Metal fusion bonding – Process – Preplacing solid filler
Reexamination Certificate
1999-08-04
2001-02-27
Ryan, Patrick (Department: 1725)
Metal fusion bonding
Process
Preplacing solid filler
C228S223000, C228S253000, C228S180220
Reexamination Certificate
active
06193143
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a solder bump forming method for forming a solder bump by mounting a solder ball on an electrode, and a mounting apparatus and mounting method of solder ball.
BACKGROUND OF THE INVENTION
As a method of forming a solder bump on an electronic component, substrate or the like (hereinafter called a work), a method of using a solder ball is known. This method is to mount a solder ball on an electrode of a work, and heat to fuse the solder ball, thereby bonding the solder to the electrode. At the junction of the solder ball and electrode, in order to improve the bonding performance, a solder paste containing solder particles in the flux is applied. At this time, the methods of application include a method of applying a solder paste to the lower end of the solder ball preliminarily, and a method of transferring the solder paste by using a pin and applying on the electrode surface.
Depending on the type of the electronic component, a solder bump may be formed on a recess provided in an insulating layer covering the electrode such as TAB tape. In such a case, since the solder ball for forming a bump must be bonded with solder so as to be in conductive state with the electrode formed in the bottom of the recess, the solder paste must be applied in the inside of the recess.
However, since the solder paste is an adhesive paste material, it is not easy to fill in the recess uniformly. In particular, in the higher density trend of electronic components, since the aperture of recess is smaller than the diameter of the solder ball or the size of the transfer pin, it is more difficult to fill the recess with solder paste.
Sufficient filling with solder paste may be realized by a method of filling the recess with solder paste by printing by using a stencil mask, but this method requires a solder paste printing device, and the equipment cost is increased and the process is complicated, and it is hence not preferred. If attempted to bond with solder while filling with solder paste is insufficient, bonding with the electrode surface is defective, and a favorable solder bump is not formed.
SUMMARY OF THE INVENTION
It is hence an object of the invention to present a forming method of solder bump, and a mounting apparatus and a mounting method of solder ball, capable of filling with metal paste favorably without using exclusive metal paste printing device or the like, and forming a solder bump of high quality.
In the invention, a metal paste is applied on the solder ball lower side when putting the solder ball on the recess for forming a solder bump on the electrode in the bottom of the recess formed in the work, and by positioning this solder ball in the recess, the metal paste adhered to the solder ball is adhered to the top of the recess. Next, to fill the recess with the metal paste, for example, the solder ball is moved in the vertical direction to the recess, or moved in the horizontal direction, or moved in the combined motion. As a result, the metal paste adhered to the top of the recess can be pushed into the recess, so that the metal paste may be applied favorably.
A forming method of solder bump in a first aspect of the invention is a forming method of solder bump for forming a solder bump on the electrode in the bottom of a recess formed in a work, comprising a first step of adhering a metal paste to the lower side of a solder ball, a second step of adhering the metal paste adhered to the solder ball to the top of the recess by positioning the solder ball to the recess, a third step of performing at least one stroke of motion of moving the solder ball once away from the recess and bringing closer again, and a step of mounting the solder ball on the recess filled with the metal paste and heating to fuse the solder ball.
A forming method of solder bump in a second aspect of the invention relates to the forming method of solder bump in the first aspect of the invention, in which the third step includes a motion of moving the solder ball in the vertical direction to the work surface.
A forming method of solder bump in a third aspect of the invention relates to the forming method of solder bump in the first aspect of the invention, in which the third step includes a motion of moving the solder ball in the horizontal direction to the work surface.
A forming method of solder bump in a fourth aspect of the invention relates to the forming method of solder bump in the first aspect of the invention, in which the third step includes a motion of once moving the solder ball above the work surface, and then lowering to a position slightly remote from the center of the recess.
A forming method of solder bump in a fifth aspect of the invention is a forming method of solder bump for forming a solder bump on the electrode in the bottom of a recess formed in a work, comprising a first step of adhering a metal paste to the lower end of a pin by using a transfer pin, a second step of adhering the metal paste adhered to the transfer pin to the top of the recess by positioning the transfer pin at the recess, a third step of performing at least one stroke of motion of moving the transfer pin once away from the recess and bringing closer again, a step of mounting a solder ball on the recess filled with the metal paste, and a step of fusing the solder ball.
A forming method of solder bump in a sixth aspect of the invention relates to the forming method of solder bump in the fifth aspect of the invention, in which the third step includes a motion of moving the transfer pin in the vertical direction to the work surface.
A forming method of solder bump in a seventh aspect of the invention relates to the forming method of solder bump in the fifth aspect of the invention, in which the third step includes a motion of moving the transfer pin in the horizontal direction to the work surface.
A forming method of solder bump in an eighth aspect of the invention relates to the forming method of solder bump in the fifth aspect of the invention, in which the third step includes a motion of once moving transfer pin above the work surface, and then lowering to a position slightly remote from the center of the recess.
A forming method of solder bump in a ninth aspect of the invention is a forming method of solder bump for forming a solder bump on the electrode in the bottom of a recess formed in a work, comprising a first step of adhering a metal paste to the lower end of a transfer pin having the lower end of a smaller size than the opening size of the recess, a second step of adhering the metal paste adhered to the transfer pin to the electrode in the bottom of the recess by positioning the transfer pin in the recess, a fourth step of mounting a solder ball on the recess filled with the metal paste, and a fifth step of fusing the solder ball or metal paste.
A mounting apparatus of solder ball in a tenth aspect of the invention is for forming a solder bump on the electrode in the bottom of a recess formed in a work, being a mounting apparatus of solder ball for mounting a solder ball of a larger size than the opening size of this recess on the recess, comprising a work holder for holding the work with the recess forming side upward, a solder ball feeder for feeding the solder ball, a suction head for sucking and holding the solder ball in the solder ball feeder, a metal paste feeder having a device for straightening the liquid level of metal paste flat, suction head moving means for moving the suction head to suck the solder ball from the solder ball feeder, adhere the metal paste of the metal paste feeder to the lower side of the solder ball, and mount the solder ball coated with the metal paste on the recess of the work held in the work holder, and a controller for controlling the suction head moving means to perform at least one stroke of the motion of once moving the solder ball away from the recess in the mounting motion, and bringing closer again.
A mounting method of solder ball in an eleventh aspect of the invention is for forming a solder bump on the electrode in t
Johnson Jonathan
Matsushita Electric - Industrial Co., Ltd.
Ryan Patrick
Wenderoth , Lind & Ponack, L.L.P.
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