JP3397955B2 - Solder bump formation method, substrate connection method using solder bump, and removal method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder bump forming method in face-down mounting using solder bumps, a board connecting method using solder bumps, and a detaching method thereof.

[0002]

2. Description of the Related Art In a method of mounting an electronic component such as a semiconductor element or a circuit board face down on a circuit board such as a printed circuit board, there is a method of using a solder member as a connecting member. This method forms solder bumps on electrodes on a circuit board such as a printed circuit board, and heats and melts the solder bumps to mount an electronic component such as a semiconductor element or a circuit board face down on the circuit board such as a printed circuit board. .

Conventionally, solder bumps on electrodes have been formed by a plating method or a vapor deposition method. The plating method is a method of forming solder bumps by electroplating. The vapor deposition method is a method in which a metal mask having perforations is placed on a circuit board and solder bumps are formed in the perforations of the metal mask by sputtering or electron beam vapor deposition. However, if solder bumps are formed on the electrodes by a plating method or a vapor deposition method, the working process becomes complicated.

On the other hand, a solder bump forming method which can simplify the working process and reduce the equipment cost has been considered. This solder bump forming method is shown in FIG. In this solder bump forming method, solder particles 3 are arranged on a transfer plate 2 using a mask 1, and the transfer plate 2 is arranged so that the solder particles 3 are arranged on an electrode 5 of a circuit board 4.
Is pressed against the circuit board 4, the solder particles 3 are arranged on the circuit board 4, and then the solder particles 3 are heated and melted to form the solder bumps 6. Perforations corresponding to the electrodes 5 are formed in the mask 1.
A passivation layer 7 for protecting the surface of the circuit board 4 is formed on the circuit board 4 so as not to cover the electrodes 5. A flux 8 is applied on the electrodes 5 and the passivation layer 7.

Next, a method of forming the solder bumps 6 will be described with reference to FIGS. As shown in FIG. 7A, the mask 1 is placed on the transfer plate 2. The solder particles 3 are placed on the mask 1, the solder particles 3 are inserted into the holes of the mask 1, and unnecessary solder particles 3 on the mask 1 are removed by a squeegee 9. After that, the mask 1 is removed to place only the solder particles 3 on the transfer plate 2. The solder particles 3
Adhere to the transfer plate 2 with a weak bonding force.

As shown in FIG. 7B, the solder particles 3 arranged on the transfer plate 2 are aligned with the electrodes 5 and the transfer plate 2 is pressed against the circuit board 4. afterwards,
As shown in FIG. 7C, the transfer plate 2 is separated from the circuit board 4. At this time, due to the viscosity of the flux 8, the solder particles 3 are held on the circuit board 4, the solder particles 3 are separated from the transfer plate 2, and the solder particles 3 are collectively placed on the circuit board 4. Will be placed.

As shown in FIG. 7D, the circuit board 4
The solder bumps 6 are formed on the electrodes 5 by heating and melting the solder particles 3 arranged above.

By such a method, the solder bumps 6 can be collectively formed on the electrodes 5 on the circuit board 4,
The work process can be simplified and the equipment cost can be reduced.

Further, as shown in FIG. 8A, when the circuit board 10 is mounted face down on the circuit board 4 on which the solder bumps 6 are formed on the electrodes 5, the heater 11 is placed from below the circuit board 4. The circuit board 4 and the circuit board 10 are connected by heating and melting the solder bumps 6.

[0010]

However, in the solder bump forming method shown in FIG. 7, when the circuit board 4 is miniaturized or miniaturized, the solder particles 3 are transferred to the transfer plate 2 so as to correspond to the electrodes 5 of the circuit board 4. It becomes difficult to dispose the solder particles 3 on the transfer plate 2 and the solder particles 3 arranged on the transfer plate 2 on the electrodes 5 of the circuit board 4. Therefore, as shown in FIG. 7C, the solder particles 3 are separated from the electrodes 5 of the circuit board 4 and are disposed on the edges of the passivation film 7.
The solder particles 3 which are separated from the electrodes 5 and arranged on the edges of the passivation film 7 do not flow out onto the electrodes 5 due to surface tension even if they are heated and melted. Therefore, FIG.
As shown in (d), there arises a problem that the solder bump 6 is not formed on the electrode 5.

Further, in the conventional solder bump shape, the circuit board 4 and this circuit board 4 are used for face-down mounting.
In addition, there is a problem that poor connection accuracy occurs when the alignment accuracy with the electronic component or the circuit board to be mounted face down is poor.

Furthermore, when face down mounting is performed using the solder bumps 6, the circuit board 4 is heated by the heater 11.
Also, since the circuit board 10 is heated, if the coefficient of thermal expansion of the circuit board 4 is larger than that of the circuit board 10, as shown in FIG. The board 4 expands more than the circuit board 10. Therefore, when the heating by the heater 11 is stopped and the solder bumps 6 are solidified, the circuit board 4 becomes
The circuit board 4 and the circuit board 10 are contracted to a greater extent.
A thermal strain occurs between and. Therefore, a stress is applied to the connection member formed by the solder bumps 6 between the circuit board 4 and the circuit board 10, the connection member is broken, and a connection failure occurs. The same problem occurs when the coefficient of thermal expansion of the circuit board 4 is smaller than that of the circuit board 10.

[0013]

[0014]

Means for Solving the Problems The invention according to claim 1,
Place solder particles on the electrodes formed on the substrate and
Crush the solder particles and add the crushed solder particles.
A solder bump is formed on the electrode of the substrate by heating and melting , and the solder bump formed on the substrate is crushed to flatten the solder bump to increase the diameter of the solder bump. Therefore, by flattening the solder bumps and increasing the diameter of the solder bumps, when the other substrate is connected to the substrate on which the solder bump is formed, even if the other substrate to be connected is slightly misaligned, it is formed on those substrates. The corresponding electrodes are connected. Therefore, the substrates are connected to each other even if the alignment accuracy is poor.

According to a second aspect of the present invention, two substrates are prepared, and solder particles are arranged on the electrodes formed on the substrates.
The crushed solder particles, the crushed solder particles
Is heated and melted to form solder bumps on the electrodes of the substrate, and the solder bumps formed on the substrate are formed.
Flatten the solder bumps by crushing the solder bumps
Increasing the diameter of the solder bump by, brought into contact with the solder bumps on the solder bumps and the other of said substrate of one of the substrates, connecting the two substrates by heating and melting at least one of the solder bumps . Therefore, by increasing the diameter of the solder bumps formed on the substrates, the allowable range of alignment accuracy between the two substrates is expanded, so that even if the two substrates are misaligned, the corresponding electrodes formed on the two substrates will be connected. It

According to a third aspect of the present invention, a first substrate and a second substrate are prepared, and solder particles are formed on the electrodes formed on the substrate.
Place the child, crush the solder particles, crushed
The base is prepared by heating and melting the solder particles.
And forming a first solder bump on the electrode plate, the first and second solder bumps formed before Symbol second substrate by using a high solder particles melting point than solder bumps, the first The first substrate by bringing the solder bump and the second solder bump into contact with each other, and heating the first solder bump at a temperature lower than the melting point of the second solder bump to melt only the first solder bump. And the second substrate. Therefore, by melting only the first solder bump and fixing it around the second solder bump to connect the first substrate and the second substrate, after connecting the first substrate and the second substrate, also the second solder bumps is maintained without deformation in a state in which the first bumps and the second bumps are separated.

According to a fourth aspect of the invention, the first substrate and the second substrate
Prepare a substrate and solder particles on the electrodes formed on the substrate.
Place the child, crush the solder particles, crushed
The base is prepared by heating and melting the solder particles.
Forming the first solder bump on the electrode of the plate together
Solder particles having a higher melting point than the first solder bump
A second solder bump on the second substrate using a solder.
The first solder bump and the second solder bump.
The first solder bump and the second solder bump.
First, heat at a temperature lower than the melting point of the solder bump.
By melting only the solder bumps of
Connecting the substrate and the second substrate, said heating said first solder bumps and the second bumps at the first temperature lower than the higher the second solder bumps melting point than the melting point of the solder bumps and to release the said second substrate and the first substrate by melting only the second of said first solder bump which is fixed around the solder bumps. Therefore, even when the first substrate and the second substrate are separated from each other, the second solder bump is maintained without being deformed.

According to a fifth aspect of the present invention, a first substrate and a second substrate are prepared, first solder particles are arranged on a first electrode formed on the first substrate, and Second solder particles having a higher melting point and a larger volume than the first solder particles are arranged in parallel with the first solder particles on the first substrate, and the first solder is applied by the second substrate. Crushing the particles and the second solder particles, the first solder particles by heating at a temperature lower than the melting point of the second solder particles to melt only the first solder particles the first One electrode is connected to the second electrode formed on the second substrate, and the first solder particles and the second solder particles are heated at a temperature higher than the melting point of the second solder particles. Of the second solder particles by heating and melting the second solder particles It was to widen the distance between the second substrate and the first substrate in terms tension. Therefore, the length of the connecting portion formed by the first solder particles and connecting the first electrode and the second electrode becomes long, and a structure resistant to thermal strain can be easily obtained. Further, by crushing the first solder particles, a part of the first solder particles that are arranged apart from the electrode spreads on the electrode. Thus, solder bumps are formed on the electrodes.

According to a sixth aspect of the present invention, a first substrate and a second substrate are prepared, the first solder particles are arranged on the first electrode formed on the first substrate, and Second solder particles having a higher melting point and a larger volume than the first solder particles are arranged in parallel with the first solder particles on the first substrate, and the first solder is applied by the second substrate. Crushing particles and the second solder particles, the solder bumps by melting only the first solder particles by heating the first solder particles at a temperature lower than the melting point of the second solder particles. Formed, the second electrode formed on the second substrate is brought into contact with the solder bumps to connect the first electrode and the second electrode, and the melting point of the second solder particles is higher than the melting point of the second solder particles. The solder bumps and the second solder particles at high temperature The increase the distance of the first substrate by the surface tension of the By heating to melt the second solder particles and the second substrate. Therefore, the length of the connection portion formed by the solder bump and connecting the first electrode and the second electrode becomes long, and a structure resistant to thermal strain can be easily obtained. Further, by crushing the first solder particles, a part of the first solder particles that are arranged apart from the electrode spreads on the electrode. Thus, solder bumps are formed on the electrodes.

[0020] According to a seventh aspect, claim 5 or 6 Symbol
In a substrate connecting method using a mounted solder bump, a plurality of types of second solder particles having a higher melting point as the volume increases are provided, and the second solder particles are selectively melted by heating and melting. The surface tension of the second solder particles widens the gap between the first substrate and the second substrate. Therefore, the temperature for heating the plurality of second solder particles arranged between the first substrate and the second substrate is adjusted, and the second solder particles melted by selectively melting the second solder particles. The surface tension of the solder particles can increase the distance between the first substrate and the second substrate. Therefore, the distance between the first substrate and the second substrate is adjusted.

According to an eighth aspect of the present invention, the first electrode having the first electrode formed thereon and the second electrode having the second electrode formed on the center side of the first electrode are displaced from each other. Prepare a second substrate, which has a lower coefficient of thermal expansion than the substrate, and form it on the substrate.
Place the solder particles on the electrode and press the solder particles.
Crush and heat the crushed solder particles to melt
A second solder bump on said first said and first solder bumps on a substrate of the second substrate is formed by Rukoto, it is brought into contact with said second solder bump and said first solder bump, the second The one solder bump and the second solder bump are heated and melted to be connected. Therefore, when the solder bumps are heated and melted, the molten solder bumps generate a force to eliminate the inclination toward the center side due to the surface tension, so that the first substrate and the second substrate are separated from each other. When connecting, the expansion of the first substrate is suppressed by the molten solder bumps, and the second substrate is expanded. Therefore, when the heating of the solder bumps is stopped and the solder bumps are solidified, the difference in shrinkage between the first substrate and the second substrate becomes small.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A solder bump forming method according to an embodiment which is the basis of the present invention will be described with reference to FIG. The same parts as those described with reference to FIGS. 7 and 8 are represented by the same reference numerals, and the description thereof will be omitted. In the solder bump forming method according to the present embodiment, the solder particles 3 are arranged on a circuit board 4 which is a substrate, the solder particles 3 are crushed, and then the solder particles 3 are heated and melted to melt the circuit board. The solder bump 6 is formed on the electrode 5 of No. 4.

The details will be described below in order along with FIGS. 1 (a) to 1 (c). In the method of forming the solder bumps 6, first, as shown in FIG. 1A, the solder particles 3 are arranged on the circuit board 4. The method of arranging the solder particles 3 on the circuit board 4 is the same as described in the above-mentioned conventional example, after arranging the solder particles 3 on the transfer plate by using a mask and then the solder on the transfer plate. By aligning the particles 3 with the electrodes 5 and pressing the transfer plate against the circuit board 4, the particles 3 are collectively arranged on the circuit board 4.

Next, as shown in FIG. 1 (b), the solder particles 3 arranged on the circuit board 4 are pressed by the pressing device 2
Crush with 1. Since the pressing device 21 is an existing pressing device, its description is omitted. The press device 21
By crushing the solder particles 3 by means of the above, the solder particles 3 separated from the electrodes 5 and arranged on the edge of the passivation film 7 are crushed by the pressing device 21, and a part of the solder particles 3 is laid on the electrodes 5. Spread to the electrode 5
To contact.

As shown in FIG. 1 (c), the circuit board 4
The solder bumps 6 are formed by heating and melting the upper solder particles 3. At this time, the electrode 5
Since the solder particles 5 arranged apart from the top are in contact with the electrodes 5, when they are heated and melted, they are positioned on the electrodes 5 by wet back. Then, the solder bumps 6 are formed on the electrodes 5.

As described above, after the solder particles 3 arranged on the circuit board 4 are crushed, the solder particles 3 are heated and melted to form the solder bumps 6, so that the solder particles 3 are removed from the electrodes 5. The solder bumps 6 can be collectively formed on the electrode 5 even if the solder bumps 6 are separated and arranged on the edge of the passivation film 7. As a result, defective bump formation is prevented and the yield is improved.

[0027] be described with reference to board connection method in FIG. 2 with solder bumps forming method and solder bumps of an embodiment of the invention of claim 1 and 2 wherein. The same parts as those described in the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted (the same applies to other embodiments hereinafter). The solder bump forming method and the substrate connecting method using the solder bump in the present embodiment are the same as those described above on the first electrode 5 on the circuit board 4 which is the substrate and on the second electrode 23 on the LSI chip 22 which is the substrate. A substantially hemispherical solder bump is formed by the solder bump forming method according to the embodiment. Then, the substantially hemispherical solder bumps formed on the first electrode 5 and the second electrode 23 are crushed and flattened, so that the first solder bumps flattened on the first electrode 5 are formed. Then, the second solder bump 25 is formed on the second electrode 23. Then, the LSI chip 22 is mounted face down on the circuit board 4.

The method for forming the first solder bumps 24 and the second solder bumps 25 is the same as in the above-described embodiment, in which solder particles are arranged on the circuit board 4 and the LSI chip 22, respectively. After the solder particles are crushed, the solder particles are heated and melted to form substantially hemispherical solder bumps on the first electrode 5 and the second electrode 23. After that, the substantially hemispherical solder bumps formed on the first electrodes 5 are crushed and flattened to increase the diameter of the solder bumps and form the first solder bumps 24. Also, the substantially hemispherical solder bump formed on the second electrode 23 is crushed and flattened to increase the diameter of the solder bump and form the second solder bump 25.

The circuit board 4 and the LS are formed by using the first solder bumps 24 and the second solder bumps 25.
2A and 2B, the circuit board 4 and the LSI chip 22 are opposed to each other, and the first solder bump 24 and the second solder bump 24 are connected to each other. 25 is brought into contact. Then, the first solder bump 24 and the second solder bump 2
By heating and melting the first electrode 5
And the second electrode 23 are connected to each other, and the LSI chip 22 is mounted face down on the circuit board 4.

As described above, the first solder bump 24 and the second solder bump 25 are flattened to increase the diameters of the first solder bump 24 and the second solder bump 25, so that the circuit board 4 and the LSI chip 22 are connected to each other. Since it is possible to widen the allowable range of the positioning accuracy in the first electrode 5 even if the circuit board 4 and the LSI chip 22 are misaligned.
Can be connected to the second electrode 23. Therefore, the yield is improved.

[0031] be described with reference to board connection method and a substrate removal method using the solder bumps of one embodiment of the invention of claim 3 and 4 according to FIG. The board connecting method and the board removing method using the solder bumps according to the present embodiment are the same as the first electrode 5 on the circuit board 4 which is the first board.
A first solder bump 24 is formed on the second substrate, and a second solder bump 26 having a melting point higher than that of the first solder bump 24 is formed on the second electrode 23 of the LSI chip 22 which is the second substrate. By heating the first solder bump 24 at a temperature higher than the melting point of the first solder bump 24 and lower than the melting point of the second solder bump 26, and melting only the first solder bump 24, Connection with the LSI chip 22, and
Remove it.

The details will be described below. In the method of connecting the LSI chip 22 to the circuit board 4, the solder particles having a melting point higher than that of the first solder bump 24 are used for the LS.
The solder particles placed on the I-chip 22 are crushed, and the crushed solder particles are heated and melted to have a melting point higher than that of the first solder bumps 24. The high second solder bumps 26 are formed.

Then, as shown in FIG. 3A, the LSI chip 22 is opposed to the circuit board 4, and the second solder bump 26 is brought into contact with the first solder bump 24. Then, the first solder bump 24 is heated at a temperature higher than the melting point of the first solder bump 24 and lower than the melting point of the second solder bump 26 to melt only the first solder bump 24. As shown in FIG. 3B, a connection member for connecting the first electrode 5 and the second electrode 23 by fixing the molten first solder bump 24 around the second solder bump 24. 27
Is formed, and the LSI chip 22 is mounted face down on the circuit board 4.

The method of removing the LSI chip 22 from the circuit board 4 is to heat the connecting member 27 at a temperature higher than the melting point of the first solder bump 24 and lower than the melting point of the second solder bump 26. , The first solder bumps 24 fixed around the second solder bumps 26 are melted. Then, the LSI chip 22 is removed from the circuit board 4.

In this way, the second solder bump 26 having a melting point higher than that of the first solder bump 24 is formed. Then, the first solder bump 24 is heated at a temperature higher than the melting point of the first solder bump 24 and lower than the melting point of the second solder bump 26 to melt only the first solder bump 24, and the circuit board 4 and the LSI chip 22. And connect. Accordingly, even after the LSI chip 22 is mounted face down on the circuit board 4, the connection member 27 can be formed in a state where the first solder bump 24 and the second solder bump 26 are separated. Also, when the LSI chip 22 is removed from the circuit board 4, by heating the connection member 27 at a temperature higher than the melting point of the first solder bump 24 and lower than the melting point of the second solder bump 26, the first solder bump 24 Only the second solder bump 26 can be melted and separated from the second solder bump 26. Therefore, the second solder bump 26
Is not deformed, the LSI chip 22 is mounted face down on the circuit board 4 and then L
Even when the SI chip 22 is removed, there is no need to re-form solder bumps on the LSI chip 22 removed from the circuit board 4. Therefore, it becomes easy to redo the face-down mounting.

[0036] be described with reference to board connection method in FIG. 4 with solder bumps of an embodiment of the invention of claim 5 and 6 wherein. As shown in FIG. 4D, the substrate connecting structure obtained by the substrate connecting method using the solder bumps according to the present embodiment has the first electrode 5 and the second substrate 5 in the circuit board 4 which is the first substrate. The second electrode 23 of the LSI chip 22 is connected by the connecting member 28, and the second solder particles 29 are arranged between the circuit board 4 and the LSI chip 22. The connection member 28 is formed of a solder bump 30 [see FIG. 4 (c)]. The second solder particles 29 are the solder bumps 3
The volume is larger than 0 and the melting point is higher than that of the solder bump 30.

In the substrate connecting method using the solder bumps of the present embodiment, as shown in FIG. 4A, the first solder particles 3 forming the solder bumps 30 are arranged on the first electrodes 5. , The second solder particles 29 are arranged on the passivation film 7 on the circuit board 4.

As shown in FIG. 4B, the second electrode 23
The LSI chip 22 is opposed to the circuit board 4 so that the first solder particles 3 are located substantially vertically below
The first solder particles 3 and the second solder particles 29 are crushed by the LSI chip 22.

As shown in FIG. 4C, the first solder particles 3 are heated at a temperature lower than the melting point of the second solder particles 29 to heat the first solder particles 3. Only the solder particles 3 are melted to form the solder bumps 30, and the first electrodes 5 and the second electrodes 23 are connected.

Thereafter, the solder bumps 30 and the second solder particles 29 are heated and melted at a temperature higher than the melting point of the second solder particles 29. At this time, due to the surface tension of the melted second solder particles 29, the L
The SI chip 22 is lifted upward, and the melted solder bump 30 is stretched while being connected to the first electrode 5 and the second electrode 23. Then, the LSI chip 22 is lifted to a height where the surface tension of the melted solder bumps 30 and the weight of the LSI chip 22 and the surface tension of the melted second solder particles 29 are balanced.

As shown in FIG. 4 (d), the heating of the second solder particles 29 and the solder bumps 30 is stopped and the solder bumps 30 are solidified to form the connection member 28, and the circuit is formed. The LSI chip 22 is mounted face down on the circuit board 4 with the second solder particles 29 arranged between the substrate 4 and the LSI chip 22.

According to the board connecting method using the solder bumps, since the volume of the second solder particles 29 is larger than the volume of the solder bumps 30, the circuit board 4 and the LSI.
The distance from the chip 22 is separated by the second solder particles 29, and the length of the connecting member 28 is increased. As a result, the allowable range for thermal strain in the connecting member 28 can be expanded. Therefore, it is possible to prevent the connection member 28 from being broken by the thermal strain generated when the LSI chip 22 is mounted face down on the circuit board 4. Also, the circuit board 4
The second solder particles 29 can be easily arranged between the circuit board 4 and the LSI chip 22.
It is possible to increase the length of the connecting member 28 by separating it from the two. Therefore, a substrate connection structure that is resistant to thermal strain can be easily obtained. Further, by crushing the first solder particles 3, even if the first solder particles 3 are separated from the electrodes 5 and arranged on the edge of the passivation film 7, the solder bumps 6 are collectively formed on the electrodes 5. be able to. As a result, defective bump formation is prevented and the yield is improved.

[0043] be described with reference to board connection method in FIG. 5 using solder bumps one embodiment of the invention of claim 7, wherein. The board connection structure obtained by the board connection method using the solder bumps of the present embodiment is shown in FIGS.
As shown in FIG. 3, solder particles 31, 32, 3 which are three kinds of second solder particles having different sizes are provided between the circuit board 4 which is the first substrate and the LSI chip 22 which is the second substrate.
3 are arranged. The solder particles 31 have a smaller volume than the other two solder particles 32 and 33, and have a lower melting point than the other two solder particles 32 and 33. The solder particles 32 have a larger volume than the solder particles 31 and a smaller volume than the solder particles 33, and have a higher melting point than the solder particles 31 and thus the solder particles 33.
Has a lower melting point. The solder particles 33 have a larger volume than the other two solder particles 31 and 32, and have a higher melting point than the other two solder particles 31 and 32.

Further, similarly to the above-described embodiment described with reference to FIG. 4, the electrodes of the circuit board 4 and the electrodes of the LSI chip 22 are connected by the connecting members formed by solder bumps. The solder bump has a lower melting point than the smallest solder particle 31 and has a smaller volume than the smallest solder particle 31.

As shown in FIG. 5A, the circuit board connecting method using the solder bumps according to the present embodiment is the same as the circuit board 4 described above.
The solder particles 31, 32, 33 are arranged on the top. Figure 5
As shown in (b), the solder particles 31, 32, 33
Is crushed by a press device 21, and then the LSI chip 22 is placed on the crushed solder particles 31, 32, 33.
Is mounted and the circuit board 4 and the LSI chip 22 are connected.

Then, as shown in FIG. 5C, the heater 11 is used at a temperature t ₁ which is higher than the melting point of the smallest solder particle 31 and lower than the melting point of the medium-sized solder particle 32. By heating the solder particles 31, 32, 33 and melting only the smallest solder particles 31, the surface tension of the smallest solder particles 31 causes the LSI chip 22 to be removed from the surface of the circuit board 4.
The height to the back surface of can be h ₁ .

Further, as shown in FIG. 5 (d), at the temperature t ₂ which is higher than the melting point of the solder particles 32 having a medium size and lower than the melting point of the solder particles 33 having a larger size by using the heater 11. The solder particles 31, 32, 33
Is heated to melt the solder particles 32 having the intermediate size and the solder particles 31 having the smallest size, so that the surface tension of the solder particles 32 having the intermediate size causes the LSI chip from the surface of the circuit board 4. The height to the back surface of 22 can be set to h ₂ higher than h ₁ .

Further, as shown in FIG. 5D, the solder particles 31, 32, ₃ are heated by using the heater 11 at a temperature t ₃ higher than the melting point of the solder particle 33 which is the largest.
3 is heated to melt the largest solder particle 33, the medium size solder particle 32, and the smallest solder particle 31. The surface tension of the largest solder particle 33 causes the surface of the circuit board 4 to be melted. The height from to the back surface of the LSI chip 22 can be set to h ₃ higher than h ₂ .

As described above, the three kinds of solder particles 31, 32, 33 are arranged on the circuit board 4, the three kinds of solder particles 31, 32, 33 are crushed, and the three kinds of crushed solder are crushed. LSI chip 22 on particles 31, 32, 33
Is placed and the temperature for heating the three types of solder particles 31, 32, 33 is adjusted, and
The height of the SI chip 22 is adjusted. For example, the optical interconnection of an optical device having a light emitting portion is required to have positional accuracy not only in the parallel direction in the optical device but also in the height direction in the optical device. However, the above-mentioned solder particles 31, 32, 33 are used. By doing so, it is possible to adjust the position in the height direction while monitoring the light amount,
Positional accuracy in the height direction is improved.

Although three types of solder particles 31, 32, and 33 are used in the present embodiment, the types of solder particles used are not limited to three types.

[0051] be described with reference to board connection method in FIG. 6 with solder bumps of an embodiment of the present invention according to claim 8. As shown in FIG. 6C, the substrate connecting structure obtained by the substrate connecting method using the solder bumps of the present embodiment has the first electrode 5 and the second substrate 5 of the circuit board 4 which is the first substrate. Is connected to the second electrode 34 of the LSI chip 22 by the connecting member 35. The connection member 35
Are formed by heating and melting the first solder bumps 36 formed on the first electrode 5 and the second solder bumps 37 formed on the second electrode 34. The connection member 35 is formed so as to be inclined toward the center line A side of the circuit board 4 and the LSI chip 22. The second electrode 34 is formed by being shifted toward the center line A side with respect to the first electrode 5. The LS
The I-chip 22 has a lower coefficient of thermal expansion than the circuit board 4.

In the substrate connecting method using the solder bumps of this embodiment, as shown in FIG. 6A, the first solder bumps 36 and the second solder bumps 37 are formed by the solder particles having the same volume and melting point. Form. Then, the center line A is aligned with the LSI chip 22 facing the circuit board 4, and the second solder bump 37 is brought into contact with the first solder bump 36.

As shown in FIG. 6B, the first solder bump 36 and the second solder bump 37 are heated and melted by the heater 11 to melt the first electrode 5 and the second solder bump 37. The connection member 3 for connecting with the electrode 34
5 is formed.

In this manner, the second electrode 34 is formed by being shifted toward the center line A side with respect to the first electrode 5, and the first solder bump 36 and the second solder bump 37 are heated and melted. By forming the connecting member 35 with, the end portion of the connecting member 35 on the side of the LSI chip 22 can be tilted toward the center line A side. Therefore, a uniform force is applied in the direction in which the LSI chip 22 is spread by each connecting member 35 due to the surface tension of the heated and melted first solder bump 36 and second solder bump 37. Therefore,
After the connection member 35 is formed, the heating is stopped and the connection member 3
When solidifying 5, the circuit board 4 and the LSI chip 22
Shrinks as it cools, but the difference in shrinkage between the circuit board 4 and the LSI chip 22 is reduced, so that the stress applied to the connecting member 35 is relieved and the reliability against thermal fatigue is improved.

[0055]

[0056]

According to the invention of claim 1 , by flattening the solder bump and increasing the diameter of the solder bump,
When connecting another board to the board on which this solder bump is formed, even if the other board to be connected is slightly misaligned, the corresponding electrodes formed on those boards can be connected, so alignment accuracy The yield can be improved because the substrates can be connected to each other even if the value is poor.

According to the second aspect of the present invention, the solder bumps are formed on each of the two substrates, and the diameter of the solder bumps formed on the substrates is increased. Therefore, even if the two substrates are misaligned, the corresponding electrodes formed on the two substrates can be connected to each other, so that the yield is improved.

According to the third aspect of the present invention, the melting point of the second solder bump formed on the second substrate is higher than the melting point of the first solder bump formed on the first substrate. Only the first solder bumps are melted by heating at a temperature lower than the melting point of the second solder bumps, and the melted first solder bumps are fixed around the second solder bumps to form the first substrate and the second substrate. By connecting the first solder bump and the second substrate, the second solder bump can be maintained without being deformed after the first solder bump and the second solder bump are separated from each other.

According to a fourth aspect of the present invention, there is provided a substrate connecting structure in which the first substrate and the second substrate are connected by the substrate connecting method using the solder bumps according to the third aspect, in contrast to the first solder bumps. The first solder bump and the second solder bump are heated at a temperature higher than the melting point and lower than the melting point of the second solder bump to melt only the first solder bump fixed around the second solder bump. By separating the substrate and the second substrate, the second solder bumps can be maintained without being deformed even when the first substrate and the second substrate are separated. Since it is not necessary to re-form the second solder bump when reconnecting with the second substrate, the working process becomes easy.

According to a fifth aspect of the invention, the first solder particles are arranged on the first electrode formed on the first substrate, and the melting point is higher and the volume is larger than that of the first solder particles. The second solder particles are arranged in parallel with the first solder particles on the first substrate, and the first substrate and the second solder particles are crushed by the second substrate, and the first solder particles are The first electrode and the second electrode are connected by heating only the first solder particles by heating at a temperature lower than the melting point of the second solder particles, and the melting point of the second solder particles is higher than that of the second solder particles. By heating and melting the first solder particles and the second solder particles at a high temperature, the surface tension of the second solder particles widens the distance between the first substrate and the second substrate, A contact formed by solder particles that connects the first and second electrodes. Since the length of the portion can be increased, a structure that is strong against thermal strain can be easily obtained, and by crushing the first solder particles, the solder particles that are placed apart from the electrode Since a part spreads on the electrode, when the solder particles are heated and melted, the melted solder particles can be caused to flow out onto the electrodes, and wet bumps can form solder bumps on the electrodes. Formation defects of solder bumps can be prevented, and the yield is improved.

According to a sixth aspect of the present invention, the first solder particles are arranged on the first electrode formed on the first substrate, and the melting point is higher and the volume is larger than that of the first solder particles. The second solder particles are arranged in parallel with the first solder particles on the first substrate, the first solder particles and the second solder particles are crushed, and the first solder particles are replaced by the second solder particles. A solder bump is formed by heating only the first solder particles by heating at a temperature lower than the melting point, and the second electrode formed on the second substrate is brought into contact with the solder bump to form a first electrode and a second electrode. The two electrodes are connected to each other, and the solder bumps and the second solder particles are heated and melted at a temperature higher than the melting point of the second solder particles, and the surface tension of the second solder particles causes the first substrate and the second solder particles to melt. By increasing the distance from the board of
Since it is possible to increase the length of the connecting portion formed by the solder bump and connecting the first electrode and the second electrode, it is possible to easily obtain a structure strong against thermal strain,
Further, by crushing the first solder particles, a part of the solder particles placed apart from the electrode spreads on the electrode, so when the solder particles are heated and melted, the molten solder particles are Since the solder bumps can be formed on the electrodes by wet back, formation defects of the solder bumps can be prevented and the yield is improved.

According to a seventh aspect of the present invention, a plurality of types of second solder particles, the melting points of which increase as the volume increases, are arranged between the first substrate and the second substrate, and the second solder particles are Crushing, the second solder particles are selectively heated and melted, and the surface tension of the melted second solder particles widens the gap between the first substrate and the second substrate, The surface of the second solder particles melted by adjusting the temperature for heating a plurality of second solder particles arranged between the substrate and the second substrate, and selectively melting the second solder particles Since the space between the first substrate and the second substrate can be widened by the tension, the space between the first substrate and the second substrate can be adjusted.

According to the invention of claim 8 , the first substrate is provided with the first electrode and the second substrate is formed so as to be displaced toward the center side as compared with the first electrode. By preparing a second substrate having a lower coefficient of thermal expansion than that, by heating and melting the first solder bumps formed on the first substrate and the second solder bumps formed on the second substrate. By connecting the first electrode and the second electrode, when the solder bumps are heated and melted, the molten solder bumps generate a force to eliminate the inclination toward the center due to the surface tension. Therefore, when connecting the first substrate and the second substrate, the molten solder bumps can suppress the expansion of the first substrate and the second substrate can be expanded, so that the solder bumps can be heated. When stopping and solidifying, It is possible to reduce the difference in shrinkage between the second substrate, the stress applied to the connecting member can be alleviated, thereby improving the reliability against thermal fatigue.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a solder bump forming method according to an embodiment which is a basis of the present invention in the order of steps.

FIG. 2 is an explanatory view showing a solder bump forming method and a substrate joining method using solder bumps according to an embodiment of the invention described in claims 1 and 2 .

FIG. 3 is an explanatory diagram showing a board connecting method using solder bumps and a method of removing the board according to an embodiment of the invention described in claims 3 and 4 .

4 is an explanatory diagram showing a sequence of process steps in a board connection method using a form of the solder bump embodiment of the invention of claim 5 and 6 wherein.

5 is an explanatory diagram showing a sequence of process steps in a board connection method using solder bumps of an embodiment of the invention of claim 7, wherein.

6 is an explanatory diagram showing a sequence of process steps in a board connection method using solder bumps of an embodiment of the present invention according to claim 8.

FIG. 7 is an explanatory diagram showing a conventional solder bump forming method in the order of steps.

FIG. 8 is an explanatory view showing a conventional board connecting method using solder bumps in the order of steps.

[Explanation of symbols]

3 Solder particles 4 substrates 5 electrodes 22 Substrate 23 electrodes 24 solder bumps 25 solder bumps 26 Second solder bump 29 Solder particles 30 solder bumps 31 solder particles 32 solder particles 33 solder particles 34 Second electrode 36 First solder bump 37 Second solder bump

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-306695 (JP, A) JP-A-4-263433 (JP, A) JP-A-63-152136 (JP, A) JP-A-64- 28931 (JP, A) JP 61-159745 (JP, A) JP 2-206138 (JP, A) JP 3-201546 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/60

Claims (8)

(57) [Claims] 1. A solder particle is formed on an electrode formed on a substrate.
Arranging, crushing the solder particles, heating the crushed solder particles to melt
Forming solder bumps method characterized by forming a solder bump on the electrode of the substrate, increasing the diameter of the solder bump by planarizing the solder bump by crushing the solder bumps formed on the substrate by. 2. Preparing two substrates, arranging solder particles on electrodes formed on the substrates, crushing the solder particles, and heating and melting the crushed solder particles.
Forming solder bumps on the electrodes of the substrate by crushing the solder bumps formed on the substrate.
The diameter of the solder bumps is increased by flattening the solder bumps, the solder bumps on one of the substrates are brought into contact with the solder bumps on the other substrate, and at least one of the solder bumps is heated. A substrate connection method using solder bumps, characterized in that the two substrates are connected by melting. 3. A first substrate and a second substrate are prepared , solder particles are arranged on electrodes formed on the substrates, the solder particles are crushed, and the crushed solder particles are heated. To melt
Wherein to form the first solder bumps on the electrode substrate, a second solder bump formed before Symbol second substrate using the first solder particles having a melting point higher than the solder bumps by the first The first solder bump and the second solder bump are brought into contact with each other, and the first solder bump is heated at a temperature lower than the melting point of the second solder bump to melt only the first solder bump. A substrate connecting method using solder bumps, characterized in that the substrate and the second substrate are connected. 4. A first substrate and a second substrate are prepared , solder particles are arranged on an electrode formed on the substrate, the solder particles are crushed, and the crushed solder particles are heated. To melt
Form a first solder bump on the electrode of the substrate by
And has a higher melting point than the first solder bump.
Second solder on the second substrate using solder particles.
A bump is formed, and the first solder bump and the second solder bump are connected to each other.
It brought into contact, melting the first solder bumps of said second solder bumps
Of the first solder bump by heating at a temperature lower than the point
By melting only the first substrate and the second
Connecting the substrate, around the second solder bumps by heating the first solder bumps and the second bumps at the first temperature lower than the higher the second melting point of the solder bumps than the melting point of the solder bumps substrate removal method is characterized in that so as to separate the said second substrate and the first substrate only by melting said first solder bump that is secured to. 5. A first substrate and a second substrate are prepared, first solder particles are arranged on a first electrode formed on the first substrate, and the first solder particles are A second solder particle having a high melting point and a large volume is arranged in parallel with the first solder particle on the first substrate, and the second solder particle and the second solder particle are provided by the second substrate. Crushing the solder particles, the first solder particles by heating the first solder particles at a temperature lower than the melting point of the second solder particles to melt only the first solder particles and the first electrode and the second On the second board
By connecting the formed second electrode, the second by heating and melting the first solder particles and the second solder particles at a temperature higher than the melting point of the second solder particles as in the surface tension of the solder particles increase the distance between the first substrate and the second substrate
A method for connecting a substrate using a solder bump, characterized in that 6. A first substrate and a second substrate are prepared, first solder particles are arranged on a first electrode formed on the first substrate, and the first solder particles are formed from the first solder particles. The second solder particles having a high melting point and a large volume are arranged in parallel with the first solder particles on the first substrate, and the second solder particles and the second solder particles are provided by the second substrate . Crushing the solder particles, to form a solder bump by heating the first solder particles at a temperature lower than the melting point of the second solder particles to melt only the first solder particles, the second The second electrode formed on the substrate of is contacted to the solder bump to connect the first electrode and the second electrode, the solder bump at a temperature higher than the melting point of the second solder particles and The second solder particles are heated and melted. Board connection method using solder bumps, characterized in that widening the distance between the second of said second substrate and the first substrate by surface tension of the solder particles by Rukoto. 7. The second solder particles, wherein a plurality of types of second solder particles having a higher melting point as the volume increases are provided, and the second solder particles are melted by selectively heating and melting the second solder particles. The board connection method using solder bumps according to claim 5 or 6 , characterized in that the distance between the first substrate and the second substrate is widened by the surface tension of. 8. A coefficient of thermal expansion higher than that of the first substrate on which the first electrode is formed and the second electrode formed by being displaced toward the center side from the first electrode. Prepare a second substrate with a low soldering temperature and solder particles on the electrodes formed on the substrate.
Place, crush the solder particles, before crushed
Forming a first solder bump on the first substrate and a second solder bump on the second substrate by heating and melting the solder particles , the first solder bump and the second solder bump And contacting the first solder bump and the second solder bump by heating and melting the second solder bump to connect the first solder bump and the second solder bump.