The understanding that encloses about chip reachs his to understand

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  • source:ACHER CNC Machining
Enclosing original definition is to protect circuit chip to avoid the effect that suffers surroundings, include to come from the influence of physics, chemical respect. And now, the rate that accompanying chip is rapidder and rapidder, power is greater and greater, make chip comes loose hot problem is serious with each passing day, as a result of quality of chip passivation layer rise, the value of the action that encloses in order to to protect circuit function is falling. The chip nowadays is enclosed, it is the crust that shows chip of installation semiconductor integrated circuit is used, rising to put, chip of fixed, sealed, protection and the action that enhance electric heat performance, the bridge that is world of communication chip interior and exterior circuit (the contact on chip goes to those who enclose crust to bring a foot to go up with lead join, these wire that make a foot go up through printed board again and other parts of an apparatus build join) . From the concept that chip encloses we see not hard, the action that chip encloses basically has 4 sides: Sex of protection of sex of the fixed system that cite a base, physics, environment is protected and increase medicinal powder hot. What is to secure the system that cite a base? Chip has exterior the component that makes foot and interior cite a base, interior cites a base very fine, be less than 1.

5 micron, 1 micron is below most circumstance, interior is brought foot and exterior bring solder together with copper between the foot, the exterior ground connection that cite a base, with the action that exchanges to data since circuit board join. The outside system that cite a base uses two kinds of different alloy normally: Iron nickel alloy reachs copper alloy, former the occasion that is used at high strenth and tall stability, and latter has the advantage with conductivity and better thermal conductivity, specific choose which kinds to cite a base, will decide according to actual condition. Physical sex is protected, it is to show chip can avoid the pollution that gets the material such as particle and outside be damaged to it later through enclosing, the requirement that encloses grade to chip is endless also and identical, consume kind of product demand lowest. Environmental sex is protected, can let chip avoid it is normal to suffer the other possibility such as damp to disturb chip the effect that functional gas produces to its regular job. Increase medicinal powder hot, be quantity of heat can produce when working considering all semiconductor product, and the regular job that can affect chip when quantity of heat reachs certain limit. In fact, all sorts of material itself that enclose body can take away one part quantity of heat, of course, to chip of most calorific generous, besides undertaking dropping in temperature through enclosing material, still need to consider additional on chip installation carbon fin of a metal or fan are better with achieving medicinal powder hot effect. Enclosed classification according to the material that pack, it is OK to enclose cent is: The metal is enclosed, pottery and porcelain is enclosed and plastic enclose, among them, the metal is enclosed basically use at war industry or space technology, without commercialize product; pottery and porcelain to enclose the action photograph that encloses with the metal similar, basically also use at martial product, the product; that little part is commercialized is plastic enclose use at consuming an electron, because its cost is low, craft is simple, reliability is high and the market share that owns the majority. From air-tightness angle classification, but will enclose cent to air-tightness is enclosed and be not air-tightness, among them, the metal is enclosed and pottery and porcelain is enclosed belong to air-tightness to enclose, plastic belong to blame air-tightness to enclose. According to with the join means of PCB board, enclose can divide for PTH and SMT, PTH is the abbreviate of English Pin-through-hole, chinese interpreter is the type that insert aperture or via type, this kind of scarcer and scarcer on market;SMT is the abbreviate of English Surface-mount-technology, the surface that the interpreter comes over even if often says sticks outfit type, at present major IC all uses SMT on the market. According to enclose an appearance to be able to classify for: SOT, QFN, SOIC, TSSOP, QFP, BGA, CSP, this is according to enclose form and craft more and more advanced and complex come sort, among them because CSP used Flip Chip technology and naked piece enclose, reached chip area / enclose area =1: 1, for at present ritzy technology. Oneself think, deciding two crucial factors that enclose a form is to enclose efficiency and the number that cite a base. Why to tell so? Enclosing efficiency above all is to show chip area is compared with what enclose an area enclose efficiency to rise, the principle is both is close to as far as possible 1: 1, enclose the effect best; next, the number that cite a base is more, more advanced, difficulty of the craft when enclosing also increases accordingly, in principle brings a foot to want as far as possible short in order to reduce delay, leave the space between the foot as far as possible far, in order to assure each other noninterference, raise function; of course, be based on come loose to ask hotly, enclose it is good to jump over Bao Yue. CNC Milling CNC Machining