朋店 Some friends on the Int可事ernet seem to have視作 some misunderstandings about t光朋he temperature setting o北化f hotbar's therm飛為odies and the actual m身唱easured temperature. Some people他看 think that as long as the temper有森ature of hotbar is set to 400 &你花deg; C, the temperatur計白e of its hot indenter mu知很st reach this temperature before it 劇錯is normal. However, the act去銀ual temperature on the meas小地uring board is only ab師家out 280 ° C, so there is a q短黑uestion about the actual 要間temperature of the hot國林 indenter.
I have a good understanding廠內 of the misunderstanding caused by th跳少e design and prin年子ciple of hotbar hot press welding mach白師ine. Let me use iro是放n as a metaphor to explain. When we set兒行 the temperature 河拍of the iron at 400 ° C, the t紅兵emperature actually can be rea吧低ched. However, when we put t他在he iron on the solder 行事and parts, the 日綠temperature of the solder and parts is物習 close to the room temperature, so 風讀the iron head actually 海話transmits The temperature 媽長of lead to solder and p化能arts is not up to 400 ° C朋購, which may be abo購物ut 260 ° C in general, 為他while the melting point of 路煙sac305 solder is only 217 ° C, so 就費it can be used 訊車for soldering. Howeve子老r, if there is a large piece of ground體吃ing copper foil on the PCB pad商北, the temperature los厭票s of soldering iron head will multi小藍ply, sometimes it will even ca黃很use the problem of false sold的舊ering or failure to so頻筆lder.
Looking back, the sam計日e is true for hot道年bar's hot indenter. 音這Although it is set to 400 ° 的靜C, the actual temp短媽erature of solder paste 為我will not be as hi店黃gh as 400 ° C after輛樹 contacting the PCB pad. If there is s月請uch a high temperature她不, many electronic parts and c看鐘ircuit boards should not be able to wit技從hstand such a temperature. This is beca懂生use the conduction of heat decre照技ases with time and但很 distance.
&n喝樹bsp;It is recommende校店d to measure the快刀 temperature curve章些 of the hotbar hot press welder onc中雨e according to the reflow temperatu雨影re curve, and it is b可訊etter to select at看森 least three pads (ground低區ing pad, power pad, common pad) whe子線n measuring the temperature, be空低cause grounding and power p計場ad are usually c大少onnected to large pieces of copper北少 foil, which is easy to cause heat高錯 loss. The purpose of connectin麗姐g common pads is to avoid temperature T東志he setting is too high to cause co內票king.
As for the machine setting of ho東金tbar hot press welding 頻文machine, there are basically 機能at least two settings, and算體 each stage can set its要購 own temperature an黑那d time, which is similar to the工什 reflow oven of two temperature zon南和es, and this is one of關短 the reasons why th學弟e welding time of 錢員hotbar can be red務笑uced to such a short 照說time. As for the relationship be高員tween temperature and t拍事ime, as soon as the p她飛ulse current on t動著he hotbar machine is turned on, it mean風就s heating at full sp地生eed until the set temperature and tim自間e, but the temperature he區門re measures the solder on the 水地hot indenter instead為答 of the circuit board, so the船見 temperature settin從吧g must be much higher 明中than the melting tempera制你ture (217 °站說 C), which is similar to reflow'煙劇;s temperature setting, wh低事ich is basically higher than the ac是知tual measurement To the same te討什mperature.
The first stage of能長 heating aims at但民 preheating, which is generally set a少風t about 150 ° c-170 ° C. Thi金吃s temperature is also th術妹e temperature that FPC can bear for a l鄉山ong time without damagi小歌ng its structure. G文和enerally, it takes about輛還 2-3 seconds to heat the temp看妹erature of FPC, solder paste a空畫nd circuit board to a certain exte錯錯nt first, so as to avoid unpredictable 去影problems caused by rapid temp森器erature rise For exampl好費e, de lamination can also remove water報腦 vapor. In addition, it is also nec在票essary to consider whether the pad of資生 hotbar FPC is exposed to the back. If場現 it is only a single-la件是yer plate and there is no pad on 樹國the back, it will be 文制very unfavorable for老區 heat conduction to the solder做歌 paste. At this time,個風 it may be necessary to飛明 increase the preheating temperature.
The second stage is the real 土國solder temperature, so the t雜花emperature of lead-free solde術動r is generally set at about 360 ° C會近 ~ 400 ° C, so it is necessar關費y to make the ac間在tual temperature of solder 公花fall between 230 ~ 250 &這線deg; C, so as to街劇 determine the meltin麗冷g tin without scor畫森ching the soft plate購呢, and the time is generally s現校et at about 4 ~ 8 seconds. I女得t is recommended to determine the農錯 temperature curve base中明d on the characteristics of each plate 和計and the actual measurement Settin自厭g of temperature and time in each校現 stage.
Finally, I also stress th月書at the temperature measurement req玩多uired for hotbar soldering should be th我美e temperature on the solder paste solde樹南r joint of PCB, which is a地場lso the actual temperat兒靜ure transmitted to PCB after t討湖he hot indenter is heated, and銀外 it is also the temperature when th刀山e solder is actually welded. The我木refore, generally, the temper微中ature curve of hotbar hot press w關女elding machine sh用內ould be measured in thermal mo窗友de Couple is connected to t民舊he hotbar pad of PCB,西東 and then the PC多到B is actually heated with ho可我t indenter, so the measured tempe風不rature is the te場生mperature that can be use跳做d in welding.
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