JP5273017B2 - Method for manufacturing flip mounted body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve productivity in the method of manufacturing of a flip mounting structure as a circuit board to which bare chips are flip-mounted. <P>SOLUTION: The method of manufacturing flip mounting structure includes a step of coating respective mounting regions of a wiring board to which a plurality of mounting regions for flip-chip mounting the bare chips are prepared with an under-fill material paste, a step of respectively conducting the pressure-bonding of the bare chips on the wiring board via the under-fill material after the alignment process and the tentative fixing of the bare chips for half-curing of the under-fill material with heat treatment to the mounting region, and a step of pressing the wiring board with a pressing means from the upper and lower directions in order to press simultaneously the plurality of bare chips on the wiring board to the wiring board side and shifting the under-fill material to the curing state from the semi-curing state through heat treatment. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a flip package, which is a circuit board on which a bare chip is flip mounted, and more particularly, to a method for manufacturing a flip package in view of improving productivity.

  When flip-mounting a bare chip on a wiring board, it is common to provide a resin (so-called underfill resin) between the IC chip and the wiring board in order to improve the reliability of electrical and mechanical connections. Is. This resin is obtained by curing a paste-like, liquid, or semi-cured state during production. Therefore, the process of hardening by heating etc. is essential, and the time required for the process (tact time) is required as compared with the case of simple solder mounting.

  In the field of wiring boards, in recent years, in order to improve production efficiency, a method has been adopted in which a single substrate is manufactured by attaching the same product to multiple faces. In the case of such a multi-sided substrate, if the IC chip is to be flip-mounted as described above corresponding to each product before being singulated, the mounting process takes a very long time depending on the number of mounted IC chips. It becomes such a thing. Depending on the number of implementations, it may take time that is not practical.

  The following Patent Document 1 discloses a method in which an underfill resin can be cured at once for a plurality of IC chips by microwaves. If this is applied, it is considered that many flip mounting processes can be performed in a practical time even in the case of a multi-sided substrate. However, if the device for performing microwave heating is compatible with a large number of IC chips, it is necessary to configure the device as a dedicated device, and the alignment of the IC chip on the substrate is handled by a conventional bonder. Therefore, it is conceivable that the underfill material is deformed before the microwave heating, and there is a concern that the reliability is lowered due to the mounting position shift of the IC chip.

  Patent Document 2 below discloses a method for curing an underfill resin that can be applied to a plurality of IC chips at once using a film-like underfill material. However, the film-like underfill material has disadvantages that it is expensive, difficult to handle and requires a long time for the pasting process, as compared with the paste-like underfill material.

Japanese Patent Laying-Open No. 2004-31902 (FIG. 4) Japanese Patent Laying-Open No. 2005-32952 (FIG. 2)

  The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to improve productivity in a manufacturing method of a flip mounted body which is a circuit board on which a bare chip is flip mounted.

  In order to solve the above-described problems, a method for manufacturing a flip package according to one aspect of the present invention includes a paste-like underlayer on each of the mounting regions of a wiring board in which a plurality of mounting regions on which a bare chip is to be flip-mounted are prepared. For each of the mounting regions, a step of applying a fill material, and a bare chip temporary fixing that aligns and presses the bare chip on the wiring board through the underfill material and heats and semi-hardens the underfill material. And a step of pressing the wiring board from above and below with a pressing means so as to collectively press a plurality of bare chips on the wiring board against the side of the wiring board, and heating the semi-cured underfill material. And a step of shifting from a state to a cured state.

  That is, in this manufacturing method, a paste-like underfill material is used, and bare chip temporary fixing for semi-curing the paste is performed for each bare chip mounting region on the wiring board. By staying in the semi-curing stage in this way, a significant reduction in the process time performed in series for each bare chip is obtained. Thereafter, the plurality of bare chips on the wiring board are collectively pressed and heated by a pressing means. Thereby, the underfill material is collectively shifted from the semi-cured state to the cured state, and the flip mounting is completed. The more bare chips to be mounted, the higher the effect of shortening the mounting time.

  According to the present invention, the productivity can be improved in the method of manufacturing a flip mounted body which is a circuit board on which a bare chip is flip mounted.

The perspective view which shows the example of a structure of the wiring board which can apply the manufacturing method of the flip mounting body which concerns on one Embodiment of this invention. The block diagram which shows the state after application | coating of an underfill material in the application of the manufacturing method of the flip mounting body which concerns on one Embodiment of this invention in a partial cross section. The process figure which shows the aspect of the underfill material application | coating which is one process of the manufacturing method of the flip mounting body which concerns on one Embodiment of this invention with a perspective view. The block diagram which shows the state after bare chip | tip temporary fixation under application of the manufacturing method of the flip mounting body which concerns on one Embodiment of this invention in a partial cross section. The process figure which shows the aspect of the bare chip temporary fixing which is one process of the manufacturing method of the flip mounting body which concerns on one Embodiment of this invention with a perspective view. FIG. 6 is a diagram showing the relationship between the flip chip bonder head and the bare chip in the bare chip temporary fixing step shown in FIG. 5. The graph which shows the example of the temperature characteristic of the viscosity in the underfill material shown in FIG. 2, FIG. The process figure which shows the aspect of the underfill material hardening transfer which is one process of the manufacturing method of the flip mounting body which concerns on one Embodiment of this invention with a perspective view. Explanatory drawing which shows the process of underfill material hardening transfer process shown in FIG. 8 in a partial cross section. The table | surface which shows the flip mounting time at the time of applying the manufacturing method of the flip mounting body which concerns on one Embodiment of this invention in contrast with the case of a comparative example. Sectional drawing which shows the structure of the component built-in wiring board which used the flip mounting body obtained by application of the manufacturing method of the flip mounting body which concerns on one Embodiment of this invention for a member. FIG. 12 is a process diagram illustrating a final lamination process for manufacturing the component built-in wiring board illustrated in FIG. 11.

  As an embodiment of the present invention, the pressing means has a first heating means at a pressing portion that presses the side where the bare chip exists, and a second heating means at the pressing portion that presses the side where the bare chip does not exist And the first heating means has a larger heat generation capacity than the second heating means. As for the heating means provided in the pressing part of the pressing means, the heating to the underfill resin is more effective when the pressing part that presses the side where the bare chip is present has a larger heat generation capacity. This is because the bare chip has higher thermal conductivity than the wiring board. Moreover, since the wiring board is inferior in heat resistance to the bare chip, this configuration is also preferable in this respect.

  Further, as an embodiment, the pressing means has a heating means in a pressing portion that presses the side on which the bare chip exists, and does not have a heating means in a pressing portion that presses the side on which the bare chip does not exist. can do. This is a mode in which the above idea is advanced and the heating means provided in the pressing portion of the pressing means is provided only in the pressing portion that presses the side where the bare chip exists.

Further, as an embodiment, in the step of performing bare chip temporary fixing for each of the mounting regions, the underfill material has a viscosity of 1.0 × 10 ³ Pa · s to 1.0 × 10 ⁵ Pa · s. It can be carried out by heating. This viscosity is a viscosity before being completely cured, and is set as a viscosity that reliably maintains the (temporarily fixed) alignment state of the bare chip.

  Further, the step of applying the underfill material can be performed using a dispenser. It is common to use a dispenser. It is also possible to use a printing technique such as screen printing instead of the dispenser with the aim of improving efficiency.

  Here, the step of applying the underfill material may be performed by heating the underfill material with the dispenser. This lowers the initial viscosity of the underfill material by heating to make it easier to apply and improve the application efficiency.

  As an embodiment, the pressing means may include a heat-resistant resin plate material for pressing the wiring board. As a plate material for pressing the wiring board, one that is small in deformation due to heat is preferable. For example, a metal or a ceramic can be considered. In the case of a heat-resistant resin, although it is slightly flexible and hard, it is easy to follow the shape of the object to be pressed, which is considered preferable.

  Based on the above, embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an example of the configuration of a wiring board to which a method for manufacturing a flip package according to an embodiment of the present invention can be applied. This wiring board 10 is manufactured by applying the same product in multiple faces, and is in a state before being separated into individual pieces. Therefore, the area | region 10a for every singulation is taken along the length and breadth.

  In the region 10a for each separation, at least one mounting region where a bare chip is to be flip-mounted is prepared. In the mounting area, a land by a wiring pattern for flip mounting is formed. Although not shown, the area 10a may be provided with lands for mounting other components, interlayer connection conductors normally prepared as a wiring board, and the like. By flip-mounting the bare chip for the wiring board 10 before being singulated as described above, the efficiency of manufacturing the flip-mounted body is improved as described below.

  Next, FIG. 2 is a configuration diagram showing a partial cross-sectional view after applying the underfill material under the application of the flip package manufacturing method according to the embodiment of the present invention. In FIG. 2, the same components as those shown in FIG. As shown in FIG. 2, first, underfill material 21 is applied to a mounting region (a region where a land for mounting by wiring pattern 11 is provided) in which each bare chip is to be flip-mounted in each region 10a. The underfill material 21 is a paste-like material, for example, a resin such as an epoxy resin, a phenol resin, or an amine resin. A material in which conductive fine particles are dispersed in a resin to exhibit anisotropic conductivity can also be used.

  FIG. 3 is a process diagram showing perspectively an aspect of underfill material application, which is a step in the method of manufacturing a flip package according to an embodiment of the present invention. In FIG. 3, the same reference numerals are given to the same components as those already described in the drawings. As shown in FIG. 3, a dispenser can be used for applying the underfill material 21 onto the wiring substrate 10. That is, a predetermined amount of the underfill material 21 is applied to a predetermined position while moving the dispenser nozzle 31 for the wiring substrate 10 in which the regions 10a for each singulation are arranged vertically and horizontally.

  The viscosity of the underfill material 21 is normally 10 to 100 Pa · s at room temperature. In order to improve the efficiency of application from the dispenser nozzle 31, it is also useful to make the dispenser nozzle 31 heated to several tens of degrees Celsius so that the initial viscosity of the underfill material 21 is, for example, less than 10 Pa · s, thereby facilitating application. (Also refer to FIG. 7 described later). Moreover, it can replace with application | coating by dispenser and can also apply the underfill material 21 on the wiring board 10 using screen printing. It can be selected in consideration of efficiency.

  Next, FIG. 4 is a configuration diagram showing, in a partial cross section, a state after temporary fixing of the bare chip under the application of the method for manufacturing a flip package according to one embodiment of the present invention. In FIG. 4, the same components as those shown in the already described drawings are denoted by the same reference numerals. After the configuration shown in FIG. 2 is obtained by the application process of the underfill material 21 shown in FIG. 3, the process proceeds to obtain the configuration shown in FIG.

As shown in FIG. 4, this state is a state in which the bare chip 41 is temporarily fixed on the land by the wiring pattern 11 via the stud-like bumps 42. The underfill material 21A at this time is a semi-cured material of the underfill material 21 (for example, a viscosity of 1.0 × 10 ³ Pa · s to 1.0 × 10 ⁵ Pa · s), and is completely cured. It has not been.

  FIG. 5 is a process diagram showing in perspective a mode of bare chip temporary fixing, which is one step of the method for manufacturing a flip package according to one embodiment of the present invention. FIG. 6 is a view showing the relationship between the head of the flip chip bonder and the bare chip in the bare chip temporary fixing step shown in FIG. In FIG. 5 and FIG. 6, the same reference numerals are given to the same components as those already described in the drawings.

  As shown in FIG. 5, a flip chip bonder can be used for bare chip temporary fixing of the bare chip 41 onto the wiring substrate 10. That is, the bare chip is temporarily fixed by the flip chip bonder head 51 that sucks the bare chip 41 with the stud-like bumps 42 for the wiring substrate 10 on which the underfill material 21 is applied to each mounting region. Each time the bare chip temporary fixing is completed, a new bare chip 41 is attracted to the flip chip bonder head 51, aligned with a new mounting area, further pressed against the wiring substrate 10 side of the bare chip 41, and heated.

  The pressing of the bare chip 41 to the wiring board 10 side by the flip chip bonder head 51 can be set to a pressing force of, for example, 0.1 to 1 N in terms of one stud-like bump 42. The heating performed simultaneously with the pressing can be performed using a heater 51a (for example, a ceramic heater) provided in the flip chip bonder head 51 as shown in FIG. The heater 51a only needs to have a capability of semi-curing the underfill material 21 to temporarily fix the bare chip 41.

FIG. 7 is a graph showing an example of the temperature characteristics of the viscosity of the underfill material shown in FIGS. 2 and 3 (however, the temperature rising rate: 5 ° C./min), which is generally possessed by thermosetting resins. It is a graph for showing how much the viscosity is in a low viscosity state at normal temperature, a cured state at high temperature, and a semi-cured state exhibited at a temperature from a low viscosity state to a cured state. As shown in FIG. 7, the semi-cured state in the present application refers to a case where the viscosity is, for example, about 1.0 × 10 ³ Pa · s to 1.0 × 10 ⁵ Pa · s. This viscosity is a viscosity before being completely cured, and is set as a viscosity that can reliably maintain the temporarily fixed alignment state of the bare chip 41 until the next step.

  The characteristic graph shape shown in FIG. 7 generally changes so that the rising edge of the graph moves to the right as the temperature increase rate is increased. This is because, in general, thermosetting resins are cured by the amount of heat obtained by integrating the product of temperature and time. FIG. 7 shows the characteristics when the rate of temperature increase is 5 ° C./min. Actually, however, when the temperature rise rate is increased by increasing the heat generation temperature of the heater 51a, for example, about several tens of seconds. Among them, the underfill material 21 can be modified to a semi-cured underfill material 21A.

  By temporarily fixing the bare chip 41 so as to be kept in a semi-cured state like the underfill material 21A, the time required can be greatly reduced as compared with the case where each is completely cured and flip-mounted. In addition, the temporarily fixed state is reliably maintained until the next process, and there is no fear that the underfill material 21A is deformed and the mounting position of the bare chip 41 is shifted to reduce the reliability.

  Next, FIG. 8 is a process diagram showing in perspective a mode of underfill material curing transition, which is one step in the method of manufacturing a flip package according to one embodiment of the present invention. FIG. 9 is an explanatory diagram showing, in partial cross section, the process of underfill material curing transition shown in FIG. 8 and 9, the same reference numerals are given to the same components as those shown in the already described drawings.

  As shown in FIG. 8, the wiring board 10 for which the bare chip temporary fixing has been completed for all the mounting regions is collectively pressed from above and below by plate-like pressing portions 61 and 62 serving as pressing means, and is simultaneously heated. As shown in FIG. 9, this heating can be performed using heaters 61 a and 62 a (for example, ceramic heaters) provided inside the pressing portions 61 and 62. The plate-like pressing portions 61 and 62 are large in both area and volume as compared with the flip chip bonder head 51, and can sufficiently generate necessary heat.

  By this heating, the semi-cured underfill material 21A is changed to a cured underfill material 21B. At the time of pressing, for example, the temperature of the pressing portions 61a and 62a is raised in advance (for example, 180 to 250 ° C.), and this is performed with a pressing force of, for example, 0.1 to 1 N in terms of one stud-like bump 42. For example, in the case of mounting 16 bare chips on the wiring substrate 10 with 60 bumps / chip, if the pressure is 1N per bump, the pressing force is 960N.

  The pressing time varies depending on the properties of the underfill material 21 to be used, but can generally be about 5 to 90 seconds. It is more preferable in terms of heat transfer efficiency that the heating by the pressing parts 61 and 62 is larger in the heat generation capacity in the pressing part 62 on the bare chip 41 side than in the pressing part 61 on the wiring board 10 side. This is because heat transfer to the underfill material 21 </ b> A in the pressed state is greater due to the difference in thermal conductivity through the bare chip 41 (silicon) than through the wiring substrate 10 (resin). In heating from the pressing portion 61 on the wiring board 10 side, the temperature of the wiring board 10 (resin) is prevented from reaching the glass transition point. From these points, it can be considered that the lower pressing portion 61 is not provided with the heater 61a.

  For the plate-like pressing portions 61 and 62, for example, a heat-resistant resin plate material can be used. Basically, it is preferable that the plate material for pressing the wiring board 10 is small in deformation due to heat. In this respect, for example, metal or ceramic may be considered. In the case of a heat-resistant resin, although it is slightly flexible and hard, it is easy to follow the shape of the object to be pressed (the wiring board 10 on which the bare chip 41 is temporarily fixed), which is considered to be more preferable.

  FIG. 10 is a table showing the flip mounting time when the method for manufacturing a flip mounted body according to one embodiment of the present invention is applied in contrast to that in the comparative example. As shown in FIG. 10, when flip-chip bonders are used to flip-mount bare chips one by one (the left column in the table), the total mounting time increases in proportion to the number of bare chips. It takes a total of 616 seconds (77 seconds / 1 piece). On the other hand, in the case of the method described above (the right column in the table), 20 seconds / 1 piece is required for temporary fixing of the bare chip and 60 seconds are required for the final batch curing, so that the total time is 220 seconds. Therefore, a significant improvement in production efficiency can be achieved. This effect is further increased as the number of bare chips increases.

  Next, an example (an example of a component built-in wiring board) of the application of the flip mounted body obtained as described above will be described with reference to FIGS. FIG. 11 is a cross-sectional view showing a configuration of a component built-in wiring board using as a member a flip mount obtained by applying the flip mount manufacturing method described above. FIG. 12 is a process diagram showing a final lamination process for manufacturing the component built-in wiring board shown in FIG. In FIG. 11 and FIG. 12, the same reference numerals are given to the same components as those shown in the already described drawings.

  The component built-in wiring board shown in FIG. 11 includes insulating layers 101, 102, 103, 104, and 105, wiring layers (wiring patterns) 201, 11, 203, 204, 205, and 206, and an interlayer connector (by conductive composition printing). Conductive bumps) 301, 302, 304, 305, through-hole conductor 303, bare chip 41, stud-like bump 42, underfill material 21B, and solder resists 601 and 602.

  In FIG. 12, which is the final lamination step for obtaining the component built-in wiring board shown in FIG. 11, metal foils 201A and 206A are metal foils (copper foils) to be processed into the wiring layers 201 and 206, respectively. The prepregs 102A and 104A are precursors (semi-cured members) to be cured on the insulating layers 102 and 104, respectively. The respective wiring board materials 1, 2, and 3 are stacked and arranged in the arrangement as shown in FIG. Thereby, the prepregs 102A and 104A are completely cured, and the whole is laminated and integrated. At this time, due to the fluidity of the prepregs 102A and 104A generated by heating, the prepregs 102A and 104A are deformed and entered into the space around the bare chip 41 and the space inside the through-hole conductor 303.

  That is, as shown in FIG. 12, the component built-in wiring board shown in FIG. 11 uses a flip mounting body (wiring board material 1) as a member in production. The flip mounted body is laminated and integrated with the upper wiring board material 3 via the intermediate wiring board material 2 provided with the component opening 701 corresponding to the bare chip 41. In this lamination and integration, if the height of the bare chip 41 is not uniform, it may be used in the height direction or a gap may be easily formed, resulting in a decrease in yield. In this respect, if the flip mounting body according to the manufacturing method described above is used, since the collective pressing as shown in FIG. 8 is performed, the height of the bare chip 41 is made more uniform. Therefore, the effect of improving the yield can be obtained.

  1, 2, 3 ... wiring board material, 10 ... wiring board, 10a ... area for each piece, 11 ... wiring pattern, 21 ... underfill material (paste), 21A ... underfill material (semi-cured), 21B ... Underfill material (after curing), 31 ... Dispenser nozzle, 41 ... Bare chip, 42 ... Stud bump, 51 ... Flip chip bonder head, 51a ... Heater, 61, 62 ... Pressing part (pressing means), 61a, 62a ... Heater (heating means), 101, 102, 103, 104, 105 ... insulating layer, 102A, 104A ... prepreg, 201, 203, 204, 205, 206 ... wiring layer (wiring pattern), 201A, 206A ... metal foil (copper) Foil), 301, 302, 304, 305 ... interlayer connection (conductive bumps printed by conductive composition), 303 ... through hole Conductor, 601, 602 ... solder resist, 701 ... component opening.

Claims (8)

Applying a paste-like underfill material to each of the mounting regions of the wiring board in which a plurality of mounting regions in which the bare chip is to be flip-mounted are prepared;
A step of performing bare chip temporary fixing for each of the mounting regions in which the bare chip is aligned and pressed on the wiring substrate via the underfill material and heated to semi-harden the underfill material;
The wiring board is pressed from above and below by pressing means so that a plurality of bare chips on the wiring board are collectively pressed against the wiring board, and the underfill material is cured from a semi-cured state by heating. And a step of shifting to a state. A method for manufacturing a flip package.   The pressing means has a first heating means at a pressing portion that presses the side where the bare chip exists, and has a second heating means at a pressing portion that presses the side where the bare chip does not exist, 2. The method of manufacturing a flip package according to claim 1, wherein the heating means has a larger heat generation capacity than the second heating means.   The press means has a heating means in a pressing portion that presses the side on which the bare chip exists, and does not have a heating means in a pressing portion that presses the side on which the bare chip does not exist. The manufacturing method of the flip mounting body as described. The step of performing bare chip temporary fixing for each of the mounting regions is performed by heating so that the underfill material has a viscosity of 1.0 × 10 ³ Pa · s to 1.0 × 10 ⁵ Pa · s. The method for manufacturing a flip package according to claim 1 or 2, wherein   2. The method of manufacturing a flip package according to claim 1, wherein the step of applying the underfill material is performed using a dispenser.   6. The method of manufacturing a flip package according to claim 5, wherein the step of applying the underfill material is performed by heating the underfill material with the dispenser.   2. The method of manufacturing a flip mount assembly according to claim 1, wherein the pressing means includes a heat-resistant resin plate material for pressing the wiring board.   The method for manufacturing a flip package according to claim 1, wherein the paste-like underfill material includes an epoxy resin.

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