy has a white 484 tin gun, than the above mentioned Coretec and Gaojie's more advanced, but the effect is no better than that), not to mention the demolition of multi-layer boards. To get to the bottom of it, I think the design starting point is a problem, in the latter article I will talk about this problem.

4. Suction tin braid, welding SMD components in addition to the tin necessary. When we weld such as ordinary 80 feet of QFP SMD integrated IC, simply blow down the original IC with a hot air gun, and then leave residual solder pads for hot air leveling, and then the IC to be welded in the original position, with a hot air gun heating can be. But when the IC pins more, spacing hours, with the previous method is difficult to align the original position, resulting in welding misalignment. This is because the original pad on the residual solder on the alignment of the work of the impact is obvious. At this time with the solder suction tape on the pads of residual solder suction away, the alignment work can be carried out smoothly, after the completion of the alignment, the use of soldering iron on the IC drag welding can be. Suction braid selection should be based on the size of the SMD component pad to choose, one is the width of the suction braid, another is the thickness of the suction braid, the smaller the pad, the narrower the width of the suction braid is required to require the thickness of the thinner. Because the wider the thicker the soldering iron requires the higher temperature, it is more likely to appear in addition to the tin when the soldering tin braid due to the low temperature and pads soldered together, in the movement of the soldering tin braid will be brought up by the pad in place, or even fall off the problem. Of course, because the narrower and thinner tin absorbing braid (while the amount of tin absorbed is also less), the price is also more expensive, or to calculate the economic account. There are many manufacturers on the market to absorb tin braid production, domestic generally wider and thicker (process technology issues), imports, I have only seen the Japanese goot, I can find the narrowest and thinnest on the market in Harbin to absorb tin braid is its products. Here to introduce a substitute for tin braid method, the market now sells multi-stranded fine-core aviation wire, this kind of wire has a variety of specifications, the wire surface is said to be silver-plated (I do not know whether it is true), solderability is very good, very suitable for the suction of tin with. I use the result is very good, just in line with our requirements of the aviation wire may not be very good to buy now are out of stock.