JPH11135934A - Bare ic and smd mixed mounting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mount a surface mounting method part and a bare IC parallel in the same process line, utilizing laser ablation two processes for supplying a junction material to an electrode pad of a terminal electrode of a bare IC and supplying a sealing material to a part including a bare IC and a circuit board. SOLUTION: A terminal electrodes 4 and 4' are laminated on a circuit board 5. Eutectic solder 7 is supplied to a junction part of an electrode 9 of a surface mounted device(SMD) 6. Although the eutectic solder 7 is used as a junction material in the method, lead-free solder can be also used. Meanwhile, a junction material consisting of alloy of two or more kinds of metals is supplied on the electrode pad 2 of an electrode terminal of a bare IC by a laser ablasion method, and a bump electrode 3 is formed. After the bump electrode 3 and the terminal electrode 4 are joined, a sealing material is supplied to a part including the bare IC 1. for total resin sealing as shown in a resin sealing layer 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting a semiconductor device in which a bare IC and a surface mount type component (hereinafter referred to as SMD) are mixedly mounted on a circuit board.

[0002]

2. Description of the Related Art Conventionally, in a mounting method in which a bare IC and an SMD are mixedly mounted on a substrate, a surface mounting step (hereinafter, referred to as an SMT step) of mounting the SMD is performed after a semiconductor mounting step of mounting the bare IC. Was. In the semiconductor mounting process, the bump electrode provided on the electrode pad of the bare IC is electrically connected to the terminal electrode on the circuit board by a conductive adhesive containing fine powder of an alloy of two or more metals as a conductive filler. I was connected. The connection required more than two hours. Also, the electrically connected bump electrodes and the terminal electrodes on the circuit board are resin-sealed using an epoxy-based sealing material. Two to four hours were required for the resin sealing.

[0003]

As described above, the connection of the bump electrode of the conventional bare IC to the terminal electrode on the circuit board is as follows.
It took a long time to seal the bare IC connected to the circuit board with resin. For this reason, the above steps of the semiconductor mounting step could not be matched because the tact time was too different from that of the SMT step in which the line tact was within 1 minute. Therefore,
It has been difficult to mount the bare IC and the SMD in parallel on the circuit board in the same process line flow. Therefore, there has been a demand for a mounting method capable of performing the semiconductor mounting process and the SMT process in parallel in the same process line flow. An object of the present invention is to solve such a problem and to provide a method of mounting a bare IC and an SMD in which a semiconductor mounting process and an SMT process can be performed in the same process line flow.

[0004]

SUMMARY OF THE INVENTION The bare IC and S according to the present invention are provided.
The MD mounting method is a method for mounting a semiconductor device in which a bare IC and an SMD are mounted on a circuit board. Supplying a bonding material comprising an alloy of two or more metals by a method to form a bump and performing flux spray on the bump;
Mounting the SMD and the bare IC on terminal electrodes of a circuit board, performing reflow soldering on the circuit board on which the SMD and the bare IC are mounted, and joining the SMD electrodes to the circuit board; And a step of joining the bump to a terminal electrode of the circuit board, and a step of supplying a sealing material to a portion including the bump and the circuit board by a laser ablation method to perform resin sealing on the entire surface. Here, the laser ablation method is to excite interatomic bonds or intermolecular bonds by the energy of a laser to cut the bonds, and to apply the cut atoms or atomic groups or molecules or molecular groups to an object by laser energy. Means a processing method that is transferred to and supplied to According to the present invention, by using the laser ablation method, the bare IC and the SMD can be mounted in parallel on the circuit board in the same process line flow.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. << Embodiment >> Bare I of a semiconductor device in an embodiment of the present invention
The C and SMD mixed mounting method will be described with reference to FIGS. FIG. 1 shows a bare IC and an SMD according to the present invention.
FIG. 4 is a cross-sectional view of a circuit board before mounting and sealing by a mixed mounting method. FIG. 2 is a cross-sectional view of the circuit board after being mounted and sealed by the mixed mounting method of bare IC and SMD according to the present invention. The circuit board before sealing shown in FIG. 1 includes a circuit board 5, terminal electrodes 4 and 4 ′ provided on the circuit board 5, electrode pads 2 provided on the lower surface of the bare IC 1,
A eutectic solder 7 is provided as a bonding solder provided at a bonding portion between the bump electrode 3 provided on the electrode pad 2 and the electrode 9 of the SMD 6. A bump electrode 3 is formed on the terminal electrode 4 by a laser.
An electrode 9 of SMD 6 is joined by eutectic solder 7 on another terminal electrode 4 ′. The circuit board after sealing shown in FIG. 2 includes, in addition to the components shown in FIG. 1, a bare IC 1, an electrode pad 2 on the lower surface thereof, and a resin sealing layer 8 for sealing the bump electrodes 3. .

Hereinafter, a method for mounting a bare IC and an SMD on a circuit board will be described. Terminal electrodes 4 and 4 ′ are laminated on the circuit board 5 by a known method using a metal mask. For the joint portion of the electrode 9 of the SMD 6,
The eutectic solder 7 is supplied by a known printing method using a metal mask. In the present embodiment, the eutectic solder 7 is used as a joining material, but a lead-free solder can also be used. On the other hand, a bonding material composed of an alloy of two or more metals is supplied onto the electrode pads 2 of the terminal electrodes of the bare IC 1 by a laser ablation method to form bump electrodes 3.
To form

[0007] As an optimal embodiment of the manufacturing process of the bump electrode 3, first, an alloy of Sn and Ag (for example, Sn
Is 96.5 wt%, Ag is 3.5 wt%), Sn and B
i alloy (for example, Sn is 42 wt%, Bi is 58 wt%)
%) On a Teflon sheet so as to have a thickness of 10 μm to 30 μm so that a material sheet is prepared. The electrode pad 2 of the bare IC 1 and the material sheet are kept at a distance of about 0.1 mm, and a laser output of 0.15 w, an irradiation time of 0.1 second, and a spot are applied to the surface of the material sheet opposite to the bare IC 1. An excimer laser having a diameter of 50 μm is irradiated. By this irradiation, the alloy deposited on the material sheet is ablated, and the bump electrode 3 is formed on the terminal electrode 2. In addition to the above materials, an alloy based on a metal group consisting of Sn and In, Sn and Bi, Sn and Ag, Sn-Ag
-Bi-based alloy (Sn: 83-92 wt%, Ag: 2.5
~ 4.0wt%, Bi is 5 ~ 18wt%), Sn-Ag
-Bi-In-Cu-based alloy (Sn is 80 to 92 wt%,
Ag is 2.5-4.0 wt%, Bi is 5-18 wt%,
In is 0.1 to 1.5 wt%, Cu is 0.1 to 0.7 w
t%) can also be used.

[0008] Flux spraying is performed on the soldered portions of the bump electrode 3 and the SMD 6. After that, SM
D 6 and the bare IC 1 are mounted on the circuit board 5.
After the SMD 6 and the bare IC 1 are mounted, the SMD
In a preferred embodiment, a reflow soldering process is performed on the part including the bare IC 6 and the bare IC 1 in the air having a peak temperature of 250 ° C. to 260 ° C. for about 1 minute. By this processing, the electrode 9 of the SMD 6 is electrically and mechanically connected to the circuit board 5, and the bump electrode 3 of the bare IC 1 is electrically and mechanically connected to the terminal electrode 4 on the circuit board 5. Perform bonding. In addition,
Instead of performing the reflow soldering process in the air, the reflow soldering process may be performed in an inert gas such as nitrogen or a reducing gas such as hydrogen. After the bump electrode 3 and the terminal electrode 4 are electrically and mechanically joined, a sealing material is supplied to a portion including the bare IC 1 by a laser ablation method, and as shown in a resin sealing layer 8 in FIG. The entire surface is resin-sealed.

In the above-described process of forming the resin sealing layer 8, the laser
An optimal embodiment by the ablation method will be described. First,
A Teflon sheet is coated with polyethylene as a sealing material to a thickness of 0.5 to 1.0 mm to produce a material sheet. Next, the material sheet is held on the bare IC 1 at an interval of about 3 mm, and the bare IC 1 of the material sheet is held.
From the side opposite to the side facing
YAG laser irradiation with mw, irradiation time of 60 seconds and spot diameter of 50 μm is performed. As a result of this irradiation, the polyethylene applied to the material sheet is ablated and the entire surface of the bare IC 1 is sealed with resin. As the material to be applied to the Teflon sheet, polypropylene, polyamide or polycarbonate can be used in addition to polyethylene. In these cases, resin sealing by laser ablation can be performed under the same irradiation conditions.

[0010] In the present invention, as shown in the above embodiment, by using the laser ablation method, the bare I
The time required for supplying the bonding material from the material sheet to the electrode pad 2 of C1 and forming the bump electrode 3 is less than 3 minutes. Furthermore, the time required to supply and seal a sealing material for sealing the barely bonded bare IC 1 by performing the reflow soldering process is less than one minute. As a result, it is possible to mount the SMD 6 on the circuit board, which requires only about 1 minute, and to form the bump electrode 3 in about 3 minutes, and to seal the bare IC portion with the resin in about 1 minute. Both the mounting of the bare IC 1 and the mounting of the bare IC 1 on the circuit board 5 can be performed smoothly in parallel in the flow of the same process line without a large excess or shortage of time.

[0011]

As described above, in the semiconductor mounting process,
Two steps of a step of supplying a bonding material to the electrode pad of the terminal electrode of the bare IC to form a bump, and a step of supplying a sealing material to a portion including the bare IC and the circuit board to resin-encapsulate the entire surface. In addition, by using the laser ablation method, it is possible to mount the SMD and bare IC in parallel in the same process line by newly incorporating only the equipment used for the laser ablation method. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a circuit board before being sealed and mounted by a bare IC and SMD mixed mounting method according to the present invention.

FIG. 2 is a cross-sectional view of a circuit board after being mounted and sealed by a mixed mounting method of a bare IC and an SMD according to the present invention.

[Description of Signs] 1 Bare IC 2 Electrode pad 3 Bump electrode 4 Terminal electrode 5 Circuit board 6 SMD 7 Eutectic solder 8 Resin sealing layer

Claims (4)

[Claims] 1. A mounting method of a semiconductor device for mounting a bare IC and an SMD on a circuit board, wherein a bonding material is supplied to an electrode of the SMD, and a laser ablation method is applied to an electrode pad of a terminal electrode of the bare IC. Supplying a bonding material composed of an alloy of two or more metals to form a bump and performing flux spray on the bump; mounting the SMD and the bare IC on a terminal electrode of a circuit board; Performing a reflow soldering process on the circuit board on which the SMD and the bare IC are mounted, joining the electrodes of the SMD to the circuit board, and joining the bumps to terminal electrodes of the circuit board; and Supplying a sealing material to a portion including the bump and the circuit board by a laser ablation method to perform resin sealing on the entire surface. Bear IC and SMD hybrid implementation. 2. An alloy of two or more metals, wherein Sn and I
n, Sn and Bi, and an alloy based on a metal group selected from the group consisting of Sn and Ag. In the case of a Sn-Ag-Bi alloy, Sn is 83 to 92 wt% and Ag is 2.5 to 4.
0 wt%, Bi is 5 to 18 wt%, and Sn-Ag-
In the case of Bi-In-Cu alloy, Sn is 80-92 wt.
%, Ag is 2.5 to 4.0 wt%, Bi is 5 to 18 wt%
%, 0.1 to 1.5 wt% of In, and 0.1 to 0.1 wt% of Cu.
The bare IC and the SM according to claim 1, wherein the content is 7 wt%.
D Mixed mounting method. 3. The bare IC and SM according to claim 1, wherein the sealing material is polyethylene, polypropylene, polyamide, or polycarbonate.
D Mixed mounting method. 4. The bare IC and SM according to claim 1, wherein the reflow soldering is performed in an inert gas or a reducing gas.
D Mixed mounting method.