1. Technical Field
The present invention relates to a method of welding electronic components, and especially to a method of welding electronic components onto printed circuit boards (PCBs).
2. Discussion of Related Art
Recently, as the electronic appliances are becoming smaller in size and diversified in function, printed circuit boards (PCBs) widely used in such electronic appliances which are required to have high circuit density and reliability.
Usually, a number of electronic components, such as resistors and capacitors, are mounted on PCBs. Surface mounting technology (SMT) is widely used in packaging such electronic components onto PCBs. Generally, in a packaging process, PCBs are placed on a metal tray, solder pastes are applied on welding pads of the PCBs, electronic components are disposed on the welding pads, and the solder pastes are heated and melted in an oven thereby welding the electronic components on the welding pads of the PCBs. The metal tray is usually made of metal; therefore, the metal tray will absorb heat in the oven and solder pastes may be inefficiently heated, resulting in defective welding joint.
Therefore, there is a desire to develop a method of welding electronic components on PCBs, in which the solder pastes are fully melted; thereby a better welding result is obtained.
An exemplary method of welding electronic components on PCBs is disclosed. Firstly, a metal tray including a number of supporting areas is provided. At least one through hole is formed in each of the supporting areas. Secondly, solder pastes are applied onto welding pads of PCBs. Thirdly, electronic components are mounted on the welding pads. Fourthly, PCBs are placed on the metal tray in a manner that each printed circuit board is placed in a corresponding supporting area and the welding pads being above the through hole. Finally, the solder pastes are heated to weld the electronic components on the printed circuit board.
This and other features and advantages of the present invention as well as the preferred embodiments thereof and a method of welding electronic components on PCBs in accordance with the invention will become apparent from the following detailed description and the descriptions of the drawings.
Many aspects of the present invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present invention.
Referring to
Referring to
The metal tray 100 and the PCBs 200 disposed on the metal tray 100 are placed in an oven so as to heat the solder paste 24. The solder paste 24 is then melted and the electronic components 26 are bonded to the welding pads 22 respectively.
In the metal tray 100, a through hole 14 is defined in each of the supporting area 12, however, it is to be understood that more than one through hole can also be defined in each of the supporting area 12.
In the metal tray 300 and 400, when a PCB is disposed in a corresponding supporting area 32 thereof, the PCB corresponds to four or more through holes 25. When the metal tray 200 and 300 are disposed in an oven, heat can reach the PCB directly through the through holes 25, thus the solder paste can be sufficiently melted.
Finally, it is to be understood that the above-described embodiments are intended to illustrate rather than limit the invention. Variations may be made to the embodiments without departing from the spirit of the invention as claimed. The above-described embodiments illustrate the scope of the invention but do not restrict the scope of the invention.
Number | Date | Country | Kind |
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200710076568.1 | Aug 2007 | CN | national |