JP2005259925A - Mounting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the mounting method of a chip-shaped electronic component, capable of high reliability junction by restraining the production of an alloy due to intermetallic diffusion. <P>SOLUTION: Before a solder ball 14, formed on the side of an IC chip 10, makes contact with the wiring land 2 of a substrate 1, the solder ball 14 is heated beyond a melting point and melted, and is brought into contact with the wiring land 2 in the molten state. The molten state is kept after the contacting, and then heating is stopped and cooling is applied. Consequently, since jointing time is shortened to restrain alloy formation and proper jointing is made. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a mounting method suitable for mounting electronic components, for example, face down.

  Conventionally, as a terminal connection method of a chip component such as a semiconductor chip, a semiconductor device of a type in which a chip component is die-bonded using Sn—Pb-based eutectic solder or the like as widely used in the manufacture of electronic equipment, for example. In addition, it is applied to a semiconductor device connected by BGA (Ball Grid Array) or CSP (Chip Scale Package) for flip-chip connection of chip components.

  In particular, when flip-chip connection of chip parts is performed, solder bumps are used between the electrodes of the electronic parts and the electrodes of the printed wiring board, commonly referred to as C4 (Controlled Collapse Chip Connection) connection, and are joined by reflow. The method is known.

  FIG. 17 is a schematic diagram showing a process of bonding the electrode 11 on the IC chip 10 side and the wiring land 2 of the substrate 1 using the above-described Sn—Pb eutectic ball called C4.

  That is, as shown in FIG. 17A, solder balls 14 are formed on the electrodes 11 of the IC chip 10 to be mounted, and this is referred to as a printed wiring board (hereinafter referred to as a substrate) using a head (not shown), for example. ) After being positioned above the wiring land 2 of 1, the solder balls 14 are brought into contact with the wiring land 2 as shown in FIG. In addition, although the solder resist and flux etc. exist in the board | substrate 1, illustration is abbreviate | omitted.

  Next, with the solder balls 14 in contact with the wiring lands 2, using a jig for holding the IC chip 10 and the substrate 1 at a predetermined interval, they are carried into a reflow furnace (not shown) and reflowed. As shown in 17 (c), the solder 14 has a fillet shape, and the IC chip 10 and the substrate 1 are joined, so that the IC chip 10 and the substrate 1 can be mounted without applying a load.

  In this case, a Cu stud bump (see FIG. 18 to be described later) is projected from the electrode 11 and the solder ball 14 can be disposed thereon.

  FIG. 18 is a schematic view showing a process of mounting an IC chip on a substrate using an FC (Flip Chip) bonder.

  First, as shown in FIG. 18 (a), the insulating film 3 is partially arranged and coated on the wiring 2A on the surface of the substrate 1 by pattern printing to form an uncoated land 2; As shown in b), UF (underfill) resin 4 is dropped between lands and on lands 2.

  Next, as shown in FIG. 18 (c), Cu stud bumps 12 are provided on the electrodes 11 of the IC chip 10 to be mounted, and solder balls 14 are formed thereon, and the IC chip 10 is heated by the heater 9. The solder ball 14 is heated to 80 ° C. by being held by the suction head 8, placed in this state above the substrate 1, and lowered while being aligned.

  Next, as shown in FIG. 18 (d), the solder ball 14 is pushed into the fluid UF resin 4 while being pressurized (several tens of grams per pin) by the suction head 8, and the solder ball 14 is inserted into the wiring land. 2, the suction head 8 is heated to 220 ° C. to 250 ° C. by a heater 9 provided in the suction head 8, and the solder balls 14 on the electrodes 11 of the IC chip 10 held by the suction head 8. As shown in FIG. 19E, the molten state of the solder 14 is maintained for 2 seconds, for example. Further, the UF resin 4 is also cured by this heating. A camera or the like is used to detect such contact of the solder balls 14.

  Next, as shown in FIG. 19 (f), the heating of the solder 14 by the suction head 8 is stopped, and the solder 14 is cooled and solidified by blowing, for example, cold air, whereby the electrode 11 of the IC chip 10 is connected to the wiring of the substrate 1. Coupled to land 2. Then, after cooling to about 150 ° C., the head is detached as shown in FIG.

  FIG. 20 is a graph showing the relationship between the time required for each step and the solder temperature in the above-described process.

  That is, the solder 14 is heated after contacting the wiring land 2 of the substrate 1 while being heated to 80 ° C., heated to 220 ° C. in 8 seconds and melted, and this molten state is held for 2 seconds, and then heated. Then, the electrode 11 of the IC chip 10 and the wiring land 2 of the substrate 1 are combined. When the temperature is lowered to about 150 ° C., the head 8 is detached. Accordingly, the diffusion phenomenon between the metals is maintained during the period from the temperature rise to the melt holding time (10 seconds).

  In other words, as described above, this bonding method is performed by the metal diffusion bonding and the UF between the Cu bump 12 and the wiring land 2 accompanying the heat melting of the solder 14 after the solder ball 14 and the wiring land 2 of the substrate 1 are in contact with each other. The fixing force by the resin 4 is used.

  Regarding such IC chip mounting technology, the solder bumps provided on the chip side are heated to a temperature lower than the melting point temperature of the solder, and the solder bumps are contacted while being plastically deformed by pressing between the chip and the substrate. After that, it is disclosed that the solder bumps are heated to the melting point temperature or more and are connected by the pressure of only the weight of the chip (see the patent document described later).

Japanese Patent No. 3198555 (page 1, column 1, lines 6-12, page 2, column 4, lines 21-26 and page 3, column 5, lines 12-15), FIG. 1)

  However, in the conventional mounting method shown in FIG. 17, the distance between the solder ball 14 and the wiring land 2 when the solder ball 14 or the wiring land 2 on the IC chip 10 side has a height variation or warpage. Is not uniform, it is difficult to bond at all the connecting portions, and a long bonding time is required.

  Further, in the conventional mounting method shown in FIGS. 18 to 19, in order to bring all the solder balls 14 on the IC chip side into contact with the wiring lands 2 of the substrate 1 at the time of bonding, and to promote diffusion bonding between metals, A considerably large load is required at the time of bonding, and the IC chip 10 is easily damaged by this pressurization.

  In other words, since a load of several tens of grams is applied to each solid solder ball 14 before melting at the time of contact and comes into contact with the wiring land 2, the thin IC chip 10 receives pressure from below through the solder ball 14, and this Since stress due to pressure is generated, the low-k film on the chip surface is damaged, cracks are likely to occur at the interface, and the bonding time is long.

  As a result, as shown in FIG. 21 (enlarged view of the vicinity of the single electrode 11 of the IC chip 10 and the single wiring land 2 of the substrate 1), the Cu stud bump 12 on the chip electrode 11 and the substrate Bonded by forming an alloy layer 15 by diffusion of metal atoms between the Cu layer 5, the Ni (nickel) layer 6, and the Au (silver) layer 7 constituting the wiring land 2, as indicated by arrows. However, if the joining time is long, the resulting alloy layer 15 becomes thick and the joint becomes brittle.

  When such a joint is subjected to a temperature cycle test (acceleration test) between −25 ° C. and 125 ° C., cracks occur 1000 times.

  Thus, in any of the above, since the time required for bonding is long, a brittle intermetallic compound is formed at the bonded portion. Therefore, there is a concern that this intermetallic compound reduces the reliability of bonding. However, in Patent Document 1 described above, since the solder is heated at the melting point for a longer time (5 to 30 seconds), the intermetallic compound becomes thicker and a good joint cannot be obtained.

  Therefore, an object of the present invention is to provide a mounting method capable of forming a highly reliable bond in a short time by suppressing alloy formation due to diffusion between metals.

That is, the present invention
In a non-contact state where the electronic component and the mounting substrate are not in contact with each other, a conductive low melting point bonding material is disposed on either the electronic component or the mounting substrate, and the low melting point bonding material is brought to a temperature equal to or higher than the softening point. Heating, and
Bringing the electronic component and the mounting substrate into contact with each other under the heating temperature;
Holding the low melting point bonding material in a molten state after this contact;
And a step of solidifying the low melting point bonding material by lowering the temperature from the molten state (hereinafter referred to as a mounting method of the present invention).

  According to the mounting method of the present invention, the low melting point bonding material is heated to a temperature equal to or higher than the softening point before contact between the electronic component and the mounting substrate, and in this state, the electronic component and the mounting substrate are brought into contact with each other. The low melting point bonding material can be held in a molten state by being brought into contact without being applied, and further cooled to be solidified.

  As a result, even if there is a variation in the height of the low melting point bonding material and / or the height of the mating material without causing damage to the electronic components, it is possible to reliably bond, shortening the heating time required for the bonding, Generation of intermetallic compounds can be suppressed and thermal deformation of the mounting substrate can also be reduced.

In the mounting method described above, the low-melting-point bonding material is heated and melted in the non-contact state, and the electronic component and the mounting substrate are brought into contact with each other in the molten state, or in the non-contact state. Heating and softening the low-melting-point bonding material and keeping the electronic component and the mounting substrate in contact with each other in this softened state can save or shorten the temperature rise time of the low-melting-point bonding material after the contact. Desirable in terms.

  In this case, a bump is formed by covering the electrode of the electronic component with the low melting point bonding material, and after heating at least the uppermost layer of the bump to the softening point or higher, the bump is applied to the wiring land of the mounting substrate. It is desirable to contact.

  And it is desirable to hold | maintain the said electronic component in a holder, and to heat more than the said softening point from this holder.

  In this case, it is preferable that the holder holding the electronic component is detached from the electronic component after the low melting point bonding material is solidified.

  In addition, it is preferable that an underfill material is attached in advance on the mounting substrate, and the electronic component on which the low melting point bonding material is disposed is brought into contact with the mounting substrate.

  Further, heating above the softening point may be performed from the mounting substrate.

  Further, as the electronic component, a chip-shaped electronic component or a wafer to be separated into chip-shaped electronic components is used, and when this wafer is used, the wafer is chip-shaped after the solidification of the low melting point bonding material. It can also be separated into electronic parts.

  In addition, it is desirable that at least one of the electronic component and the mounting board be provided with sensor means for detecting the contact, because pressure due to contact can be prevented.

  In this case, it is desirable to project the sensor means on the electronic component, and to detect that the sensor means has contacted the mounting substrate, and to determine the position at the time of contact between the electronic component and the mounting substrate. .

  Here, the above “conductive low melting point bonding material” is a low melting point metal such as solder, for example, Sn—Pb, Sn—Ag, Sn, Pb, In, Sn—Ag—In, etc. A material having a low melting point and capable of forming an alloy joint with a conductive counterpart.

  Next, the preferred embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1
1 and 2 are schematic diagrams showing the mounting process of the present embodiment, but the basic process is the same as the conventional example (FIGS. 18 and 19) already described.

  That is, first, as shown in FIG. 1A, an insulating film 3 is partially arranged on a wiring 2A on the surface of a substrate 1 by pattern printing and covered to form an uncovered land 2; As shown in 1 (b), the UF resin 4 is dropped between lands and on the lands 2.

  Next, as shown in FIG. 1 (c), Cu stud bumps 12 are provided on the electrodes 11 of the IC chip 10 to be mounted, solder balls 14 are formed thereon, and the IC chip 10 is heated by the heater 9. The solder ball is heated to 80 ° C. by being held by the suction head 8, and the IC chip in this state is disposed above the substrate 1.

  Next, as shown in FIG. 1 (d), before the solder balls 14 contact the wiring lands 2, the temperature of the head 8 is raised to 220 ° C. to 250 ° C. with the heater 9 provided in the suction head 8. The balls 14 are heated to melt the solder balls 14 on the stud bumps 12. In this case, in order to prevent the molten solder from being oxidized, bonding in a nitrogen atmosphere is desirable.

  Next, as shown in FIG. 2E, the IC chip in which the solder balls 14 are in the molten state is lowered and brought into contact with the substrate 1. Accordingly, the molten solder ball 14 comes into contact with the wiring land 2 of the substrate 1 without applying pressure while repelling the fluid UF resin 4 having a lower viscosity than that. Accordingly, the UF resin 4 is also heated and cured. In this case, it is important to lower the IC chip 10 beyond the variation range in consideration of variations in the heights of the solder balls 14 and the wiring lands 2 of the substrate 1.

  Next, as shown in FIG. 2G, the heating of the solder 14 by the suction head 8 is stopped, and for example, cold air is blown to cool and bond the solder 14. After cooling to about 150 ° C., the suction head is detached as shown in FIG. After mounting, the suction head 8 holds the next IC chip in an uncooled state (about 180 ° C.), so that the solder ball can be melted quickly. In these cases, the number of chips held by the suction head 8 can be 1 chip / 1 head or a plurality of chips / 1 head. The same applies to other embodiments and modifications described later.

  As described above, the feature of this embodiment is that, unlike the conventional example described above (see FIGS. 18 and 19), the solder ball 14 is heated and melted after contacting the wiring land 2. 14 is brought into contact with the wiring land 2 in a molten state by heating and melting before contacting. As a result, no cracks occurred in the joint even in 1000 temperature cycle tests (acceleration test) between −25 ° C. and 125 ° C.

  FIG. 3 is a graph showing the relationship between the time required for each step and the solder temperature in the present embodiment.

  That is, since the solder ball 14 is heated to 220 ° C. and comes into contact with the wiring land 2 of the substrate 1 in a molten state, the time required for temperature rise and melting after the contact is saved. After the contact, the molten state is maintained for 2 seconds, and then the heating is stopped and the mixture is cooled for 2 seconds to bond. Then, after the temperature is lowered to about 150 ° C., the suction head 8 is detached. Therefore, in this case as well, it takes time to raise the temperature of the solder ball 14 to the melting point temperature. However, since the temperature is raised in the air in a non-contact state, the post-contact process is shorter than in the conventional case where the temperature is raised after contact. In time, the time for the diffusion phenomenon between metals can be greatly shortened.

  As a result, as shown in FIG. 4 (corresponding to FIG. 21 in the conventional example), the Cu stud bump 12 on the chip electrode 11, the Cu layer 5 and the Ni layer 6 and the Au layer 7 constituting the wiring land 2 As shown in the figure, the alloy layer 15 can be formed thinner than in the prior art (FIG. 21).

  FIG. 5 shows an enlarged view exaggerating a single unit after the above-described IC chip 10 is separated. That is, the shape of the IC chip 10 before mounting is clearly shown. Thus, the stud bump 12 made of Cu protrudes from the chip electrode 11, and the solder ball 14 is formed at the tip of the stud bump 12. Is formed. However, this stud bump may not be present.

  FIG. 6 shows a detailed view of the structure of the suction head 8. That is, the main body of the suction head 8 made of ceramic is composed of a lower part 8a and an upper part 8b, the upper part 8b has a hollow part 18, and the lower part 8a is formed with a plurality of intake holes 13 (illustrated in this figure). Has been. The IC chip 10 is sucked by the suction head 8 by evacuating the upper portion 8b shown in a simplified manner by a suction mechanism (not shown).

  Then, a heater 9 is formed in the lower portion 8 a by wiring passing through the wall portion of the upper portion 8 b, and the heat of the heater 9 is transmitted to the IC chip adsorbed and held by the head 8 to heat the solder balls 14. The heater 9 can raise the temperature of the suction head 8 to 400 ° C., and the ceramic has a heat storage function, so that the solder ball 14 can be heated satisfactorily. Moreover, since the temperature of the solder ball 14 on the IC chip 10 being sucked is lower by about 30 ° C. than the temperature of the suction head 8, the solder ball 14 can be heated to a desired temperature by using this temperature difference as a guide.

According to the present embodiment, the solder ball 14 is heated by the suction head 8, the solder ball 14 is melted before the solder ball 14 contacts the wiring land 2, and the solder ball 14 is contacted in the molten state. Such a remarkable effect can be exhibited.
1. Since it is not necessary to use a reflow furnace, the substrate 1 is not warped.
2. Bonding is possible without applying pressure during bonding, and the IC chip 10 is not damaged.
3. The variation in the heights of the solder balls 14 and the wiring lands 2 can be absorbed and uniform bonding can be achieved.
4). By shortening the time required for joining, it is possible to suppress the formation of alloys at the joint. As a result, since the heat transmitted to the substrate side is small, the substrate 1 is not warped.

Embodiment 2
FIG. 7 is a graph showing the relationship between the time required for each step and the solder temperature according to the present embodiment, and corresponds to the graph (FIG. 3) in the first embodiment described above.

  This embodiment is the same as the first embodiment except that the temperature of the solder ball 14 when the solder ball 14 is brought into contact with the wiring land 2 is the same as that of the first embodiment. This will be described with reference to a part of FIG.

  That is, in the process of FIG. 1D, in the first embodiment, the solder ball 14 is heated to 220 ° C. to be in a molten state, but in the present embodiment, the solder ball 14 has a softening point of 150. It softens by heating to ° C., and in this softened state, the solder balls 14 are brought into contact with the wiring lands 2 as shown in FIG. Then, after this contact, the temperature is raised to 220 ° C. to melt the solder ball 14, and thereafter, after the melting and holding time of 2 seconds, the heating is stopped and the cooling is performed for 2 seconds as in the first embodiment. Then, the suction head 8 is detached. Also in this case, since the suction head 8 is in an uncooled state, the solder ball of the IC chip to be gripped next can be softened quickly.

  Therefore, according to the present embodiment, the solder ball 14 is heated in advance to the temperature of the softening point, and then brought into contact with the wiring land 2, and then the solder is heated to the melting point temperature. Therefore, since the time required for joining can be shortened as compared with the conventional example (FIG. 20), a remarkable effect can be exhibited in substantially the same manner as in the first embodiment, and only the softening is achieved. There is no fear that the solder 14 will sag, the adjacent solder balls 14 do not come into contact with each other, and therefore, handling is easy, and there is an advantage that a nitrogen atmosphere is not required for preventing oxidation of the solder. .

  Hereinafter, modifications of the above-described embodiments will be described.

  FIG. 8 is a modification showing a method of forming the solder balls 14 brought into contact with the wiring lands 2 into a better fillet shape.

  FIG. 8 (a) (corresponding to FIG. 2 (e)) is obtained by bringing the molten solder ball 14 into contact with the wiring land 2 and then lifting the suction head 8 slightly upward as indicated by the arrow. As shown in FIG. 8B, the solder 14 in a molten state follows and deforms, and can be formed into a fillet shape in which the lower part is well spread.

  9 and 10 show a modification of the method for detecting the contact of the solder ball 14 to the wiring land 2.

  Although a camera is used for detection in the above-described embodiment, detection may be performed using sensor means as shown in FIG.

  FIG. 9 shows the electronic component 25 in a wafer state before, for example, separation into individual pieces, and is a view in which the contact sensor 17 is fixedly installed on one edge thereof. The tip of the contact sensor 17 protrudes from the Cu stud bump 12 and is at a position lower than the height of the solder ball 14. The sensor 17 after mounting may be left.

  FIG. 10A shows an enlarged view of a part (sensor side) of FIG. 9 held by the suction head 8 and is mounted on the substrate 1. Accordingly, by lowering the suction head 8, the solder ball 14 contacts the wiring land 2 while repelling the UF resin 4 as shown in FIG. 10B, and the tip of the contact sensor 17 contacts the wiring land 2. By doing so, the contact position of the electronic component 25 and the board | substrate 1 can be determined.

  FIG. 11 and FIG. 12 show a modification using a thermosetting resin (for example, epoxy resin) instead of the UF resin 4 in the first embodiment. Therefore, since this resin is substantially the same as that of the first embodiment, the process basically similar to that of the first embodiment will be described with reference to FIGS. 11 and 12 (corresponding to FIGS. 1 and 2).

  That is, as shown in FIG. 11 (a), as in the first embodiment, the insulating film 3 is partially arranged by pattern printing on the wiring 2A on the surface of the substrate 1 and covered so that there is no covering. The land 2 is formed, and then a thermosetting resin 19 is dropped between the wiring lands 2 and 2 as shown in FIG.

  Next, as shown in FIG. 11C, similarly to the first embodiment, Cu stud bumps 12 are provided on the electrodes 11 of the IC chip 10 and solder balls 14 are formed thereon, and this IC chip 10 is heated. The solder ball is heated to 80 ° C. with the suction head 8 heated by 9, and the IC chip 10 in this state is placed above the substrate 1.

  Next, as shown in FIG. 11 (d), before the solder balls 14 come into contact with the wiring lands 2, the head 8 is heated to 220 ° C. to 250 ° C. by the heater 9 provided in the suction head 8 and soldered. The balls 14 are heated to melt the solder balls 14 on the stud bumps 12. In this case as well, joining in a nitrogen atmosphere is desirable to prevent oxidation of the molten solder.

  Next, as shown in FIG. 12 (e), the IC chip in which the solder balls 14 are melted is lowered and brought into contact with the substrate 1. As a result, the molten solder balls 14 can be brought into contact with the wiring lands 2 of the substrate 1 without applying pressure. Accordingly, the resin 19 is heated and cured while being filled between the IC chip 10 and the substrate 1 and functions as a fixing material. Also in this case, it is important to lower the IC chip 10 beyond the variation range in consideration of the height variation of the solder ball 14 and the wiring land 2 of the substrate 1.

  Next, as shown in FIG. 12F, after the above contact, the molten state of the solder 14 is held, for example, for 2 seconds as in the first embodiment.

  Next, as shown in FIG. 12G, the heating can be performed by stopping the heating of the solder 14 by the suction head 8 and cooling the solder 14 by blowing cold air, for example. Then, after cooling to about 150 ° C., the suction head is detached as shown in FIG.

  In this case, the fixing force between the IC chip 10 and the substrate 1 is further increased by placing the substrate 1 on a heating stage (not shown) and using the heating by the heating stage and the heating from the suction head 8 together. Can do. In this case, there is no problem because the epoxy resin 19 has a large heat capacity and is heated for a short time.

  13 and 14 are different from the first embodiment and the modified example in which the solder ball 14 is provided on the electrode 11 side of the IC chip 10, and the solder ball 14 is arranged on the wiring land 2 side of the substrate 1. The UF resin 4 and the like are modified examples in that they are provided after mounting. Accordingly, in this case as well, except for the differences, this embodiment is substantially the same as the first embodiment, and will be described with reference to FIGS. 13 and 14 (corresponding to FIGS. 1 and 2) which are basically the same as the first embodiment.

  That is, as shown in FIG. 13 (a), similarly to the first embodiment, the insulating film 3 is arranged on the wiring 2A on the surface of the substrate 1 by pattern printing and partially covered, so that there is no covering. The land 2 is formed, and then solder balls 14 are formed on the wiring land 2 as shown in FIG. In this case, the substrate 1 is disposed on the heating stage 30.

  Next, as shown in FIG. 13C, Cu stud bumps 12 are provided on the electrodes 11 of the IC chip 10 to be mounted. Then, the IC chip 10 is held by the suction head 8 and disposed above the substrate 1.

  Next, as shown in FIG. 13D, the substrate 1 is heated by raising the temperature of the heating stage 30 to 230 ° C. to 240 ° C. for several seconds, and the heat of the substrate 1 is applied to the solder balls 14 on the wiring lands 2. Is heated to the melting temperature and melted.

  Next, as shown in FIG. 14E, the IC chip is lowered and brought into contact with the substrate 1. Accordingly, the stud bumps 12 of the IC chip 10 are immersed in the molten solder balls 14 and can be brought into contact with the wiring lands 2 of the substrate 1 without applying pressure.

  Next, as shown in FIG. 14F, after the above contact, the molten state of the solder 14 is held for 2 seconds, for example.

  Next, as shown in FIG. 14G, the heating of the solder 14 by the heating stage 30 is stopped, and the solder 11 is cooled by blowing, for example, cold air, so that the electrode 11 and the wiring land 2 can be coupled. . Then, after cooling to about 150 ° C., the suction head is detached as shown in FIG. Therefore, the substrate 1 does not warp because it does not reflow. In this case, UF resin may be injected between the IC chip 10 and the substrate 1 after bonding.

  FIG. 15 shows still another modified example. Thus, the IC chip 10 can be mounted at the wafer 20 level before being separated into individual pieces. In this figure, the wafer 20 is shown in a perspective view, and the substrate 1 is shown in a sectional view. Then, the wafer 20 is mounted in the direction of the arrow.

  FIG. 16A is a schematic cross-sectional view of the substrate 1 and the wafer 20 after mounting. In this case as well, stud bumps (not shown) are provided on the electrodes 11 of the respective chip regions arranged on the wafer 20 as in the first embodiment described above. Form solder balls. Then, after the solder balls are heated and melted in advance, the solder balls are bonded to the wiring lands 2 of the substrate 1 through a melting and holding time, a cooling and a solidifying process. That is, the same process as in the first embodiment may be performed. Similarly to the second embodiment, the solder ball can be mounted by the same process as the second embodiment after being softened at the softening point temperature.

  In FIG. 16A, the substrate 1 is exaggerated in a warped shape. However, even when the substrate 1 is warped and the distance between the substrate 1 and the wafer 20 is not uniform, the first embodiment described above is used. Alternatively, by applying the mounting method 2, good bonding can be performed with the solder 14 as illustrated.

  Thus, when mounted on the wafer 20 level, as shown in FIG. 16B, it can be separated into pieces after mounting. In other words, in the figure, the position of the cutting line 20 is cut by the cutter 23 in units of chips of the wafer 20, and for example, the MCM can be configured by dividing into pieces in units of one chip or two chips.

  Each of the above-described embodiments and the like can be variously modified based on the technical idea of the present invention.

  For example, Embodiment 1 or 2 can be combined with each modification, and the process and conditions of Embodiment 1 or 2 can be changed as appropriate. The same applies to.

  Moreover, although each embodiment and each modification demonstrated the IC chip as the object of mounting, you may apply to mounting of electronic components other than IC chip other components.

  The means for heating and melting the solder balls 14 is not limited to the suction head 8 and the heating stage 30 described above, and may be appropriate, for example, heating with a torch or hot air.

It is the schematic which shows the mounting process by this Embodiment 1. FIG. It is the schematic which shows a mounting process same as the above. 4 is a graph showing the joining time and solder temperature in the first embodiment. It is the schematic which shows the diffusion state between metals in embodiment similarly. It is a schematic enlarged view of an IC chip. It is a graph which shows the joining time and solder temperature in Embodiment 2 of this invention. It is the schematic which shows a modification. It is the schematic which shows a modification. It is the schematic which shows a modification. It is the schematic which shows the mounting process by a modification. It is the schematic which shows the mounting process by a modification. It is the schematic which shows the mounting process by a modification. It is the schematic which shows the mounting process by a modification. It is the schematic which shows the mounting process by a modification. It is the schematic which shows a modification. It is the schematic which shows a modification. It is the schematic which shows the mounting process by a prior art example. It is the schematic which shows the mounting process by a prior art example. It is the schematic which shows the mounting process by a prior art example. It is a graph which shows the joining time and solder temperature in a prior art example. It is the schematic which shows the diffusion state between metals in a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Wiring land, 2A ... Wiring, 3 ... Insulating film,
4 ... UF (underfill) resin, 5 ... Cu layer, 6 ... Ni layer, 7 ... Au layer,
8 ... Adsorption head, 8a ... Lower part, 8b ... Upper part, 9 ... Heater, 10 ... IC chip,
DESCRIPTION OF SYMBOLS 11 ... Electrode, 12 ... Stud bump, 13 ... Intake hole, 14 ... Solder ball or solder,
15 ... alloy layer, 17 ... sensor, 18 ... hollow part, 19 ... resin, 20 ... wafer,
22 ... cutting line, 23 ... cutter, 25 ... electronic component, 30 ... heating stage

Claims (12)

In a non-contact state where the electronic component and the mounting substrate are not in contact with each other, a conductive low melting point bonding material is disposed on either the electronic component or the mounting substrate so that the low melting point bonding material is at a temperature equal to or higher than the softening point. Heating, and
Bringing the electronic component and the mounting substrate into contact with each other under the heating temperature;
Holding the low melting point bonding material in a molten state after this contact;
And a step of cooling the molten state to solidify the low-melting-point bonding material.   The mounting method according to claim 1, wherein the low-melting-point bonding material is heated and melted in the non-contact state, and the electronic component and the mounting substrate are brought into contact with each other in the molten state.   The mounting method according to claim 1, wherein the low-melting-point bonding material is heated and softened in the non-contact state, and the electronic component and the mounting substrate are brought into contact with each other in the softened state.   A bump is formed by covering the low melting point bonding material on the electrode of the electronic component, and after heating at least the uppermost layer of the bump to the softening point or higher, the bump is brought into contact with a wiring land of the mounting substrate. The mounting method according to claim 1.   The mounting method according to claim 1, wherein the electronic component is held by a holder, and heating is performed at or above the softening point from the holder.   The mounting method according to claim 5, wherein after the low-melting-point bonding material is solidified, the holder that holds the electronic component is detached from the electronic component.   The mounting method according to claim 1, wherein an underfill material is attached in advance on the mounting substrate, and the electronic component on which the low melting point bonding material is disposed is brought into contact with the mounting substrate.   The mounting method according to claim 1, wherein heating at or above the softening point is performed from the mounting substrate.   The mounting method according to claim 1, wherein a chip-shaped electronic component is used as the electronic component.   The mounting method according to claim 1, wherein a wafer to be separated into chip-shaped electronic components is used as the electronic component, and the wafer is separated into chip-shaped electronic components after the solidification of the low melting point bonding material.   The mounting method according to claim 1, wherein at least one of the electronic component and the mounting substrate is provided with sensor means for detecting the contact.   12. The sensor means is provided so as to protrude from the electronic component, and the position at the time of the contact between the electronic component and the mounting board is determined by detecting that the sensor means has contacted the mounting board. Implementation method.

Images