JPH11274239A - Producing method for electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for easily connecting a projecting solder electrode and a connecting electrode on a circuit board without using any flux for soldering. SOLUTION: An inter-metal compound 16 is formed between a solder and a thin sheet metal by heating and pressing the projecting solder electrode on an electronic component 11 onto the thin sheet metal on a substrate 15 for transfer, and the inter-metal compound 16 is transferred onto the thin sheet metal by releasing and removing the electronic component 11 from the substrate 15 for transfer. Thus, an intrinsic solder side is exposed by removing an oxidized film on the projecting solder electrode, and the electronic component 11 is soldered onto a circuit board 23 without using any solder flux. Besides, a resin sheet is used in place of the thin sheet metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electronic component for connecting a solder projection electrode of an electronic component having a solder projection electrode to a connection electrode on a circuit board.

[0002]

2. Description of the Related Art A face-down mounting method is known as a method for mounting electronic components on a circuit board at a high density without increasing the size of the mounted external components even for electronic components having a large number of input / output electrodes. ing. This face-down mounting method is a method of directly connecting a solder bump electrode two-dimensionally arranged on an electronic component and a connection electrode formed on a circuit board. In the face-down mounting method, a flux for improving solder wettability is used when a solder bump electrode is melted and soldered to a connection electrode on a circuit board. The flux improves the solder wettability by removing the oxide film on the solder surface and bringing the intrinsic surface of the solder into contact with the connection electrode. However, the use of flux usually produces flux residues. This flux residue is washed and removed after soldering in order to prevent corrosion and to seal the lower part of the electronic component with resin. The cleaning of the flux residue has a problem that the cost increases due to an increase in the number of steps such as cleaning and drying, and that the treatment of the cleaning liquid has a bad influence on the global environment. Due to this problem, development of a face-down mounting method that does not use flux has been required. As a method of removing the oxide film on the surface of the solder bump electrode without using a flux, a method of applying pressure to the semiconductor chip by applying ultrasonic waves to the semiconductor chip (Japanese Patent Laid-Open No. 63-288031) or a method of forming a small bump in the center of the bump electrode A method has been proposed in which the protruding electrode is pressure-bonded by deforming the protruding electrode by applying pressure while facing the connection electrode (Japanese Patent Laid-Open No. 2-112250). However, in the method of crimping the circuit board while applying ultrasonic waves, since ultrasonic waves are applied to the entire component, an ultrasonic vibrator having a large output is required, and the apparatus becomes large-scale, and as a result, cost is reduced. There is a problem that it leads to an increase and a problem that parts may be damaged by ultrasonic waves. In addition, the method of providing a small protrusion at the center of the protruding electrode and pressing the protruding electrode is to prevent the protruding electrode from being crushed,
Since the connection is performed at a temperature lower than the melting temperature of the protruding electrode, a large pressing force is required, so that the electronic components are easily damaged by the pressurization. Since it is impossible to form the protruding electrodes on the element portion, there is a problem that the number of protruding electrodes is limited and it is impossible to cope with the increase in the number of pins.

[0003]

As described above, as described above,
The method of crimping a circuit board while applying an ultrasonic wave has a problem that the device becomes large-scale, which leads to an increase in cost, and a problem that parts may be damaged by the ultrasonic wave. Further, the method of providing a small ridge at the center of the protruding electrode and performing pressure bonding has a problem that the electronic component is easily damaged and a problem that the number of protruding electrodes is limited and it is difficult to cope with the increase in the number of pins. The present invention has been made to solve the above problems, and has as its object to easily connect a solder bump electrode to a connection electrode on a circuit board without using a soldering flux.

[0004]

In order to achieve the above object, the present invention provides an electronic component having a plurality of solder bump electrodes whose surfaces are covered with an oxide film, and a transfer substrate having a metal surface. Opposing, pressing and heating the electronic component and the transfer substrate to form an intermetallic compound at the joint between the solder bump electrode and the metal surface; and transferring the electronic component to the transfer substrate. Transferring the intermetallic compound onto the metal surface by peeling and removing from the substrate, thereby removing at least a part of the oxide film on the surface of the solder bump electrode to expose the solder intrinsic surface; and Aligning a circuit board having a corresponding connection electrode with a solder bump electrode on the electronic component, and mounting the electronic component on the circuit board; and heating the electronic component and the circuit board to heat the electronic component and the circuit board. solder By melting the raised electrode,
Bonding the solder bump electrode and the connection electrode to each other. The present invention also provides a method for manufacturing an electronic component, wherein the metal surface is made of at least one of Au, Ni, Cu, In, and Sn.

Further, according to the present invention, the solder protruding electrodes may be made of Pb, S
Provided is a method for manufacturing an electronic component, which is an alloy made of at least one of n, Ag, Bi, Cu, and In.
The present invention also provides a method for manufacturing an electronic component, wherein a heating temperature in the step of forming the intermetallic compound is lower than a melting temperature of the solder bump electrode.

Further, the present invention provides a method in which an electronic component having a plurality of solder projecting electrodes whose surfaces are covered with an oxide film is opposed to a resin sheet, and the electronic component and the resin sheet are pressed and heated. Embedding the solder projecting electrode in the resin sheet; heating the electronic component in a non-oxidizing atmosphere to melt the solder projecting electrode; Removing the electronic component from the resin sheet while maintaining the molten state, removing the oxide film on the surface of the solder bump electrode by transferring it to the resin sheet, exposing a solder intrinsic surface, Aligning the solder bump electrode on the circuit board with the circuit board having the connection electrode corresponding to the solder bump electrode, and mounting the electronic component on the circuit board; Bonding the solder projection electrode and the connection electrode by heating the electronic component and the circuit board to melt the solder projection electrode. provide.

The present invention also provides a method for manufacturing an electronic component, wherein the resin sheet is made of a thermoplastic resin. The present invention also provides a method for manufacturing an electronic component, wherein the heating temperature in the step of embedding the semiconductor bump electrode in the resin sheet is higher than the softening temperature of the resin sheet and lower than the melting temperature of the solder bump electrode. .

In the present invention, the solder bump electrode on the electronic component is heated and pressed against the metal thin film on the transfer substrate to form an intermetallic compound between the solder and the metal thin film, and the electronic component is peeled off from the transfer substrate. To transfer the intermetallic compound onto the metal thin film.
By doing so, the oxide film on the solder bump electrode is removed to expose the intrinsic surface of the solder. Next, by mounting this electronic component on a circuit board and melting the solder bump electrodes, soldering can be performed without using flux.

In this method, an oxide film exists on the surface of the solder bump electrode, but the reactivity between the solder bump electrode and the metal thin film is improved by heating, so that an intermetallic compound is formed at the interface therebetween. Furthermore, the stress at the time of peeling the electronic component is concentrated on the joint between the solder bump electrode and the metal thin film, and the breaking strength of the solder bump electrode material is smaller than the breaking strength of the intermetallic compound. Occurs inside the solder. As a result, the intrinsic surface of the solder is exposed, and the surface of the solder bump electrode having no wettability and having no oxide film can be obtained.

Further, according to the present invention, a solder bump electrode on an electronic component is embedded in a resin sheet, and the electronic component is removed from the resin sheet in a non-oxidizing atmosphere while melting the solder bump electrode. By doing so, the surface oxide film of the solder bump electrode is transferred and removed to the resin sheet to expose the intrinsic surface of the solder. Next, the electronic component is mounted on a circuit board and the solder bump electrodes are melted, so that soldering can be performed without using flux.

In this method, an oxide film is present on the surface of the solder bump electrode, but since the solder oxide film has a high melting point,
When the electronic component is removed from the resin sheet in a state where the solder bump electrode is melted, the solder oxide film is transferred while being fixed to the resin sheet, so that the intrinsic surface of the solder is exposed, and there is no oxide film and good wettability. A solder bump electrode surface is obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing an electronic component according to the present invention will be described with reference to FIGS. First, as shown in FIG. 1, an electronic component 11 composed of a silicon semiconductor chip having a solder bump electrode 12 formed on the surface, and a metal film 14 formed on the surface.
The transfer substrate 15 made of quartz glass on which is formed is opposed to each other. The electronic component 11 is a diced silicon semiconductor chip having a size of 4.3 mm × 4.1 mm.
Are formed around the solder bump electrodes 12 made of Sn / Pb (60% / 40% weight ratio) alloy at a pitch of 250 microns in a row. The solder bump electrode 12 has a spherical shape with a diameter of 100 μm and a height of 60 μm. On the surface of the solder bump electrode 12, an oxide film 13 made of tin oxide and having a thickness of 5 nm to 50 nm is formed. Ti / N on transfer substrate 15
A metal thin film 14 in which i / Au is sequentially laminated at a thickness of 100 nm / 500 nm / 100 nm is formed on the entire surface. Next, as shown in FIG. 2, pressure and temperature are applied to the electronic component 11 and the transfer substrate 15 to form an intermetallic compound 16 at a joint between the solder bump electrode 12 and the metal thin film 14. In this step,
Sn contained in the solder bump electrode 12 and Au in the uppermost layer of the metal thin film 14 have high reactivity, and rapidly form an intermetallic compound layer 16 mainly composed of AuSn2 at a high temperature. The heating temperature in this step is lower than the melting temperature of the solder bump electrode 12, and the temperature is 10
0 ° C to 150 ° C, heating time is 10 seconds to 60 seconds.
The pressure in this step is 10 MPa to 200 MPa. By this step, the thickness of the intermetallic compound layer 16 formed is
60 nm to 300 nm. At this time, in order to prevent the melting of the metal thin film 14 into the solder bump electrodes 12, the heating temperature in this step is set to be lower than the melting temperature of the solder bump electrodes 12 (183 ° C.).
Next, as shown in FIG. 3, the electronic component 11 is transferred to the transfer substrate 1.
5 to remove the intermetallic compound layer 16 from the metal thin film 14.
Transfer to the top. In this step, the oxide film on the surface of the solder bump electrode 12 is partially removed to expose the solder intrinsic surface 17. At this time, since the joint between the solder bump electrode 12 and the metal thin film 14 is narrowed, the stress at the time of peeling the electronic component 11 concentrates on the joint between the solder bump electrode 12 and the metal thin film 14. The breaking strength (40 MPa to 80 MPa) of the solder bump electrode 12 (SnPb (40/60)) is determined by the intermetallic compound layer 16 (AnSn2
) Is smaller than the breaking strength (100 MPa to 250 MPa). Above 2
For the following two reasons, the fracture at the time of peeling is caused by the intermetallic compound layer 16.
At the interface between the solder bump electrodes 12 (inside the solder bump electrodes). Thus, the solder intrinsic surface is exposed, and the surface of the solder bump electrode 12 having good wettability is obtained.

Next, as shown in FIG. 4, a circuit board 23 made of glass epoxy having a connection electrode 22 on which copper / nickel / gold is sequentially laminated on the surface and a solder bump electrode 12 having an intrinsic surface are located. At the same time, the electronic component 11 is mounted. By applying a pressure of 5MPa to 20MPa when mounting, the connection electrode and the solder intrinsic surface are brought into close contact. The circuit board 23 used at this time is not limited to glass = epoxy, but may be BT resin / polyphenylethylene / alumina / aluminum nitride. Next, as shown in FIG. 5, the electronic component 11 and the circuit board 23 are heated to melt the solder bump electrodes 12, thereby joining the electronic component to the circuit board. Use a belt-type heating furnace for heating.
Heat at 260 ° C for 10 to 90 seconds. This heating
In order to prevent the solder intrinsic surface from being oxidized during heating, the soldering is performed in a non-oxidizing atmosphere composed of nitrogen or a mixed gas of nitrogen and hydrogen. In this melting step, since the intrinsic surface of the solder bump electrode 12 and the connection electrode 22 are in direct contact with each other without the intermediary of the solder oxide film, as soon as the solder is melted, Au on the surface of the connection electrode 22 melts into the solder bump electrode 12. A uniform intermetallic compound (NiSn ₂ ) layer is formed between the exposed Ni and the solder, and the solder and the connection electrode are wetted to form a strong joint.

Through the above steps, the electronic component 11 and the connection electrode 22 on the circuit board 23 can be soldered without using a flux. FIG. 6 is a process chart showing another embodiment of the present invention. First, as shown in FIG. 6A, a pressure and a temperature are applied to the electronic component 11 in advance on the transfer substrate 15 by using the heating head 21, and the intermetallic compound is applied to the joint between the solder bump electrode and the metal thin film. Are formed so as to form. At this time, a plurality of sheets with electronic chips as shown in FIG. 6B are prepared. Next, FIG.
As shown in FIG. 3C, the oxide film on the solder bump electrode is removed by transferring the intermetallic compound layer 16 onto the metal thin film by peeling and removing the electronic component from the transfer substrate using the suction head 25. To expose the intrinsic surface of the solder.

Next, as shown in FIG. 6D, the circuit board 23 having the connection electrode 22 and the solder bump electrode on the electronic component are aligned and mounted. Finally, as shown in FIG. 6E, the electronic component is joined to the circuit board by heating the electronic component and the circuit board to melt the solder bump electrodes.

The steps shown in FIG. 6C to FIG. 6E are performed continuously to prevent re-oxidation of the solder intrinsic surface exposed in the step shown in FIG. It is possible to obtain a solder joint having high property. By preparing a large number of sheets with electronic chips shown in FIG. 6B,
Work efficiency is significantly improved. The material of the solder bump electrode of this embodiment is not limited to Sn / Pb alloy, but may be Pb, Sn, A
An alloy formed by combining any of g, Bi, Cu, and In may be used. Further, the metal thin film of the present embodiment is not limited to the Ti / Ni / Au laminated film, but includes a Ti / Ni thin film, a Ti / Cu thin film, a Ti / Cu / Au thin film, an In coating film on a Cu foil electrode, A Sn coating film on a foil electrode or the like may be used. Further, the transfer substrate of this embodiment is not limited to quartz glass, but may be soda glass or silicon. In addition, instead of the combination of metal thin film and transfer substrate, Cu
Plates, Ni plates, Au-coated Cu plates, and Au-coated Ni plates may be used.

Next, another embodiment of the method for manufacturing an electronic component according to the present invention will be described. First, as shown in FIG. 7, an electronic component 11 made of a silicon semiconductor chip having solder bump electrodes 12 formed on a surface thereof and a resin sheet 31 made of a thermoplastic resin
Face each other. This electronic component 11 measures 4.3 mm x 4.
1mm silicon semiconductor chip diced.
Around this electronic component 11, 64 solder bump electrodes 12 made of a Sn / Pb (60% / 40% weight ratio) alloy are formed in a row at a pitch of 250 microns. The surface of the solder bump electrode 12 is covered with an oxide film 13. Resin sheet 3
As the thermoplastic resin used in No. 1, a polyacetal resin having a softening temperature below the solder melting temperature (softening temperature: 80 to 1)
60 ° C.), polyamide resin (softening temperature: 80 to 230)
C), polysulfone resin (softening temperature: 150-220)
℃), polyether sulfone resin (softening temperature: 150 ~
220 ° C), polycarbonate resin (softening temperature: 100
-150 ° C), polybutylene terephthalate resin (softening temperature: 80-210 ° C), polyetherketone resin (softening temperature: 150-280 ° C), polyetheretherketone resin (softening temperature: 150-280 ° C), polyether Imide resin (softening temperature: 200 to 210 ° C), polyarylate resin (softening temperature: 50 to 120 ° C), polyethylene terephthalate resin (softening temperature: 180 to 230)
° C), polyphenylene sulfide resin (softening temperature: 1
60-280 ° C.).

Next, as shown in FIG. 8, a pressure of 5 Pa to 100 Pa is applied to the electronic component 11 and the resin sheet 31.
A temperature of 0 ° C. to 150 ° C.
Is embedded in the resin sheet 31. By setting the heating temperature in this step to be equal to or lower than the melting temperature of the solder and equal to or higher than the softening temperature of the resin sheet, the resin sheet is softened, while the solder bump electrodes do not soften. The electrodes are completely embedded in the resin sheet. Next, as shown in FIG. 9, the electronic component 11 is heated to melt the solder bump electrodes 12, and the electronic component 11 is sucked using a suction head and peeled off from the resin sheet 32. In this step, the surface oxide film 13 of the solder bump electrode 12 is removed by being transferred to the resin sheet 31 to expose the intrinsic solder surface. This step is performed in a non-oxidizing atmosphere such as nitrogen or argon to prevent re-oxidation of the solder surface. In this step, since the melting point of the oxide film 13 on the surface of the solder bump electrode 12 is as high as 1127 ° C., only the solder is melted. Therefore, the oxide film is transferred to the resin sheet side, and the intrinsic surface of the solder is exposed.

Next, as shown in FIG.
The circuit board 23 having the solder bump electrodes 12 on the electronic component 11 is aligned and mounted. A circuit board similar to that of the first embodiment is used.

Finally, as shown in FIG.
The electronic component 11 is joined to the circuit board 23 by heating the circuit board 1 and the circuit board 23 to melt the solder bump electrodes. The same joining conditions as in the first embodiment are used. According to the above method, means for connecting the solder bump electrode and the connection electrode on the circuit board without using a soldering flux is provided.

[0021]

As described above, according to the method of manufacturing an electronic component of the present invention, it is possible to form a joint using a solder bump electrode without using a soldering flux.

[Brief description of the drawings]

FIG. 1 is a process chart showing a first embodiment of the present invention.

FIG. 2 is a process chart showing a first embodiment of the present invention.

FIG. 3 is a process chart showing a first embodiment of the present invention.

FIG. 4 is a process chart showing a first embodiment of the present invention.

FIG. 5 is a process chart showing a first embodiment of the present invention.

FIG. 6 is a process chart showing a second embodiment of the present invention.

FIG. 7 is a process chart showing a third embodiment of the present invention.

FIG. 8 is a process chart showing a third embodiment of the present invention.

FIG. 9 is a process chart showing a third embodiment of the present invention.

FIG. 10 is a process chart showing a third embodiment of the present invention.

FIG. 11 is a process chart showing a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Electronic component 12 Solder projection electrode 13 Oxide film 14 Metal thin film 15 Transfer substrate 16 Intermetallic compound 17 Solder intrinsic surface 21 Heating head 22 Connection electrode 23 Circuit board 25 Suction head 31 Resin sheet

Claims (7)

[Claims] An electronic component having a plurality of solder bump electrodes, the surface of which is covered with an oxide film, and a transfer substrate having a metal surface are opposed to each other, and the electronic component and the transfer substrate are pressed. Forming an intermetallic compound at the joint between the solder bump electrode and the metal surface by heating; and removing the electronic component from the transfer substrate to remove the intermetallic compound on the metal surface. Transferring at least a portion of the oxide film on the surface of the solder bump electrode to expose the intrinsic surface of the solder, and a circuit board having connection electrodes corresponding to the solder bump electrode and solder on the electronic component. Positioning the protruding electrode and mounting the electronic component on the circuit board; heating the electronic component and the circuit board to melt the solder protruding electrode; Electronic component manufacturing method characterized by comprising the step of bonding the connection electrodes. 2. The method according to claim 1, wherein the metal surface is made of at least one of Au, Ni, Cu, In, and Sn. 3. The solder bump electrode includes Pb, Sn, Ag, Bi, Cu,
2. The method for manufacturing an electronic component according to claim 1, wherein the alloy is an alloy comprising at least one of In. 4. The method according to claim 1, wherein a heating temperature in the step of forming the intermetallic compound is lower than a melting temperature of the solder bump electrode. 5. An electronic component having a plurality of solder projecting electrodes, the surface of which is covered with an oxide film, and a resin sheet are opposed to each other, and the electronic component and the resin sheet are pressurized and heated. A step of embedding the projecting electrode in the resin sheet; a step of heating the electronic component in a non-oxidizing atmosphere to melt the solder projecting electrode; and a step of melting the solder projecting electrode in a non-oxidizing atmosphere. Removing the electronic component from the resin sheet while maintaining the state, thereby removing an oxide film on the surface of the solder bump electrode by transferring it to the resin sheet to expose a solder intrinsic surface; Positioning a circuit board having connection electrodes corresponding to the electrodes and the solder bump electrodes on the electronic component, and mounting the electronic component on the circuit board; Bonding the solder protrusion electrode and the connection electrode by heating the product and the circuit board to melt the solder protrusion electrode. 6. The method according to claim 5, wherein the resin sheet is made of a thermoplastic resin. 7. The electronic component according to claim 5, wherein the heating temperature in the step of embedding the semiconductor projecting electrode in the resin sheet is higher than the softening temperature of the resin sheet and lower than the melting temperature of the solder projecting electrode. Production method.