JP2001007158A - Solder bump joining method and solder bump joined body - Google Patents

Abstract

[PROBLEMS] To provide a solder bump bonding method capable of realizing high reliability even when a fine semiconductor chip is flip-chip bonded. An electrode formed on a first substrate is provided.
And a method of joining solder bumps to join the solder bumps 18 formed on the second substrate 20, wherein a bonding aid 14 containing alcohol or carboxylic acid is applied to the electrodes, A step of bonding the solder bumps to the electrodes using a bonding aid while melting the solder bumps, and injecting a thermosetting resin 22 between the first substrate and the second substrate while leaving the bonding aids And a step of heating the thermosetting resin so that the thermosetting resin is cured while dissolving the bonding aid in the thermosetting resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder bump joining method and a solder bump joined body joined by using the same, and more particularly, to a solder bump joining method capable of improving reliability and joined by using the same. The present invention relates to a solder bump assembly.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices become smaller and lighter, semiconductor chips are mounted face down on circuit boards.
Attention has been focused on flip chip mounting technology. The flip-chip bonding technology allows a plurality of semiconductor chips to be spread over a circuit board and enables almost ideal high-density mounting. Adopted in the field. In addition, flip-chip mounting technology can realize multi-terminal semiconductor chips and can reduce wiring delay as compared with the wire bonding method. Therefore, flip-chip mounting technology has recently been adopted in the packaging of a single semiconductor chip. .

In flip-chip bonding, solder bumps are formed on electrodes on the semiconductor chip side in advance, the solder bumps are aligned with electrodes formed on the circuit board side, and then the soldering is performed by heating. Done. When soldering is performed, a flux made of rosin or the like is applied to the electrode on the circuit board side in order to secure metallic wetness between the solder and the electrode, and this flux is washed after the soldering.

However, with the integration of semiconductor chips,
The number of pins of a semiconductor chip tends to increase, and the pitch at which solder bumps are formed tends to be narrow. For this reason, recently, it has become difficult to wash the flux after soldering.

Accordingly, a technique for performing flip chip bonding without using flux has been proposed. For example,
Japanese Patent Application Laid-Open No. 4-83353 discloses a technique for performing flip-chip bonding by hot pressing in a reducing atmosphere. According to this technique, a flux is not required at the time of bonding, so that it is possible to apply flip-chip bonding even to a fine semiconductor chip for which cleaning of the flux is difficult.

However, when performing flip-chip bonding in a reducing atmosphere, a heated hydrogen atmosphere is used as the reducing atmosphere. The heated hydrogen atmosphere is dangerous in handling and requires expensive equipment and the like, so that high cost is required for safety measures of the equipment and operation costs. Moreover, in order to obtain a sufficient reducing effect, the hydrogen reducing atmosphere must be heated to 300 ° C. or higher. In this case, an inexpensive resin substrate cannot be used because of its low heat resistance.

Therefore, as a technique for performing flip-chip joining without using a hydrogen-reducing atmosphere or rosin-based flux, a technique using volatile alcohol as a joining aid has been proposed. For example, JP-A-6-41601
In the technology disclosed in Japanese Patent Application Laid-Open No. 7-58150, soldering is performed using a bonding aid made of glycol or a derivative thereof having a higher boiling point than the melting point of the solder, and thereafter, the soldering point is higher than the boiling point of the bonding aid. To evaporate the bonding aid. By using such a technique, the bonding assistant can be volatilized by heating it to a temperature equal to or higher than the boiling point of the bonding assistant, so that flip chip bonding can be performed without using a hydrogen reducing atmosphere or rosin-based flux.

[0008]

However, in the flip-chip bonding technique proposed in Japanese Patent Application Laid-Open No. 6-41601, the material of the solder bump has a melting point of 183.
° C Sn-37Pb is used, and diethylene glycol monoethyl ether having a boiling point of 210 ° C is used as a bonding aid. Also, Japanese Patent Application Laid-Open No. 7-5815
In the flip chip bonding technology proposed in Japanese Patent Publication No.
As a material for the solder bump, Sn-95 having a melting point of 300 ° C.
Pb is used and has a boiling point of about 300 as a bonding aid.
Hexanetriol, which is considered to be in ° C, is used.
In such flip chip bonding technology, the temperature difference between the melting point of the solder bumps and the boiling point of the bonding aid is small, so that when the solder bumps are melted, the bonding aid volatilizes,
It is difficult to ensure sufficient wetting. If a bonding aid with a sufficiently high boiling point relative to the melting point of the solder is used, it is possible to ensure sufficient wetting, but in this case, it is necessary to heat at a high temperature when evaporating the bonding aid. In addition, the diffusion reaction between the solder and the electrode proceeds during the heating, and the bonding portion may be weakened, which may lower the reliability.

An object of the present invention is to provide a solder bump bonding method capable of realizing high reliability even when a fine semiconductor chip is flip-chip bonded, and a solder bump bonded body bonded by using the method. To provide.

[0010]

In recent years, in flip-chip bonding technology, an underfill technique of filling an epoxy resin or the like between a semiconductor chip and a circuit board has attracted attention. It is disclosed in gazettes and the like.

In the underfill technique, after a semiconductor chip and a circuit board are flip-chip bonded, a thermosetting resin such as an epoxy resin is injected between the semiconductor chip and the circuit board, and then heated to be thermoset. Cure the resin. Since the cured thermosetting resin is filled between the semiconductor chip and the circuit board, the thermal expansion distortion between the semiconductor chip and the circuit board can be reduced, thereby improving the reliability of the joint. can do. Further, since the space between the semiconductor chip and the circuit board is filled with a thermosetting resin, it is possible to prevent corrosion of the solder bumps and electrodes due to intrusion of moisture, and to suppress migration and the like. Is also possible.

In order to reduce thermal expansion distortion, prevent intrusion of moisture, and suppress migration by using an underfill technique, the adhesiveness between the thermosetting resin and the semiconductor chip, the thermosetting resin and the circuit It is considered necessary to ensure sufficient adhesion to the substrate. In order to secure the adhesion between the thermosetting resin and the semiconductor chip and the adhesion between the thermosetting resin and the circuit board, it is considered that it is not desirable that the residue of the bonding aid remains, Conventionally, after the solder bonding, cleaning of the bonding aid and the like have been performed. For example,
In the technique disclosed in JP-A-63-31647, soldering is performed using a bonding aid composed of rosin flux, and then the bonding aid is washed with a solvent.

The inventors of the present application have conducted intensive studies, and as a result,
By dissolving the bonding aid in the thermosetting resin without having to clean the bonding aid, the adhesion between the thermosetting resin and the semiconductor chip and the adhesion between the thermosetting resin and the circuit board It has been conceived that it is possible to secure the reliability and to improve the reliability of the solder joint.

That is, the object of the present invention is a method of joining solder bumps for joining an electrode formed on a first substrate and a solder bump formed on a second substrate, the method including an alcohol or a carboxylic acid. Bonding the solder bumps to the electrodes using the bonding aid while melting the solder bumps, leaving the bonding aid. And a step of injecting a thermosetting resin between the first substrate and the second substrate, and heating the thermosetting resin so that the thermosetting resin is cured while dissolving the bonding aid in the thermosetting resin. And a step of joining solder bumps. This makes it possible to realize highly reliable flip chip bonding by dissolving the residue of the bonding aid in the thermosetting resin without removing the residue of the bonding aid.
Also, since it is not necessary to remove the residue of the joining aid,
The flip chip bonding technique can be applied to a fine semiconductor chip or the like. In addition, since it is not necessary to volatilize and remove the residue of the bonding assistant at a high temperature or perform bonding in a high-temperature hydrogen reducing atmosphere, flip-chip bonding can be performed even when a circuit board made of inexpensive resin is used. it can.

[0015] In the above-described method of joining solder bumps, it is preferable that the alcohol contains an aliphatic polyhydric alcohol or an ether thereof.

In the above method for bonding solder bumps, the carboxylic acid preferably contains abietic acid or a derivative thereof.

Further, the above object is to provide a solder bump joined body in which a first electrode formed on a first substrate and a second electrode formed on a second substrate are joined by solder bumps. It is preferable that a thermosetting resin is injected between the first substrate and the second substrate, and the thermosetting resin contains a bonding aid containing an alcohol or a carboxylic acid. . Thereby, the residue of the joining aid is dissolved in the thermosetting resin without removing the residue of the joining aid, so that a fine solder bump joined body can be provided. Also,
Since it is not necessary to heat at a high temperature in order to volatilize the residue of the bonding assistant, a solder bump bonded body using a circuit board made of an inexpensive resin can be provided.

In the above-mentioned solder bump joined body,
The alcohol preferably contains an aliphatic polyhydric alcohol or an ether thereof.

In the above-mentioned solder bump joined body,
The carboxylic acid preferably contains abietic acid or a derivative thereof.

[0020] The above object is also a method of joining solder bumps for joining an electrode formed on a first substrate and a solder bump formed on a second substrate, the method including an alcohol or a carboxylic acid, A step of applying a bonding aid having a boiling point higher than the melting point of the solder bump on the electrode, and heating at a temperature higher than the melting point of the solder bump and lower than the boiling point of the bonding aid, to the electrode. Bonding the solder bumps, injecting a thermosetting resin between the first substrate and the second substrate without removing the bonding aid, and heating the thermosetting resin. And dissolving the bonding aid in the thermosetting resin when the resin is cured.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for joining solder bumps according to one embodiment of the present invention will be described with reference to FIGS. FIG.
2A to 2C are sectional views showing the steps of the method for bonding solder bumps according to the present embodiment.

First, the circuit board 12 on which the electrodes 10 are formed
Is prepared (see FIG. 1A).

Next, the circuit board 1 is spin-coated.
2, a bonding aid 14 containing a carboxylic acid or alcohol
Is applied (see FIG. 1B).

Next, a semiconductor chip 20 having the solder bumps 18 formed on the electrodes 16 is prepared, and the solder bumps 18 of the semiconductor chip 20 are aligned with the electrodes 10 of the circuit board 12 (see FIG. 1C). ).

Next, flip chip bonding is performed by heating (see FIG. 2A). The heating temperature at the time of performing the flip chip bonding is higher than the melting point of the solder bump 18 and lower than the boiling point of the bonding aid 14.

In this embodiment, flip-chip bonding can be performed without using a reducing atmosphere.
This is particularly useful when flip-chip bonding is performed using a circuit board or the like that cannot withstand the above reducing atmosphere at high temperatures.

When performing flip chip bonding,
It is desirable to perform flip chip bonding in a nitrogen atmosphere to prevent oxidation of the bonding aid 14 and the like.
When the temperature is set to 50 ° C. or lower, the oxidation of the bonding assistant can be suppressed, so that the flip-chip bonding can be performed in the air.

Next, a thermosetting resin 22 made of a liquid epoxy resin is injected between the circuit board 10 and the semiconductor chip 20 without washing or volatilizing the residue of the bonding assistant 14. This thermosetting resin 22 functions as an underfill material.

Next, the thermosetting resin is heated at a temperature higher than the curing temperature of the thermosetting resin 22 to cure the thermosetting resin. At this time, the residue of the bonding assistant 14 dissolves in the thermosetting resin. The method of joining solder bumps according to the present embodiment is performed by dissolving the residue of the bonding aid 14 in the thermosetting resin 22 without washing or volatilizing the residue of the bonding aid 14. Between the thermosetting resin 2 and the circuit board 12
It is characterized in that the adhesion between the semiconductor chip 2 and the semiconductor chip 20 is ensured, and that a highly reliable solder joint is realized. Since it is not necessary to clean or volatilize the residue of the bonding assistant 14, the flip-chip bonding technology can be applied to a fine semiconductor chip. Further, since it is not necessary to heat at a high temperature to volatilize the bonding assistant 14, flip chip bonding can be performed even when a circuit board made of inexpensive resin is used.

(Joint Aid) In the present embodiment, the following carboxylic acids and alcohols are used as the join aid.

The carboxylic acid used as a bonding assistant may be any one that can cover the surface of the electrode 10 while the solder bump 18 is melted and wetted with the electrode 10.

For example, a carboxylic acid having a high boiling point, such as oleic acid or stearic acid, has a low activity and tends to leave a residue, which causes a decrease in the hardness of the thermosetting resin 22.

Therefore, as the carboxylic acid used as a bonding aid in the present embodiment, it is desirable to use a cyclic hydrocarbon carboxylic acid, particularly rosin acid (resin acid). As rosin acid, for example, abietic acid can be used. Further, not only abietic acid but also derivatives of abietic acid such as neoabietic acid can be used. Furthermore, high activity can be obtained by adding succinic anhydride or the like as an activator to rosin acid.

The alcohol used as a bonding assistant may be any alcohol that can cover the surface of the electrode 10 while the solder bump 18 is melted and the electrode 10 is kept wet.

For example, since a monohydric alcohol generally has a low boiling point, it can be applied only to a low melting point solder material such as Sn-In or Sn-Bi eutectic. Further, in this case, it is necessary to lower the bonding temperature, so that the oxide film may not be sufficiently removed.

Accordingly, the alcohol used as the bonding assistant 14 includes divalent aliphatic alcohols such as tetramethylene glycol and pentamethylene glycol, trivalent alcohols such as glycerin and hexaglycerol, diethylene glycol, triethylene glycol, tetraethylene glycol, and the like. Polyglycols such as glycol, polyethylene glycol, dipropylene glycol, and polypropylene glycol, and ethers of glycol oligomers such as diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, and tripropylene glycol monomethyl ether can be used.

(Solder Material) As a solder material used for the solder bump, for example, Pb-Sn, Sn-Sb, Sn-I
n, Sn-Bi, Sn-Ag, or the like can be used.
The solder material is not limited to these,
It can be applied to any solder materials.

(Electrode Material) Conventionally, the electrode material on the counter substrate side to be joined to the solder bumps has an A surface on the surface to prevent oxidation.
In many cases, a u film or the like was formed.

However, according to the present invention, the metal oxide film on the electrode surface is removed by the activity of the alcohol or carboxylic acid during heating in the soldering step, and the alcohol or carboxylic acid covering the electrode surface is removed from the electrode surface. The Au film is not necessarily formed on the electrode surface because reoxidation of the electrode is prevented.

For example, even when an inexpensive Pd film is formed on the surface of the electrode, the flip chip bonding can be performed without causing any particular problem.

The solder bumps can be directly bonded to a Cu film widely used as a wiring material, a Ni film used as a barrier metal, and the like.

(Thermosetting resin) The thermosetting resin used as the underfill material is not particularly limited. For example, an epoxy resin in which a powder such as silica or alumina is mixed as a filler can be used. Further, a mixture of an epoxy resin and a polyfunctional acrylate may be used.

As described above, according to the present embodiment, the residue of the bonding aid is dissolved in the thermosetting resin without washing or volatilizing the residue of the bonding aid, thereby providing high reliability. Flip chip bonding can be realized.

Further, according to the present embodiment, since it is not necessary to clean or volatilize the residue of the bonding assistant, the flip chip bonding technique can be applied to fine semiconductor chips.

Further, according to the present embodiment, since it is not necessary to heat at a high temperature to volatilize the bonding assistant, flip-chip bonding can be performed even when a circuit board made of an inexpensive resin is used. .

[Modified Embodiment] The present invention is not limited to the above-described embodiment, and various modifications are possible.

For example, in the above embodiment, the solder bumps are formed on the semiconductor chip side, but may be formed on the circuit board side. Further, solder bumps may be formed on both the semiconductor chip side and the circuit board side.

In the above embodiment, the case where the solder bump joint is formed using the circuit board and the semiconductor chip has been described as an example. However, the present invention is applied to the case where the solder bump joint is formed using any substrate. be able to.

[0049]

EXAMPLES Examples 1 to 3 1 g of solder powder was put into 5 g of a bonding aid as shown in Table 1, heated at 280 ° C., and the concentration of metal ions contained in the solution was measured. Specifically, the concentrations of Sn ions and Pb ions were measured. Table 1
Shows the measurement results.

[0050]

[Table 1]

In Table 1, the oxidation amount indicates the ratio of oxygen to the entire solder powder taken in the form of a metal oxide or the like, and the metal ion concentration indicates the metal content determined by emission spectroscopy. The values of the ion concentration are shown. Succinic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) was used as the activator of Comparative Example 2.

As can be seen from Table 1, a large amount of Sn ions was contained in the residue of the bonding aid, and the more the oxidation proceeded, the larger the amount of Sn ion eluted into the residue of the bonding aid. .

Example 4 When the components were analyzed by heating tetraethylene glycol, carboxylic acids as shown in the broken lines in FIG. 3 were detected. FIG. 3 is a diagram showing carboxylic acids and the like generated when tetraethylene glycol is heated. For the analysis, component identification by GC-Mas was used.

According to the analysis result, when tetraethylene glycol is heated, carboxylic acid is generated by oxidation of alcohol at both ends or by oxidation of alcohol generated by hydrolysis of ether bond. Conceivable. And it is thought that this carboxylic acid exerts flux activity.

[Examples 5 to 12] A bonding aid as shown in Table 2 was dropped on a metal plate, and a diameter of 0.8 was applied onto the metal plate.
mm solder balls were placed. As a metal plate, a Cu plate or a Ni plate was used. As the bonding aid, a polyhydric alcohol as shown in Examples 5 to 11, or a carboxylic acid as shown in Example 12 was used. As solder balls, S
n-3.5Ag or Sn-37Pb was used.

Next, the metal plate was heated using a hot plate in a nitrogen atmosphere, and the wet state between the solder balls and the metal plate was observed. The heating temperature of the solder ball made of Sn-3.5Ag was set to 260C, and the heating temperature of the solder ball made of Sn-37Pb was set to 220C.

[0057]

[Table 2]

In Table 2, ◎, △, Δ, and × indicate the wet state of the metal plate 26 and the solder ball 24, respectively, as shown in FIGS. 4 (a), 4 (b), 4 (c), and 4 ( d). FIG. 4 is a diagram showing a wet state of the metal plate and the solder balls.

When the polyhydric alcohols shown in Examples 5 to 11 were used as the bonding aid, the wet state was ◎, ○, or Δ. When a carboxylic acid as shown in Example 14 was used as a bonding aid, the wet state was ◎ or ○. Therefore, if such a bonding aid is used, a good wet state can be realized.

On the other hand, when the bonding aid was not applied as shown in Comparative Example 3, the wet state was x, and a good wet state could not be realized.

[Examples 13 to 16] First, the glass epoxy substrate was washed with water, and then the glass epoxy was washed with isopropyl alcohol.

Next, a bonding aid as shown in Table 3 was applied to the glass epoxy substrate and heated in an IR reflow furnace at a maximum temperature of 260 ° C.

[0063]

[Table 3]

Next, in Examples 13 to 16, a thermosetting resin 30 was applied without washing the residue of the bonding assistant, and a glass epoxy substrate 28 was attached as shown in FIG. FIG. 5 is a diagram in which a glass epoxy substrate is bonded using a thermosetting resin.

On the other hand, in Comparative Examples 4 to 7, after cleaning the residue of the bonding assistant, a thermosetting resin 30 was applied to the substrate.
Similarly, a glass epoxy substrate 28 was bonded. When cleaning the residue of the bonding assistant in Comparative Examples 4 to 7, a cleaning liquid in which xylene and isopropyl alcohol (IPA) were mixed at a ratio of 9: 1 was used. In the specification of the present application, the thermosetting resin A is bisphenol A
Epoxy resin and a mixture of trifunctional acrylates as a main component, a tertiary amine as a curing agent, and an alumina powder of 40%.
It is a thermosetting resin produced by mixing at a ratio of wt%.
The thermosetting resin B is an epoxy-based underfill material (EH0545, manufactured by Hysole Co., Ltd.).

Next, the glass epoxy substrates 28 were pulled toward each other in the direction shown by the arrow in FIG. 5, and the adhesive strength was measured.

As can be seen from Table 3, the difference in adhesive strength between the presence and absence of washing of the bonding aid was small. Rather, the adhesive strength greatly depends on the type of thermosetting resin.

[Examples 17 and 18] A mixture obtained by adding tetraethylene glycol to a thermosetting resin composed of thermosetting resin A was heated and cured, thereby producing a test piece. In Example 17, tetraethylene glycol was added to 1
A test piece prepared by adding wt%, Example 18 is a test piece prepared without adding tetraethylene glycol, and Comparative Example 8 is a test piece prepared by adding 0.5 wt% of tetraethylene glycol.

Next, the relationship between the ambient temperature and the elastic modulus of each test piece was measured. FIG. 6 is a graph showing the relationship between the ambient temperature and the elastic modulus of the thermosetting resin. The horizontal axis in FIG. 6 indicates the ambient temperature, and the vertical axis indicates the elastic modulus.

As shown in FIG. 6, at around room temperature, the elastic modulus of the thermosetting resin was almost the same in all of Examples 17 and 18 and Comparative Example 8.

On the other hand, when the ambient temperature was increased, the elastic modulus of Example 18 was lower than that of Comparative Example 8;
The elastic modulus of Example 17 was lower than that of Example 17. This is presumably because, when the amount of tetraethylene glycol added to the thermosetting resin increases, the glass transition temperature decreases, and the resin easily softens even at a low temperature.

Generally, the operation guarantee temperature of a semiconductor chip is 12
0 ° C. and the ambient temperature of a normal semiconductor chip is 80
About 100C to about 100C. Therefore, in order to extend the life of the element of the semiconductor chip, it is desirable to reduce the change in the elastic modulus with respect to the temperature change in order to reduce the thermal expansion distortion.

Therefore, when tetraethylene glycol is used as a bonding aid, the concentration of tetraethylene glycol dissolved in the thermosetting resin should be 1 wt% or less, preferably 0.5 wt% or less. desirable.

Example 19 Tetraethylene glycol was applied on a 15 mm square resin built-up substrate by spin coating. The amount of tetraethylene glycol applied was 2.3 mg.

Next, this built-up substrate was heated on a hot plate at 230 ° C. for 1 minute, and then the residual amount of tetraethylene glycol was measured. As a result, the residual amount of tetraethylene glycol was 0.9 mg.

Example 20 First, a semiconductor chip on which solder bumps were formed was prepared. Silicon was used as the material of the semiconductor chip, and the substrate size was 13 mm square.
Solder bumps were arranged in 45 × 45 pieces to form 2025 solder bumps. The pitch at which the solder bumps were formed was 210 μm. The material of the solder bump is Sn-37Pb, the size of the solder bump is φ120 μm, and the height of the solder bump is 10
It was set to 0 μm.

Further, a built-up substrate on which electrodes facing the solder bumps were formed was prepared. Bismaleimide-triazine resin (BT resin) was used as the material of the built-up substrate, and the size of the built-up substrate was 15 mm square. Ni / Cu was used as the electrode material.

Next, a bonding aid was applied to the built-up substrate by spin coating. Tetraethylene glycol was used as a joining aid. The application conditions of the joining aid were 3500 rpm and 60 seconds.

Next, the built-up substrate and the semiconductor chip were aligned, and flip chip bonding was performed using a flip chip bonder. The peak temperature at the time of performing flip chip bonding was 230 ° C.

Next, a thermosetting resin A was applied to each of the sample in which the residue of the bonding aid was not washed and the sample in which the residue of the bonding aid was washed, and underfilling was performed. A sample in which the residue of the joining aid was not washed was Example 20, and a sample in which the residue of the joining aid was washed was Comparative Example 4.

Next, a heat cycle test at -55 ° C. to 125 ° C. was performed to determine whether there was a disconnection. FIG. 7 is a graph showing the results of the heat cycle test. The horizontal axis in FIG. 7 indicates the number of cycles, and the vertical axis indicates the defect rate.

As a result, the defective rates of Example 20 and Comparative Example 9 were almost the same, and it was found that the defective rate was not particularly high depending on whether or not the residue of the bonding aid was washed.

[Examples 21 and 22] Samples for an ion migration test as shown in FIG. 8 were prepared. FIG.
It is sectional drawing which shows the sample of an ion migration test.

The sample shown in FIG. 8 was prepared as follows. That is, first, the comb electrodes 34 were formed on the resin substrate 32 at a pitch of 150 μm, and thereafter, the insulating film 38 was formed on the entire surface. Next, the insulating film 38 was patterned by using the photolithography technique to form openings reaching the grid electrodes 34 at a pitch of 150 μm.

Next, the grid electrode 34 having the opening formed therein is formed.
A Sn-35Ag solder bump 36 was formed thereon.

Next, a bonding aid was applied onto the solder bumps 36, and reflow was performed at a peak temperature of 260 ° C.
In Example 21, rosin was applied as a bonding aid, and in Example 22, tetraethylene glycol was applied as a bonding aid. Comparative Example 10 was obtained by applying a rosin as a joining aid and then washing the residue of the joining aid, and Comparative Example 11 was applying tetraethylene glycol as a joining aid and washing the residue of the joining aid. is there.

Next, Examples 21 and 22, Comparative Examples 10 and 1
With respect to No. 1, a thermosetting resin 40 was applied to the entire surface. The thermosetting resin A described above was used as the thermosetting resin.

Next, an ambient temperature of 121.degree.
H. When an ion migration test was performed for 504 hours at an applied voltage of 5 V to measure the presence or absence of a short circuit,
No short circuit occurred in any of Examples 21 and 22, and Comparative Examples 10 and 11.

[0089]

As described above, according to the present invention, high reliability can be obtained by dissolving the residue of the bonding aid in the thermosetting resin without washing or volatilizing the residue of the bonding aid. Can be realized.

Further, according to the present invention, since it is not necessary to clean or volatilize the residue of the bonding assistant, the flip chip bonding technique can be applied to fine semiconductor chips.

Further, according to the present invention, since it is not necessary to heat at a high temperature to volatilize the bonding assistant, flip chip bonding can be performed even when a circuit board made of inexpensive resin is used.

[Brief description of the drawings]

FIG. 1 is a process cross-sectional view (part 1) illustrating a method for bonding solder bumps according to an embodiment of the present invention.

FIG. 2 is a process cross-sectional view (part 2) illustrating the method of joining solder bumps according to one embodiment of the present invention.

FIG. 3 is a view showing a carboxylic acid and the like generated when tetraethylene glycol is heated.

FIG. 4 is a diagram showing a wet state of a metal plate and a solder ball.

FIG. 5 is a diagram in which a glass epoxy substrate is bonded using a thermosetting resin.

FIG. 6 is a graph showing a relationship between an ambient temperature and an elastic modulus of a thermosetting resin.

FIG. 7 is a graph showing the results of a heat cycle test.

FIG. 8 is a cross-sectional view showing a sample for an ion migration test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Electrode 12 ... Circuit board 14 ... Joining agent 16 ... Electrode 18 ... Solder bump 20 ... Semiconductor chip 22 ... Thermosetting resin 24 ... Solder ball 26 ... Metal plate 28 ... Glass epoxy board 30 ... Thermosetting resin 32 ... Resin board 34 grid electrode 36 solder bump 38 insulating film 40 thermosetting resin

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E319 AA03 AB05 BB04 CC33 CD21 GG03 5F044 KK02 LL05 LL11 RR17 RR19

Claims (6)

[Claims] 1. A method of joining solder bumps for joining an electrode formed on a first substrate and a solder bump formed on a second substrate, the method comprising a bonding aid comprising an alcohol or a carboxylic acid. Bonding the solder bumps to the electrodes using the bonding aid while melting the solder bumps; and A step of injecting a thermosetting resin between the first substrate and the second substrate; and a step of heating the thermosetting resin so as to be cured while dissolving the bonding aid in the thermosetting resin. A method for bonding solder bumps, comprising: 2. The solder bump joining method according to claim 1, wherein the alcohol includes an aliphatic polyhydric alcohol or an ether thereof. 3. The method for bonding solder bumps according to claim 1, wherein said carboxylic acid includes abietic acid or a derivative thereof. 4. A first electrode formed on a first substrate,
A solder bump joined body in which a second electrode formed on a second substrate is joined by a solder bump, wherein a thermosetting resin injected between the first substrate and the second substrate is used. A solder bump joined body, wherein the thermosetting resin contains a joining aid containing alcohol or carboxylic acid. 5. The solder bump assembly according to claim 4, wherein the alcohol includes an aliphatic polyhydric alcohol or an ether thereof. 6. The solder bump assembly according to claim 4, wherein the carboxylic acid includes abietic acid or a derivative thereof.