Kusetyenziswa kwanjani PCB for IC package heat dissipation?

The first aspect of PCB design that can improve thermal performance is the PCB device layout. Whenever possible, high-power components on the PCB should be separated from each other. This physical separation between high-power components maximizes the PCB area around each high-power component, thereby helping to achieve better heat conduction. Care should be taken to isolate temperature-sensitive components on the PCB from high-power components. Whenever possible, the installation location of high-power components should be far away from the corners of the PCB. A more central PCB location can maximize the board area around high-power components, thereby helping to dissipate heat. Figure XNUMX shows two identical semiconductor devices: component A and component B. Component A is located at the corner of the PCB and has a die junction temperature that is XNUMX% higher than component B because component B is located closer to the middle. Since the board area around the component for heat dissipation is smaller, the heat dissipation at the corner of component A is limited.

How to use PCB for IC package heat dissipation?

The second aspect is the structure of the PCB, which has the most decisive influence on the thermal performance of the PCB design. The general principle is: the more copper in the PCB, the higher the thermal performance of the system components. The ideal heat dissipation situation for semiconductor devices is that the chip is mounted on a large piece of liquid-cooled copper. For most applications, this mounting method is impractical, so we can only make some other changes to the PCB to improve the heat dissipation performance. For most applications today, the total volume of the system continues to shrink, which has an adverse effect on heat dissipation performance. The larger the PCB, the larger the area that can be used for heat conduction, and it also has greater flexibility, allowing enough space between the high-power components.

Whenever possible, maximize the number and thickness of PCB copper ground planes. The weight of the ground layer copper is generally relatively large, and it is an excellent thermal path for the entire PCB to dissipate heat. The arrangement of wiring for each layer will also increase the total proportion of copper used for heat conduction. However, this wiring is usually electrically and thermally isolated, which limits its role as a potential heat dissipation layer. The wiring of the device ground plane should be as electrical as possible with many ground planes, so as to help maximize heat conduction. The heat dissipation vias on the PCB under the semiconductor device help heat to enter the buried layers of the PCB and conduct to the back of the circuit board.

To improve the heat dissipation performance, the top and bottom layers of the PCB are “golden locations”. Use wider wires and route them away from high-power devices to provide a thermal path for heat dissipation. The dedicated thermal board is an excellent method for PCB heat dissipation. The thermal board is generally located on the top or back of the PCB, and is thermally connected to the device through direct copper connections or thermal vias. In the case of inline package (packages with leads on both sides), this kind of heat conduction board can be located on the top of the PCB and shaped like a “dog bone” (the middle is as narrow as the package, and the area away from the package is relatively small. Large, small in the middle and large at the ends). In the case of a four-side package (there are leads on all four sides), the heat-conducting plate must be located on the back of the PCB or enter the PCB.

Uyisebenzisa njani i-PCB kwiphakheji ye-IC yokuchitha ubushushu?

Ukwandisa ubungakanani bebhodi ye-thermal yindlela ebalaseleyo yokuphucula ukusebenza kwe-thermal yephakheji ye-PowerPAD. Ubungakanani bepleyiti yokuqhuba ubushushu obahlukeneyo bunempembelelo enkulu ekusebenzeni kwe-thermal. Iphepha ledatha yemveliso enikezelweyo ngohlobo lwetheyibhile ludwelisa ngokubanzi olu lwazi lobungakanani. Nangona kunjalo, kunzima ukulinganisa impembelelo yobhedu olongezelelweyo lweePCB zesiko. Ukusebenzisa izixhobo zokubala ezikwi-intanethi, abasebenzisi banokukhetha isixhobo baze batshintshe ubungakanani bephedi yobhedu ukuqikelela impembelelo yayo ekusebenzeni kokutshatyalaliswa kobushushu kweePCB ezingezizo zeJEDEC. Ezi zixhobo zokubala zibalaselisa impembelelo yoyilo lwePCB ekusebenzeni kwe-thermal. Kwiphakheji enamacala amane, indawo yepedi ephezulu incinci kunendawo yepadi eveziweyo yesixhobo. Kule meko, ukungcwatywa okanye umqolo ongemuva yindlela yokuqala yokufezekisa ukupholisa okungcono. Kwiiphakheji ezimbini zomgca, sinokusebenzisa “ithambo lenja” isimbo sephedi ukukhupha ubushushu.

Okokugqibela, iinkqubo ezinePCB ezinkulu zinokusetyenziselwa ukupholisa. Kwimeko apho izikrufu ziqhagamshelwe kwipleyiti eqhuba ubushushu kunye nenqwelomoya ephantsi yokuphelisa ubushushu, ezinye izikrufu ezisetyenziselwa ukunyusela iPCB zinokuba ziindlela zobushushu ezisebenzayo kwisiseko senkqubo. Ukuqwalasela umphumo wokushisa ukushisa kunye neendleko, inani le-screws kufuneka libe lixabiso eliphezulu elifikelela kwindawo yokunciphisa imbuyekezo. Emva kokuba idityaniswe kwipleyiti ye-thermal conductive, ipleyiti yokuqinisa i-PCB yensimbi inendawo yokupholisa ngakumbi. Kwezinye izicelo apho i-PCB igutyungelwe ngeqokobhe, uhlobo olulawulwayo lwesixhobo sokulungisa i-welding inokusebenza okuphezulu kwe-thermal kuneqokobhe elipholileyo lomoya. Izisombululo zokupholisa, ezifana neefeni kunye neesinki zokushisa, nazo ziindlela eziqhelekileyo zokupholisa inkqubo, kodwa zihlala zifuna indawo eninzi okanye zifuna ukuguqula uyilo ukuze kuphuculwe umphumo wokupholisa.

Ukuyila inkqubo kunye nokusebenza okuphezulu kwe-thermal, akwanele ukukhetha isixhobo esihle se-IC kunye nesisombululo esivaliweyo. Ukusebenza kokutshatyalaliswa kobushushu kwe-IC kuxhomekeke kwi-PCB kunye nokukwazi kwenkqubo yokutshatyalaliswa kobushushu ukupholisa ngokukhawuleza izixhobo ze-IC. Ngokusebenzisa le ndlela yokupholisa i-passive engentla, ukusebenza kokutshatyalaliswa kobushushu kwenkqubo kunokuphuculwa kakhulu.