JP2000188367A - Manufacture of semiconductor package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor package, capable of reducing deformations such as warp produced when a flexible circuit board is applied to an opening part of a metal frame and maintaining that effect. SOLUTION: In a method for manufacturing a semiconductor package for carrying out mounting, wire-bonding, and resin sealing, etc., of a semiconductor element by the use of a structure, wherein a sheet-like flexible circuit board 7 is bonded to the opening part of a metal frame 1 with a bonding agent as an intermediate product for the semiconductor package, after the flexible circuit board 7 is bonded to the metal frame 1, warpage of the flexible circuit board 7 is reduced by reducing the water content within the flexible circuit board 7, and then the intermediate product obtained for the semiconductor package is vacuum-packed and sent to a next process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor package including a step of attaching a sheet-like flexible circuit board to an opening of a metal frame with an adhesive, and in particular, to reducing deformation such as warpage of the flexible circuit board. The present invention relates to a method for manufacturing a semiconductor package as described above.

[0002]

2. Description of the Related Art A conventional manufacturing apparatus for manufacturing a QFP (Quad Flat Package) uses a FBGA (Fine Pitch Ball Grid A).
There is a demand for a method of manufacturing a semiconductor package capable of manufacturing a CSP (Chip Scale Package) called rray).

As a part of this, conventionally, a single frame of a single circuit board having a circuit pattern on one side or both sides or a plurality of these single circuit boards are grouped together as a unit in a metal frame as a carrier frame. The fixed circuit board sheet is fixed, and the semiconductor element is mounted thereon,
JP-A-8-83866 and JP-A-9-2756 disclose methods of manufacturing a semiconductor package in which one surface is sealed with a resin.
No. 3, JP-A-9-22963.

Japanese Patent Application Laid-Open No. H08-83866 discloses a metal frame provided with an opening formed of a rectangular through hole, and a single piece of a circuit having a circuit pattern on one side or both sides provided in the opening. A circuit board, which is positioned and supported by mechanical support means, is used as an intermediate product for a semiconductor package, and is transported to each process, so that existing equipment can be used as is to mount semiconductor elements and wire. This is a method for manufacturing a semiconductor package that efficiently performs processes such as bonding and resin sealing. As the support means for positioning and supporting the circuit board on the metal frame, for example, a locking piece formed by cutting and erecting a plate material of the metal frame is used. The circuit board (single BGA product) can be easily removed from the metal frame.

A first advantage of using the above-mentioned intermediate product for a semiconductor package is that a waste portion of a printed circuit board when a conventional strip-shaped printed circuit board is used can be eliminated. That is, in a conventional manufacturing method, a large-sized printed circuit board provided with a predetermined wiring pattern is cut into strips, and the printed board formed in the strip shape is transported to each process to produce a product. However, the use of a single circuit board and supporting it on a metal frame does not cause such waste. A second advantage resides in that processes such as mounting of a semiconductor element, wire bonding, and resin sealing can be efficiently performed using existing facilities as they are.

Japanese Patent Application Laid-Open Nos. 9-27663 and 9-22963 disclose a plurality of single circuit boards in place of the individual single circuit boards described above. The integrated circuit board sheet which is connected and integrated as one unit is handled.

[0007] Typically, FIG.
1 shows an intermediate product (semiconductor circuit element mounting substrate frame) for a semiconductor package disclosed in Japanese Unexamined Patent Publication (Kokai) Publication. The semiconductor circuit element mounting board frame 30 includes a single semiconductor circuit board 32 and a single metal board layer 31 which are connected to side rails 35 by connection tabs 36 and are sequentially linearly arranged. The semiconductor circuit element mounting board 33 is provided via a prepreg layer which is a heat conductive adhesive layer, and as a result, the semiconductor circuit element mounting board 33 is connected in a sheet shape. Reference numeral 34 is a positioning reference hole provided in the side rail 35.

According to the intermediate product for a semiconductor package which handles the collective circuit board sheet, a drawback in handling a single circuit board of individual pieces, that is, handling such as transport and positioning of individual circuit boards becomes complicated. It is possible to solve the problem that the quality and the work efficiency of mounting the semiconductor circuit element are reduced due to displacement or damage, and the productivity is significantly impaired.

[0009]

However, in the above-mentioned prior art, there has been no study on a method of attaching the flexible circuit board to the metal frame with an adhesive, and the flexible circuit board generated at the time of the attachment has not been studied. A method for reducing deformation such as warpage has not been established.

On the other hand, the present applicant has developed the following method for manufacturing a semiconductor package. That is, as shown in FIG. 4, an opening 2 is provided in a metal frame 1, and a sheet-like flexible circuit board 7 is adhered to the opening with an adhesive as shown in FIG. This is a method for carrying out processing such as mounting of the semiconductor element 9, wire bonding, resin sealing, and the like by transporting the same to each step.

According to this manufacturing method, for example, it is only necessary to apply an adhesive to two, three, or four sides of the frame opening in the frame width direction and attach the flexible circuit board 7 with the adhesive. Since connecting tabs and the like are unnecessary, the production of the metal frame 1 and the flexible circuit board 7
Is very easy to handle, and the manufacturing time can be reduced. In addition, the area occupied by the flexible circuit board 7 on the metal frame 1 is small, and an increase in productivity can be realized. That is, as in the conventional case where the individual circuit boards are handled and supported on the metal frame, there is an advantage that the material of the circuit boards is not wasted. Also,
There is also an advantage that processing such as mounting of the semiconductor element 9, wire bonding, and resin sealing can be performed efficiently using existing facilities as they are.

However, in this manufacturing method, the space immediately below the flexible circuit board 7 is the space of the opening 2, and there is no support by the metal substrate layer 31 as shown in FIG.
Since only two sides, three sides or four sides of the flexible circuit board 7 are fixed with an adhesive, the flexible circuit board 7 is warped as shown in FIG. There's a problem.

When deformation such as warpage occurs in the flexible circuit board, the flatness of the mounting portion of the semiconductor element 9 and the wire bond connection portion on the flexible circuit board deteriorates, and this becomes a major obstacle in mounting the semiconductor and in wire bonding. there is a possibility. In addition, the semiconductor chip 9 is damaged after mounting the chip of the semiconductor element 9, for example, during molding, and cannot be used in the worst case.

Accordingly, an object of the present invention is to solve the above-mentioned problems, to reduce deformation such as warpage when a flexible circuit board is attached to an opening of a metal frame, and to maintain the effect thereof. A method of manufacturing a package is provided.

[0015]

Means for Solving the Problems In order to achieve the above object, the present invention is configured as follows.

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor package including a step of attaching a sheet-like flexible circuit board to an opening of a metal frame with an adhesive, wherein the flexible circuit board is attached to the metal frame. Later, by reducing the moisture in the flexible circuit board, to reduce the warpage of the flexible circuit board,
The flexible circuit board is vacuum-packed and sent to the next step.

According to a second aspect of the present invention, a sheet-like flexible circuit board bonded to an opening of a metal frame with an adhesive is used as an intermediate product for a semiconductor package, and is conveyed to each process. Thus, in the method of manufacturing a semiconductor package for performing processing such as mounting of a semiconductor element, wire bonding, and resin sealing, after attaching the flexible circuit board to the metal frame, reducing moisture in the flexible circuit board Thus, the warpage of the flexible circuit board is reduced, and the obtained intermediate product for a semiconductor package is vacuum-packed and sent to the next step.

Specifically, as schematically shown in FIG. 1, after a sheet-like flexible circuit board is attached to the opening of the metal frame with an adhesive (step (a)), the flexible circuit board is For example, by heating or leaving in a low-humidity environment (for example, in an atmosphere having a relative humidity of 30%) for a certain period of time, the moisture in the flexible circuit board is reduced, thereby reducing the warpage of the flexible circuit board (step ( b)). Next, the obtained intermediate product for a semiconductor package is vacuum-packed (step (c)) and transported to each step in a state where the invasion of humidity is prevented (step (d)). A process such as resin sealing is performed (step (e)).

In the case of a flexible circuit board, the form of a single flexible single circuit board having a circuit pattern on one side or both sides, and a flexible circuit formed by combining a plurality of these single circuit boards into one sheet unit Both forms of an integrated circuit board are included.

As a means for reducing the moisture in the flexible circuit board, a method of heating the flexible circuit board is effective because the effect of reducing the moisture is great. But,
The same effect can be obtained by leaving the flexible circuit board in a low humidity environment (for example, in an atmosphere with a relative humidity of 30%) for a certain period of time. Prior to attaching the sheet-like flexible circuit board to the opening of the metal frame with an adhesive, the flexible circuit board is placed in a high humidity atmosphere (for example, at a temperature of 65 ° C.).
(In a high-temperature and high-humidity bath at 85 ° C. and a relative humidity of 85%) for a certain period of time or more, the flexible circuit board may be humidified in advance.

In the method for manufacturing a semiconductor package according to the first, second, or third aspect, it is preferable that a hygroscopic agent such as silica gel is put into the vacuum pack together (claim 4). Further, in the method of manufacturing a semiconductor package according to claim 2 or 3, the semiconductor package intermediate product put in a vacuum pack is put in a shipping box,
A desiccant such as silica gel may be put in the shipping box (claim 5).

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment.

FIG. 3 shows a form of an intermediate product for a semiconductor package used in the method of manufacturing a semiconductor package according to the present invention. In the intermediate product for a semiconductor package, a rectangular opening 2 (see FIG. 4) is provided on a metal frame 1 as a carrier frame, and a circuit is formed on one or both sides of a polyimide resin insulating film with respect to the frame opening 2. A flexible circuit board 7 cut out from a patterned flexible tape (a so-called TAB tape) 4 (see FIG. 6) is attached with an adhesive 8 (see FIG. 5). The sticking of the flexible circuit board 7 is a portion of the peripheral area of the frame opening 2 on the metal frame along two sides in the frame width direction and overlapping the flexible circuit board after the sticking, An adhesive 8 (see FIG. 5) is applied to this portion, and the flexible circuit board 7 is attached to the frame opening 2 of the metal frame 1. This intermediate product for a semiconductor package is manufactured as follows.

First, as shown in FIG. 4, a 160 mm × 40 mm copper alloy having a thickness of 200 μm is etched into
A metal frame 1 is prepared by linearly forming and arranging four square holes of 0 mm × 30 mm. By forming the frame openings 2, the side rail regions 1 a and 1 a are left on the two sides (both sides) of the metal frame 1 in the frame width direction in common with the frame openings 2. The partitioned area 1b is left between the openings 2. A plurality of positioning guide holes 3 are formed in the side rail region 1a of the metal frame 1.

Next, as shown in FIG. 6, the flexible circuit board 7 is a coil-shaped 50 μm-thick flexible tape in which a circuit pattern is provided on one or both sides of a polyimide resin insulating film capable of high-density mounting. From a (so-called TAB tape) 4, a 30 mm × 34 mm rectangle is punched out with a die by a press working method using a die (not shown), and the obtained flexible tape cut portion is used as a flexible circuit board 7. The dimensions of the flexible circuit board 7 are the same as the length of the frame opening 2 and the width is 4
mm larger. The reason why the width of the flexible circuit board 7 is slightly longer than that of the frame opening 2 is to use the protruding portion of the short side of the flexible circuit board 7 as a portion 7b to be adhered to the above-mentioned bonding margin. In addition, guide holes 5 for feed positioning are formed at a predetermined pitch on a side portion of the flexible tape 4.

In the case of this embodiment, the flexible circuit board 7 is formed by connecting four single circuit boards 6, which are the wiring pattern portions of the flexible tape 4, in such a manner that a frame in the shape of a cross remains as a connecting portion 7a. Consisting of However, the flexible circuit board 7 can have any desired shape in which the required number of the single circuit boards 6 are connected.

Next, as shown in FIG.
The adhesive 8 is applied to a portion of the paste margin. That is, using a mechanically controlled dispenser, the thermosetting adhesive 8 is linearly applied to the positions along the two sides in the frame width direction at the peripheral edge of each hole which is the peripheral area of the frame opening 2. Apply. The length of the portion where the flexible circuit board 7 overlaps the metal frame 1 is 30 mm, and the adhesive 8 is applied slightly shorter than that, that is, a 28 mm length is applied inside the portion, and the metal frame 1 and the flexible circuit are applied. The adhesive 8 was prevented from leaking to portions other than the portion where the substrate 7 overlaps. The curing temperature of the adhesive 8 used here is 250 ° C. Therefore, using a reflow furnace, 100 ° C., 30 seconds + 150 ° C.,
Incomplete curing is performed by heating for 30 seconds.

Thereafter, the flexible tape 4 shown in FIG.
The above-mentioned bonded portion 7b of the flexible circuit board 7 obtained by punching the above into a rectangle of 30 mm × 34 mm with a metal mold is superimposed on the adhesive application portion of the metal frame 1, and 6 kg using a bonding mold heated to 270 ° C. Then, the flexible circuit board 7 and the metal frame 1 are bonded together by applying a pressure of 1 / cm 2 for 1 second.

These steps are repeated for one metal frame 1.

In the attaching step, there is no support material in the space directly below the flexible circuit board 7;
Since only two sides around the flexible circuit board 7 are fixed with an adhesive, the flexible circuit board 7 is likely to be warped as shown in FIG. When the flexible circuit board 7 is fixed to the metal frame 1 as shown in FIG. 3, if the flexible circuit board 7 where the semiconductor element 3 is mounted is warped as shown in FIG. 8, the semiconductor element 3 is damaged during molding. give.

Therefore, as shown in FIG. 3, after the flexible circuit board 7 is attached to the metal frame 1,
After the step (a) in FIG. 1, the flexible circuit board 7 is heated to reduce the moisture inside the flexible circuit board 7 (step (b) in FIG. 1), thereby reducing the warpage of the flexible circuit board 7. In short, when the flexible circuit board 7 is attached to the metal frame 1 and then heated, the internal moisture is reduced and shrinks, so that the amount of warpage of the flexible circuit board 7 is reduced.

Thus, an intermediate product for a semiconductor package was completed.

However, if the intermediate product for a semiconductor package is managed so as to be transported to the next step in this state, the moisture inside the flexible circuit board 7 may return to its original state over time. In particular, when the flexible circuit board 7 is left in a high-humidity state during transport,
Absorb moisture and cause deformation.

Then, the obtained intermediate product 20 for a semiconductor package was placed in a vacuum pack 21 as shown in FIG. 2, and a vacuum was applied to heat and seal the opening 23 of the pack, thereby preventing the invasion of humidity. Further, inside the vacuum pack 21, silica gel 22 was enclosed as a hygroscopic agent and kept in a low humidity atmosphere (step (c) in FIG. 1).

In this embodiment, the intermediate product 20 for a semiconductor package is placed in the vacuum pack 21 and the silica gel 22 is enclosed at the same time. However, the silica gel 22 does not have to be placed. Alternatively, the vacuum pack 21 in which the semiconductor package intermediate product 20 is simply placed may be placed in a shipping box, and the silica gel 22 may be placed in the shipping box.

Next, in order to manufacture the small grid area array type semiconductor package shown in FIG. 7, the semiconductor package intermediate product 20 obtained as described above was placed in a vacuum pack 21 as shown in FIG. In this state, the wafer was transported to each step (step (d) in FIG. 1), and processing such as mounting of a semiconductor element, wire bonding, and resin sealing was performed (step (e) in FIG. 1).

In FIG. 7, the flexible circuit board 60 is one of four flexible circuit boards formed as a single circuit board 6 (FIGS. 3 and 6) in the shape of a "T" in a continuous manner. The copper foil 13 on one side forms a circuit pattern.

First, in a state where the flexible circuit board 7 is stuck to the metal frame 1, a resist resin 14 is applied to the surface of the circuit pattern on the conductive circuit board 6,
The semiconductor element 9 is mounted.

Next, the wire 9 is bonded by wire bonding between the electrode 9a of the semiconductor element 9 and the connection pad (gold plating 12b) of the circuit pattern.

Further, a mold resin 10 or a potting material is applied on the semiconductor element 9 and the bonding wires 11. At this time, the portion of the adhesive 8 described above functions as a weir that prevents the resin from flowing out of the region of the opening 2 on two sides in the width direction. In FIG. 3, reference numeral 16 denotes a mold line.

After resin sealing, solder balls 1 are provided on the lower surface of circuit board 60 as external connection terminals for connection to a mounting board or the like.
5 is attached. A part of the circuit pattern is led out to one side on the other side through a via hole provided with gold plating 12a that penetrates the circuit board 60, and the lead portion is connected to the solder ball 15. In the case of the BGA, solder balls are used as external connection terminals. However, lead pins and the like can be used as external connection terminals in addition to the solder balls as a single-sided resin-sealed semiconductor package.

Finally, by removing the flexible circuit board 7 from the metal frame 1 or the circuit board 60 from the flexible circuit board 7, a small grid area array type semiconductor package can be obtained as a single BGA product.

Normally, flexible tapes for small-sized grid area array type semiconductor packages as described above cannot be produced using an apparatus for manufacturing a lead frame package, and investment such as introduction of a new apparatus is required. Required. However, if the intermediate product for a semiconductor package according to the present embodiment is used, it is possible to manufacture a semiconductor package by using a device for a large lead frame package. That is, according to the method of manufacturing a semiconductor package according to the above-described embodiment, a conventional apparatus for manufacturing a QFP is called a FBGA (Fine Pitch Ball Grid Array).
The SP can be manufactured. Further, the present invention has no limitation on the semiconductor element to be processed, and can be applied to any of memories such as DRAM and SRAM, and logic systems such as CPU and MPU.

In the above embodiment, the flexible circuit board was heated as a method of reducing the moisture in the flexible circuit board. However, the flexible circuit board may be placed in a low humidity environment for a certain period of time or more, for example, left in an atmosphere of a relative humidity of 30% for 12 hours.

In addition, prior to attaching the sheet-like flexible circuit board to the opening of the metal frame with an adhesive, the flexible circuit board is placed in a high-humidity atmosphere for a certain period of time and humidified in advance. You may leave. For example, before attaching the flexible circuit board 7 to the metal frame 2, the flexible circuit board 7 is placed in a high-temperature and high-humidity bath at a temperature of 65 ° C. and 85% RH (relative humidity) for 12 hours or more, so that the flexible circuit board 7 Put in. In other words, the flexible circuit board 7 is humidified and sufficiently stretched by absorbing moisture. This humidification process, in order to increase the efficiency, the stage of FIG.
That is, the process is performed in a state where the flexible circuit board 7 is wound around a metal reel in the form of a flexible tape (TAB tape) 4. Thereafter, the flexible circuit board 7 punched by a mold is attached to the metal frame 1 (step (a) in FIG. 1). Then, the flexible circuit board 7 is left in an atmosphere having a relative humidity of 30% for 12 hours or more to reduce and shrink the internal moisture, thereby reducing the warpage of the flexible circuit board 7 (step (b) in FIG. 1). ).

[0046]

As described above, the present invention relates to a method of manufacturing a semiconductor package including a step of attaching a sheet-like flexible circuit board to an opening of a metal frame with an adhesive, or to a method of manufacturing a semiconductor package. A sheet-like flexible circuit board attached with an adhesive is used as an intermediate product for a semiconductor package, and is conveyed to each process to perform processing such as mounting of a semiconductor element, wire bonding, and resin sealing. In the method of manufacturing a semiconductor package, after attaching the flexible circuit board to the metal frame, the moisture in the flexible circuit board is reduced to reduce the warpage of the flexible circuit board, and the resulting semiconductor package intermediate The product is vacuum-packed and sent to the next process.

When the vacuum packing is not performed, even if the moisture in the flexible circuit board is reduced after sticking, the flexible circuit board absorbs the moisture again and returns (extends).
Therefore, the effect of reducing the warpage of the substrate is lost, but in the present invention, the obtained intermediate product for a semiconductor package is vacuum-packed and subjected to moisture-proof packing, so that the flexible circuit board does not absorb moisture and the flexible circuit board does not absorb moisture. The circuit board can be maintained without warpage.

Therefore, it is possible to reduce damage to the semiconductor element after mounting the semiconductor element, for example, during molding. Therefore, according to the present invention, a method for manufacturing a semiconductor package having a high yield can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating an example of a method for manufacturing a semiconductor package according to the present invention.

FIG. 2 is a diagram showing a state in which an intermediate product for a semiconductor package obtained during the manufacturing method of the present invention is vacuum-packed.

FIG. 3 is a plan view showing an intermediate product for a semiconductor package obtained during the manufacturing method of the present invention.

FIG. 4 is a plan view showing a metal frame used in the manufacturing method of the present invention.

FIG. 5 is a view showing an opening of a metal frame used in the manufacturing method of the present invention.

FIG. 6 is a view showing a flexible tape used for producing a flexible circuit board used in the manufacturing method of the present invention.

FIG. 7 is a sectional view showing an example of a semiconductor package manufactured by the manufacturing method of the present invention.

FIG. 8 is a cross-sectional view showing the warpage of the flexible circuit board in the embodiment of the method of manufacturing a semiconductor package according to the present invention.

FIG. 9 is a view showing a conventional intermediate product for a semiconductor package.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Metal frame 2 Opening 4 Flexible tape 6 Single circuit board (Wiring pattern part of flexible tape) 7 Flexible circuit board (Cutting part of flexible tape) 8 Adhesive 9 Semiconductor element 10 Mold resin 20 Intermediate product for semiconductor package 21 Vacuum Pack 22 silica gel

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hironori Shimazaki 3550 Kida Yomachi, Tsuchiura-shi, Ibaraki Hitachi Cable, Ltd. System Materials Research Laboratory F-term (reference) 5F044 KK03 MM08 MM48 5F067 BA01 BE10 CC02 CC08

Claims (5)

[Claims] 1. A method of manufacturing a semiconductor package, comprising: attaching a sheet-like flexible circuit board to an opening of a metal frame with an adhesive, after attaching the flexible circuit board to the metal frame. A method for manufacturing a semiconductor package, comprising: reducing warpage of a flexible circuit board by reducing moisture in the board; and vacuum-packing the flexible circuit board and sending it to the next step. 2. An intermediate product for a semiconductor package in which a sheet-like flexible circuit board is adhered to an opening of a metal frame with an adhesive, and is conveyed to each step to mount a semiconductor element. In a method of manufacturing a semiconductor package for performing a process such as wire bonding or resin sealing, after attaching the flexible circuit board to the metal frame, the warpage of the flexible circuit board is reduced by reducing moisture in the flexible circuit board. A semiconductor package manufacturing method characterized in that the intermediate product for a semiconductor package obtained is vacuum-packed and sent to the next step. 3. The method of manufacturing a semiconductor package according to claim 1, wherein the flexible circuit board is heated to reduce moisture in the flexible circuit board. 4. A method for manufacturing a semiconductor package according to claim 1, wherein a moisture absorbent is put in the vacuum pack. 5. The method for manufacturing a semiconductor package according to claim 2, wherein the intermediate product for a semiconductor package is placed in a vacuum pack, placed in a shipping box, and a desiccant is placed in the shipping box. A method of manufacturing a semiconductor package, comprising: