TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for bonding electric circuit components onto a circuit board, and is applied when mounting the electric circuit parts on a circuit board. It is suitably used for
2. Description of the Related Art In recent years, electric circuit devices such as electric components mounted on a circuit board have been increasingly integrated and miniaturized with the increase in speed of electric signals, and signal wiring has become finer (fine pitch) and the number of pins has been remarkably increased. I have.
Along with this, it is becoming increasingly strict that the mounting method of the electric circuit components on the circuit board is to obtain the connection reliability corresponding to the fine pitch and the increase in the number of pins together with the mounting position accuracy.
At present, as a method of mounting electric circuit components such as a bare chip IC and a ceramic capacitor on a circuit board such as a ceramic substrate for a fine pattern, a silicon substrate, and a glass substrate for a liquid crystal, a bare chip IC uses a wire bonding method, a solder bump, a stud bump. Method, anisotropic conductive film (ACF: Anisotropic Conductive Film), anisotropic conductive paste (ACP: Anisotropic conductive Paste), non-conductive film (NCF: Non-conductive Film), non-conductive paste (NCPnC: NCPNactive: Paste) and the like are used together to implement a COB (Chip On Board) device. 2. Description of the Related Art Among COB devices for mounting ICs, there is a device that melts solder bumps and bonds the ICs to a type corresponding to a work in which ICs are separated.
In the conventional type in which solder bumps are melted and joined, the solder bumps themselves have a self-alignment mechanism, so that the allowable range of parallelism between the substrate and the IC is wide.
The main COB device heats and presses and compresses the IC and the substrate with the upper and lower tools. The upper and lower tools are fixed at one place, and one of the upper and lower tools (for example, the upper tool) is fixed and the other (the substrate) is fixed. There is a multi-location type in which the mounting stage moves. Surface mount type electric circuit components such as ceramic capacitors are also being mounted by ACF, for example, as described in Japanese Patent Application Laid-Open No. 2000-68633, from the reflow method to support fine pitch. This publication proposes a method of interposing an elastic sheet in order to reduce pressure unevenness due to height variations.
[Problems to be solved by the invention]
However, the conventional mounting method has the following problems.
In the case of a COB apparatus, a crimping position fixed type in which the crimping position of the lower tool is one for one upper tool as shown in FIG. 1 and a stage side on which the substrate 5 is mounted as shown in FIG. There is a crimping position movement type in which the crimping position of the lower tool is plural at one moving upper tool. In either case, a mechanism for adjusting the parallelism of the upper and lower tools 1 and 2 provided to uniformly press the bump 4 and the IC 3 in the direction indicated by the arrow 8 (shown by arrows 6 and 7 in FIGS. 1 and 2) At least one of the upper and lower sides.
FIG. 3 shows a state in which the IC 3 is crimped after adjusting the parallelism of the upper tool 1 in accordance with the inclination of the crimping surface of the lower tool 2 in the case of the crimping position fixed type.
However, the first problem of the heating / pressing tool having the parallelism adjusting mechanism is that when the connecting ICs are arranged at a narrow pitch, a large number of ICs cannot be connected at once due to the size and shape of the heating / pressing upper tool. Is a point.
In addition, when the IC is resin-bonded one by one using the above-mentioned adhesive such as ACF or NCP with this apparatus, heat at the time of heat bonding is transmitted to the next IC already bonded, and the bonding by the adhesive is performed by the heat. Loose conduction failure occurs.
The second problem is that, as shown in FIG. 2, when the crimping position of the lower tool is a plurality of crimping position moving types for one upper tool and the upper tool has a parallelism adjusting mechanism, the lower tool is For each crimping position, the upper tool performs the parallelism correction movement to the adjustment position input in advance, but this method also caused an error in the parallelism correction position due to the variation in the repeat position accuracy of the stage. .
A third problem is that, when a plurality of electric circuit components 3 are mounted on one circuit board 5 by a COB device as shown in FIG. 5, warpage in the longitudinal direction of the circuit board occurs. This is remarkable when 8 to 9 thin bare chip ICs having a thickness of 175 μm, a length of 10 mm, and a width of 2.5 mm are mounted on a silicon substrate having a thickness of 780 μm, a length of 100 mm, and a width of about 7 mm, and 40 to 50 μm It has been confirmed that it warps.
This warping not only causes a stress on the device on the circuit board and lowers the reliability of the device itself, but also causes a stress on the bump bonding portion and lowers the bonding reliability.
A fourth problem is that, as shown in FIG. 6, according to the method of pressing the IC 3 via the elastic sheet 9 described in JP-A-2000-68633, the back surface of the IC is inclined with respect to the pressing direction. In such a case, since the rubber 9 to be compressed is pressed unevenly, an uneven pressure distribution occurs, and the amount of crushing of the IC bumps and the connection state become uneven.
Further, as shown in FIG. 7, since the elastic sheet 9 presses the back surface of the IC with a uniform distribution load, a portion where no bump exists in the bump arrangement on the IC is particularly dented, which causes IC warpage. This IC warpage phenomenon is particularly remarkable in a thin IC.
Particularly in the case of resin bonding, if the bonding and mounting are performed in a warped state, the ACF resin deteriorates and softens, and the warped IC tends to return, after a process of applying heat and a reliability test.
Then, as shown in FIG. 8, there is a problem that the bump portion 4a which is greatly crushed at the time of pressure bonding is separated from the substrate 5 and a bonding failure occurs.
Furthermore, the elastic sheet method absorbs the difference in height between adjacent ICs, making it difficult to apply uniform pressure. When there is a difference in height, there is a problem that the elastic sheet does not hit the lower IC after it hits the higher IC first, does not hit, and no load is applied.
The fifth problem is that in the case of joining by soldering, it is necessary to heat the solder to a solder melting temperature of about 205 to 225 ° C. for eutectic solder and 230 to 245 ° C. for lead-free solder. If the temperature exceeds the upper temperature limit of the above parts, the board and parts will be destroyed.
SUMMARY OF THE INVENTION An object of the present invention is to provide a batch joining apparatus that solves the above-mentioned problems with the following configuration.
[Means for Solving the Problems]
In order to solve the above-mentioned problems and achieve the object, a batch bonding apparatus according to the present invention is a bonding apparatus that batch-bonds a circuit board on which a plurality of ICs are mounted. A pressure member having a flatness for simultaneously pressing at least two or more ICs mounted thereon, an elastic member for pressing the pressure member, a pressure receiving member for pressing the elastic member, A batch joining apparatus comprising: a pressurizing force generating section for pressing a pressure receiving member; and a batch joining apparatus comprising an adhesive between an IC and a circuit board.
In addition, a batch bonding apparatus having an intermediate member having an elastic modulus of 1 × 10 10 Pa or more between the IC back surface and the IC pressing member.
In addition, a batch joining device having a heating member.
In addition, a batch joining device having an ultrasonic application section.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 9 is a schematic front view showing a state in which the circuit board 5 on which a plurality of ICs 3 are mounted is bonded together after the ACF 10 is attached.
FIG. 10 is a schematic side cross-sectional view as viewed from the perspective direction 27 in FIG.
The circuit board 5 has a total of 12 ACFs affixed to the IC 3 at six mounting positions and two rows. In this embodiment, the ACF has a thickness of 30 μm manufactured by Sony Chemical Corporation. Next, after the IC 3 was positioned, it was temporarily mounted on the circuit board 5 with a mounting pressure of 5 kg.
The circuit board 5 on which the IC 3 is mounted is installed on a board supporting member 12 having a flatness incorporated in the base block 15.
In the present embodiment, a quartz glass plate having a flatness of λ / 1 (λ = 0.546 μm) is used for the substrate support member 12.
The IC 3 is pressed by the IC pressing member 11 having flatness via the intermediate member 14. The intermediate member 14 prevents the ACF protruding by the pressure from adhering to the pressure member 11. In this embodiment, a SUS304H shim having a thickness of 5 μm is used as the intermediate member.
The pressure member 11 is pressed by the pressure receiving member 16 via the elastic member 13. In the present embodiment, a quartz glass plate having a flatness of λ / 1 (λ = 0.546 μm) is used for the pressing member 11 as in the case of the substrate supporting member 12.
The elastic member 13 is made of fluoro rubber having a thickness of 0.5 mm for heat resistance. The fluoro rubber absorbs the height variation and the inclination variation of the plurality of ICs 3, and enables the one-piece pressing member 11 to perform the collective joining in which the bumps of all the ICs 3 are pressed with substantially the same load.
The pressure receiving member 16 has a built-in oilless bearing 26 and can move up and down in the direction of the pressure receiving member movable direction 25 following the pressure receiving member vertical movement guide 23.
When the IC 3 is not pressurized, it is supported by the pressure receiving member support spring 24 so as not to contact the IC 3.
The pressure receiving member 16 sends the compressed gas 19 into the gas chamber 18 in the gas chamber block 17 and expands the pressurized rubber 21 to move downward to press the IC 3.
The base block 15 supporting the substrate support member 12 and the gas chamber block 17 are fixed by a support post 22 and a lock nut 20.
The pressure of the IC 3 can be first adjusted by the gas pressure to be introduced into the gas chamber. In addition, the load for pressing 31 ICs can be adjusted by the ratio of the area where the pressure receiving member 11 is pressed by the pressing rubber 21 to the back surface of the IC 3.
In the present embodiment, the pressure is applied with 30 kg per IC.
Thereafter, in order to heat and cure the ACF 10 between the circuit board 5 and the IC 3, the above-mentioned pressurized collective joining apparatus was put into a clean oven and cured by heating.
The batch bonding apparatus was placed in a clean oven at room temperature, heated from room temperature to 170 ° C., and when the temperature of the circuit board, the IC, and the batch heating apparatus reached approximately 170 ° C., the power was turned off and naturally cooled.
When the temperature returned to room temperature, the collective bonding apparatus was taken out, and the pressure was released.
As a result of checking the connection resistance value of the IC3 after the bonding, good resistance values were shown at the connection resistance value measurement points of all 12 ICs.
FIG. 11 shows a connection resistance value of one typical IC for each of the conventional example and the present embodiment.
The horizontal axis indicates the names of 12 measurement points in one IC, and the vertical axis indicates the connection resistance value.
In the conventional example, there is a variation of 70 to 180 mΩ, but in the present embodiment, it is stable at 70 to 90 mΩ.
As can be seen from the above results, a plurality of ICs arranged at a narrow pitch can be simultaneously and uniformly pressed, so that the bumps can be uniformly pressed. As a result, a stable connection resistance value was obtained.
In this embodiment, the circuit board 5 uses a silicon substrate having a length of 100 mm and a thickness of 780 μm, and the IC 3 is a thin IC having a thickness of 175 μm, a length of 10.11 mm, a width of 2.64 mm, and 446 bumps. Six rows and 12 rows were used. The gap between ICs is a narrow pitch of 0.77 mm.
In the present embodiment, the base block 15, the pressure receiving member 16, the gas chamber block 17, the pressure receiving member vertical movement guide 23, and the support 22 are made of a SUS material.
Hereinafter, a second embodiment of the present invention will be described.
FIG. 12 is a schematic front view showing that the substrate supporting member 12 having the same flatness as the IC pressing member 11 having the flatness has a structure having the heating element 28.
In the present embodiment, a cartridge heater is used as the heating element 28 and is incorporated in the IC pressing member 11 and the substrate supporting member 12.
A heat insulating member 29 in which a heat insulating member 29 is combined with each of the IC pressing member 11 and the substrate supporting member 12 so that the heat generated can be efficiently transmitted to the IC, the ACF, and the substrate. Zirconia was used.
With this structure, after heating to 170 ° C., the air was cooled by blowing from the side surface, and a good connection resistance value was obtained as a result of performing collective joining.
As for the amount of warpage on the back surface of the IC, good results were obtained with less warpage than the bonding method according to the conventional example. The results are shown in FIGS. FIG. 15 shows an IC back surface warpage measurement point 30. When the IC-side bumps 35 and the circuit board-side bumps 36 are joined and the bump arrangement is not uniform, a portion without bumps is bent.
FIG. 13 shows three warp shapes of the IC. As can be seen from the figure, the bonding according to the conventional example has a maximum back surface warpage of 3 μm.
On the other hand, in the bonding according to the present embodiment in FIG. 14, the amount of back surface warpage was reduced to a maximum of 1.5 μm.
As a result, the amount of deformation of the bumps became uniform, and bonding with higher reliability became possible.
FIG. 16 is a schematic front view showing an embodiment in which a ceramic heater is used as the heating element 28 and the IC body is used as an IC pressing member having flatness. SiC was used for the ceramic heater.
With this structure, the heating / cooling time can be significantly reduced as compared with the case of the cartridge heater. The cartridge heater required 5 minutes of heating and 15 minutes of cooling, whereas the ceramic heater required 1 minute of heating and 3 minutes of cooling.
Even after 100 cycles of a heat cycle test of 80 ° C. × 30 minutes / −30 ° C. × 30 minutes, and after 360 hours of a high-temperature and high-humidity test of 60 ° C./90%, a good connection resistance value is obtained after each reliability test. Maintained.
Also in the present embodiment, the flatness λ / 1 (λ = 0.546 μm) of the IC pressing member 11, the substrate supporting member 12, and the ceramic heater heating element 28 is set.
Hereinafter, a third embodiment of the present invention will be described.
FIG. 17 is a schematic side view using the ultrasonic vibration member 31 as the joining means.
In the present embodiment, a silicon substrate having a length of 300 mm and a thickness of 780 μm is used as the circuit board 5, and an IC 3 having a thickness of 175 μm and a thickness of 10.11 mm, a width of 2.64 mm and a number of bumps of 446 is used as the IC 3. A total of 24 rows were used, 12 rows for 2 rows.
Further, in the present embodiment, since the circuit board 5 is long, the ultrasonic vibration member 31 on the IC side has a structure in which three 100 mm lengths are combined, and 12 ultrasonic vibration members for one row and six rows of ICs are used for one ultrasonic vibration. The member 31 was pressed.
A flatness λ / 1 (λ = 0.546 μm) was set between the IC contact plane of the IC pressing member and the IC-side ultrasonic vibration member and the circuit board contact plane of the substrate supporting member and the substrate-side ultrasonic vibration member.
First, the underfill material 33 is dropped onto the IC mounting position of the circuit board 5.
Next, ultrasonic waves were applied to the circuit board 5 on which the IC 3 was positioned and mounted, and the bumps of the IC 3 and the bumps of the circuit board 5 were metal-to-metal bonded.
The metal-to-metal bonding enables bonding with higher bonding strength than bonding with an adhesive such as ACF.
As for the ultrasonic frequency, when the ultrasonic vibration energy for IC bonding is small, the ultrasonic vibration member may be only on the IC side.
In the present embodiment, since the circuit board 5 is long, a structure in which three pressure members having a length of 100 mm are combined is adopted, so that the circuit board 5 can easily be compared with one pressure member having a length of 300 mm. The factor of the distortion of the sample can be reduced, and uniform collective pressing can be performed.
Also, with respect to the amount of substrate warpage, the amount of warpage can be reduced as compared with the conventional bonding method.
18 and 19 show measurement results of the amount of substrate warpage. FIG. 20 shows a circuit board warpage measuring point 37.
FIG. 18 shows an initial state of a circuit board warpage amount and a state after bonding in a case where bonding according to a conventional example is performed.
The variation from the beginning has increased by about 300 μm.
On the other hand, FIG. 19 shows the initial and post-bonding amounts of the circuit board warpage when the bonding according to the present embodiment is performed.
From this figure, there is almost no variation from the beginning, and a great improvement can be confirmed. By reducing the amount of substrate warpage, the stress applied to the bump bonding portion was reduced, and reliable bonding was made possible.
From the above results, stable electric connection was obtained by uniform collective pressure bonding for a plurality of ICs in two rows with a narrow pitch, and a circuit board with less warpage was realized.
In the above embodiment, the ACF is used, but an ACP, an NCF, or an NCP may be used.
【The invention's effect】
As described above, according to the present invention, when a plurality of ICs are mounted at a narrow pitch, the plurality of ICs are collectively pressurized and heated by using a member similar to a single pressing member having flatness, so that one IC can be mounted. A highly reliable IC bonding with a smaller amount of IC warpage and a smaller amount of circuit board warpage can be realized in a shorter time than the COB method of bonding one by one.
[Brief description of the drawings]
FIG. 1 shows a conventional example of IC mounting using a COB device.
FIG. 2 shows a conventional example of IC mounting using a COB device.
FIG. 3 shows a conventional example of IC mounting using a COB device.
FIG. 4 is a conventional example of IC mounting using a COB device.
FIG. 5 shows a conventional example of IC mounting using a COB device.
FIG. 6 shows a conventional example of IC mounting using a COB device.
FIG. 7 shows a conventional example of IC mounting using a COB device.
FIG. 8 shows a conventional example of IC mounting using a COB device.
FIG. 9 shows a first embodiment of the present invention.
FIG. 10 is a schematic side sectional view seen from the perspective direction in FIG. 9;
FIG. 11 shows connection resistance values of one typical IC for the conventional example and the present embodiment.
FIG. 12 shows a second embodiment of the present invention.
FIG. 13 shows the amount of warpage on the back surface of the IC.
FIG. 14 shows the amount of warpage on the back surface of the IC.
FIG. 15 shows locations where the back surface warpage amount of the IC is measured.
FIG. 16 shows a second embodiment of the present invention.
FIG. 17 shows a third embodiment of the present invention. FIG. 18 shows a measurement result of a substrate warpage amount.
FIG. 19 shows a measurement result of a substrate warpage amount.
FIG. 20 shows a circuit board warpage measurement position.
[Explanation of symbols]
1 upper tool 2 lower tool 3 IC
4 Solder bump 5 Circuit board 8 Pressure direction 9 Elastic sheet 10 Anisotropic conductive film (ACF)
DESCRIPTION OF SYMBOLS 11 IC pressurizing member 12 Substrate support member 13 Elastic member 14 Intermediate member 15 Base block 16 Pressure receiving member 17 Gas chamber block 18 Gas chamber 19 Compressed gas 20 Lock nut 21 Pressurized rubber 22 Column 23 Pressure receiving member vertical movement guide 24 Pressure receiving member support Spring 25 Pressure receiving member movable direction 26 Oil-free bearing 27 Perspective direction 28 Heating element 29 Heat insulating member 30 IC back surface warpage measurement point 31 Ultrasonic vibration member 32 Substrate warpage measurement point 33 Underfill material 34 IC base 35 IC side bump 36 Circuit board side bump 37 Circuit board warpage measurement point