JPH08153946A - Plastic molded circuit board and its manufacture - Google Patents

Abstract

PURPOSE: To eliminate influence of external force and improve reliability, by arranging semiconductor elements and wiring patterns in recessed parts formed at positions deviated from the center, and installing bonding posts of a circuit board where the semiconductor elements are connected with the wiring patterns by using gold wires and are sealed with resin, along the outside of the recessed parts at the longest distance from the board center. CONSTITUTION: When a semiconductor element 5 is mounted on a wiring board 1, the semiconductor element 5 is dropped in a recessed part 6 and arranged, and the electric connection between the semiconductor element 5 and a wiring pattern 3 is formed by using gold wires 18. The wiring board 1 is sandwiched from the upper and the lower directions by metal molds, mold resin is injected, and molding and sealing are performed. When an external force is applied, the stress becomes maximum at the center O. In this case, the semiconductor element 5 leaves the center, and further bonding posts 3a of the wiring pattern 3 which are formed so as to surround the recessed part 6 are arranged at the position adjacent to the sides of the recessed part 6, i.e., the position which is hardly affected by bending stress, so that the damage to the gold wires 18 can be prevented.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an IC (Integrated Circuit).
The present invention relates to a resin-sealed circuit board used by being embedded in a card and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art As the card-based society advances, the magnetic cards that have been used up to now have problems such as lack of memory for safety or new service demand. Therefore, in order to meet the demands of the times, there is a tendency to use IC cards instead of magnetic cards. This IC card is a plastic card in which a microprocessor and an IC memory are embedded. Semiconductor elements such as the microprocessor and the IC memory are mounted on a wiring board, and the semiconductor element is mounted on the wiring board with a resin. It is incorporated as a so-called COB (Chip on Bord) type circuit board sealed with a material.

5 and 6 show an example of a conventional IC card COB module, that is, a resin-sealed circuit board. FIG. 5 is a plan view of the circuit board in a state before resin-sealing, FIG. 6 is a vertical sectional side view of the circuit board shown in a resin-sealed state. 5 and 6, in this circuit board, the external connection terminals 52 are formed on the back surface side of the wiring board 51 and the wiring pattern 53 is formed on the front surface side, and the external connection terminals 52 and the wiring pattern 53 are formed. Are electrically connected to each other by a through hole 54. Further, a recess 56 for dropping and arranging the semiconductor element 55 is formed in a substantially central portion of the wiring board 51. In addition, on the front surface side of the wiring board 51, a solder resist 57 made of epoxy resin is formed on the wiring pattern 53 so as to surround the recess 56.

Then, the semiconductor element 5 is formed on the wiring board 51.
When mounting 5, the semiconductor element 55 is first placed in the recess 56 in a state of being dropped. Next, a gold wire 68 is used to establish an electrical connection between a lead (not shown) of the semiconductor element 55 and the bonding post 53a of the wiring pattern 53, and then a molding resin 58 is injected into the inside surrounded by the solder resist 57. Transfer molding is performed by using the mold resin 58 (see FIG. 6) to form a resin-sealed circuit board. FIG. 6 is a vertical cross-sectional side view showing the state after the semiconductor element 55 is thus resin-sealed.

FIG. 7 and FIG. 8 show another example of a conventional IC card COB module, that is, a resin-sealed circuit board. FIG. 7 shows a resin-sealed type before being resin-sealed. FIG. 8 is a plan view of the circuit board, and FIG. 8 is a vertical sectional side view of the resin-sealed circuit board shown in a resin-sealed state. 7 and 8
In FIG. 5, the same reference numerals as those in FIGS. 5 and 6 indicate the same parts as those in FIGS. 7 and 8, this resin-sealed circuit board also has an external connection terminal 52 formed on the back surface side of the wiring board 51 and a wiring pattern 53 formed on the front surface side, and the external connection terminal 5 is also provided.
2 and the wiring pattern 53 are electrically connected by a through hole 54. Further, a recess 56 for dropping and arranging the semiconductor element 55 is formed at a position shifted to one side from the center of the wiring board 51. In addition, on the front surface side of the wiring board 51, a solder resist 57 made of epoxy resin is formed on the wiring pattern 53 so as to surround the outer peripheral portion of the wiring board 51. When forming the solder resist 57,
A part of the solder resist 57 is poured into the through hole 54 to be closed.

The semiconductor element 5 is formed on the wiring board 51.
When mounting 5, the semiconductor element 55 is first placed in the recess 56 in a state of being dropped. Next, a gold wire 68 is used to establish an electrical connection between a lead (not shown) of the semiconductor element 55 and the bonding post 53a of the wiring pattern 53, and then a molding resin 58 is applied to an inner portion 60 surrounded by the solder resist 57. Is injected to perform transfer molding, and is sealed with this molding resin 58 (see FIG. 8) to form a resin-sealed circuit board. In addition, after molding, the groove 59 having a substantially V-shaped cross section is formed in an appropriate position in a state of extending in the vertical and horizontal directions from above the molding resin 58.
This groove 59 facilitates the flexure of the wiring board 51,
The flexure absorbs an external force applied to the semiconductor element 55. FIG. 8 is a vertical cross-sectional side view showing the state after the semiconductor element 55 is thus resin-sealed.

[0007]

Among the conventional resin-sealed circuit boards described above, the resin-sealed circuit boards shown in FIGS. 5 and 6 are resin-molded by transfer molding. In this case, the mold for transfer molding is sandwiched from the upper and lower surfaces of the wiring board 51, and the molding resin 58 is injected. However, in the resin-sealed circuit board of this structure, the wiring board 5
Since the wiring pattern 53 partially passes under the solder resist 57 with which the mold for transfer molding is brought into contact when sandwiching 1, the pattern thickness (usually, in the portion where the wiring pattern 53 passes) (usually About 30 microns) above the surroundings. Therefore, when the wiring substrate 51 is sandwiched by the upper and lower molds by transfer molding, a high part is in close contact with the mold, but a low part is not in close contact with the mold and a gap is formed. There was a problem that an outflow, that is, a flash occurred. Further, since the position on which the semiconductor element 55 is mounted is the center of the wiring board 51, there is a problem that an external force may adversely affect the semiconductor element 55.

On the other hand, in the resin-sealed circuit board shown in FIGS. 7 and 8, after molding, the groove 59 having a substantially V-shaped cross section is formed so as to extend vertically and horizontally from above the molding resin 58. However, the groove 59 makes it easier to obtain the flexure of the wiring board 51, and the flexure absorbs the external force applied to the semiconductor element 55. However, when the breaking strength test of this resin-sealed type circuit board was carried out, it was found that there was another problem. This will be described with reference to the schematic diagrams of the breaking strength test shown in FIGS. 9 and 10. In this breaking strength test, both end portions of the mold resin 58 are supported by two supporting points 70a, 70a, and the resin sealing is performed. A static circuit board is placed (see FIG. 9) and a load P is applied from the back surface side where the external connection terminals 52 are formed (see FIG. 10). In this test, in the portion where the semiconductor element 55 and the wiring board 55 are bonded to each other and at the end portion 71 thereof, breakage occurs (see FIG. 9) and peeling (see FIG. 10) and other inconveniences occur. This is because the stress is maximum at the centers of the support points 70a and 70a, and the semiconductor element 55 has a higher Young's modulus than the mold resin 58 and the wiring board 51, as shown in FIG. Therefore, it does not bend like the mold resin 58 and the wiring board 51. Therefore, there has been a problem that shearing forces F1 and F2 act on the end portion 71 to cause peeling and the effect of the groove 59 provided on the surface of the mold resin 58 does not appear.

The present invention has been made in view of the above problems, and an object thereof is to provide a resin-sealed circuit board which can improve reliability by eliminating the influence of external force and a method for manufacturing the same. .

[0010]

According to the present invention, there is provided a wiring board, a recess formed at a position deviated from the center of the wiring board, and the center of the wiring in the recess. A semiconductor element arranged displaced from the center of the substrate, and a wiring pattern formed on one surface side of the wiring board, while connecting a bonding post of the wiring pattern and the semiconductor element with a gold wire, In a resin-sealed circuit board obtained by sealing the surface of the wiring board with a mold resin, the bonding posts are provided outside the recess farthest from the center of the wiring board and along the recess. This is achieved by the following configuration.

[0011]

According to this structure, in the resin-sealed circuit board, when an external force is applied, the stress is maximized at the center O, and the resin O is destroyed there. Although it can be said that it is the weakest part, the semiconductor element in the present invention is provided in a recess formed at a position shifted from the center of the wiring board to one side in the horizontal direction (x axis) and the vertical direction (y axis). The post formed in the wiring pattern that is arranged so that the center where the semiconductor element is arranged is separated from the center of the wiring board and that surrounds the recess is
In a direction adjacent to the side of the recess on the side most displaced from the center O of the wiring board, that is, at a position farthest from the center O of the wiring board which is less susceptible to bending stress, the semiconductor element is directed in one direction. Even if the wiring board and the mold resin are broken, the amount of the breakage is small and the gold wire can be prevented from being broken.

Further, in the case where a wiring pattern is provided around the cavity of the transfer mold, and a solder resist is provided so as to cover the wiring pattern, the solder resist contacting the mold is made. The surface is smoothed, and it is securely held by the mold.

When a groove suitable for reducing Young's modulus is provided on the surface of the mold resin, and when the groove is formed such that the range of the recess extends to the position of the groove, bending and bending at the groove portion The breakage can be easily obtained, and the external force applied to the semiconductor element can be absorbed to reduce the influence on the semiconductor element and the like. Further, when the groove is provided so as to avoid the bonding post, it is possible to prevent the gold wire from breaking during bending and breaking.

[0014]

Embodiments of the present invention will be described in detail below with reference to the drawings. 1 and 2 show an IC according to the present invention.
FIG. 1 shows an example of a COB module for a card, that is, a resin-sealed circuit board. FIG. 1 is a plan view of the circuit board before being resin-sealed, and FIG. 2 is a circuit board shown in a resin-sealed state. It is a vertical side view.

1 and 2, in this circuit board,
The external connection terminals 2 are formed on the back surface side of the wiring board 1 and the wiring pattern 3 is formed on the front surface side, and the external connection terminals 2 and the wiring pattern 3 are electrically connected by through holes 4. Has been done. Further, a recess 6 for dropping and placing the semiconductor element 5 is formed at a position shifted from the center of the wiring board 1 to one side in the horizontal direction (x axis) and the vertical direction (y axis). There is. At this time, the post 3a formed in the wiring pattern 3 surrounding the recess 6 is located at a position adjacent to the side 6a of the recess 6 on the side displaced from the center O of the wiring board 1, that is, The center O of the wiring board 1 which is hardly affected by bending stress
The semiconductor element 5 is arranged in a direction away from the y-axis direction in one direction. Further, in this embodiment, the distance between the x1 portion (the end of the semiconductor element 5) and the x2 portion (the end of the wiring board 1) in the horizontal direction is 1.4 mm or less, and the distance of the y1 in the vertical direction is The distance between the portion (end of the semiconductor element 5) and the portion y2 (end of the wiring board 1) is shifted by 2.25 mm or less. Here, the distances of 1.4 mm and 2.25 mm are the minimum values that can be achieved at present, and the mounting position is x1.
Is defined by the portion of x1, the portion of x2, and the portion of y1 and the portion of y2, because the ratio of the semiconductor element 5 in the wiring board 1 becomes smaller, the center of the semiconductor element 5 is separated from the center of the wiring board. The purpose is to go.

In addition, a recess 6 is formed on the front surface side of the wiring board 1.
The wiring pattern 3 is formed so as to surround the outside of the wiring pattern 3, and the gate and runner 10 and the cavity other than the portion 12 that becomes the gate opening of the transfer mold molding die are formed so as to surround the outside of the wiring pattern 3. Area 11
A solder resist 7 made of an epoxy resin is formed in a portion corresponding to. When the solder resist 7 is formed, the solder resist 7 is formed on the wiring pattern 3 and the wiring pattern 3 is arranged below the solder resist 7 to eliminate the unevenness in this portion. In order to prevent the flash from being generated when the molding resin 8 is injected, it is easy to adhere to the mold during transfer molding.

When the semiconductor element 5 is mounted on the wiring board 1, the semiconductor element 5 is first placed in the recess 6 in a state of being dropped. Next, an electrical connection is made between the semiconductor element 5 and the wiring pattern 3 with a gold wire 18, and then the wiring board 1 is sandwiched by transfer mold forming dies from above and below, and is placed inside the solder resist 7. The molding resin 8 is injected to perform transfer molding, and the molding resin 8 (see FIG. 2) is used for sealing. Then, the resin-sealed circuit board is formed. Figure 2
FIG. 4 is a vertical cross-sectional side view showing a state after the semiconductor element 5 is thus resin-sealed.

Therefore, in the resin-sealed circuit board formed in this way, when an external force is applied, the stress becomes maximum at the center O and is destroyed there.
It can be said that the center O is the weakest portion against the external force, but the semiconductor element 5 in the present embodiment has the center O of the wiring board 1.
The center of the wiring board 1 is located in the recess 6 formed at positions shifted from the horizontal direction (x-axis) and the vertical direction (y-axis) to one side, and the semiconductor element 5 is located in the recess 6. And the bonding post 3a formed on the wiring pattern 3 provided so as to surround the recess 6
Is a position adjacent to the side 6a of the recess 6 on the side displaced from the center O of the wiring board 1, that is, in the vertical direction (y-axis direction) from the center O of the wiring board 1 which is less susceptible to bending stress. Since the semiconductor element 5 is arranged at the farthest position in one direction, even if the space between the wiring board 1 and the mold resin 8 is broken, the amount of the breakage is small and the gold wire 18 It is possible to prevent disconnection. In addition,
In the case where the bonding post (3a) and the gold wire (18) shown by dotted lines in FIG. 1 are provided in a state close to the center of the wiring board 1, the wiring board 1 and the molding resin 8 can be properly bent and destroyed. You will have to avoid it, so you must avoid it.

When the solder resist 7 made of epoxy resin is formed on the portion corresponding to the periphery 11 of the cavity, the solder resist 7 is formed on the wiring pattern 3, and the wiring pattern 3 is formed on the lower side of the solder resist 7. Since the unevenness is eliminated in this part by arranging, the adhesiveness with the mold at the time of transfer molding is improved, and flash other than the air vent is eliminated. Further, since the gate port 10 is not patterned, the mold resin is likely to enter, and unfilling is unlikely to occur.

FIGS. 3 and 4 show another embodiment of the IC card COB module according to the present invention, that is, a resin-sealed circuit board. FIG. 3 shows the circuit board before resin-sealed. FIG. 4 is a vertical side view of the circuit board shown in a resin-sealed state. 3 and 4, the same reference numerals as those in FIGS. 3 and 4 denote the same parts as those in FIGS. 3 and 4. 3 and 4, this circuit board also has the external connection terminals 2 formed on the back surface side of the wiring board 1 and the wiring pattern 3 formed on the front surface side, and the external connection terminals 2 and the wiring pattern 3 are also formed. Are electrically connected to each other by a through hole 4. Further, a recess 6 for dropping and arranging the semiconductor element 5 is formed at a position shifted from the center of the wiring board 1 to one side of the x-axis and the y-axis. In addition, on the front surface side of the wiring board 1, a solder resist 7 made of epoxy resin is formed on the wiring pattern 3 so as to surround the outer peripheral portion of the wiring board 1. When the solder resist 7 is formed, a part of the solder resist 7 is poured into the through hole 4 to be closed.

When the semiconductor element 5 is mounted on the wiring board 1, the semiconductor element 5 is first placed in the recess 6 in a state of being dropped. Next, an electrical connection is made between the semiconductor element 5 and the wiring pattern 3 with a gold wire 18, and then a molding resin 8 is injected into the inside surrounded by the solder resist 7 to perform transfer molding. A resin-sealed circuit board is formed by sealing with resin 8 (see FIG. 4). Further, after the molding, the groove 9 having a substantially V-shaped cross section is formed vertically and horizontally from above the molding resin 8 and escapes from the bonding post 3a of the wiring pattern 3 (at a position above the recess 6 in the horizontal direction). 2 on the left side of the recess y
One of the grooves 9 is formed in parallel with the axis, and a part of the groove 9 corresponds to the recess 6. The groove 9 reduces the Young's modulus so that the wiring board 1 can be easily bent or broken, and the external force applied to the semiconductor element 5 is absorbed by the bending.
Thereby, the effect of the groove 9 can be improved. FIG. 4 is a vertical cross-sectional side view showing the state after the semiconductor element 5 is thus resin-sealed.

[0022]

As described above, according to the present invention,
In the resin-sealed circuit board, when the external force is applied, the center O
It can be said that the center O is the weakest portion against an external force while the stress is maximized at the point where it is destroyed, and the center O is the weakest portion against the external force. Axis) and the vertical direction (y-axis), both of which are arranged in a recess formed at positions shifted to one side, the center where the semiconductor element is arranged is separated from the center of the wiring board, and the recess is surrounded. The post formed on the provided wiring pattern is adjacent to the side of the recess on the side most displaced from the center O of the wiring board, that is, the center O of the wiring board which is not easily affected by bending stress. Since the semiconductor element is arranged in the most distant position from the wiring board in one direction, even if the space between the wiring board and the mold resin is broken, the amount of the damage is small and the gold wire is not broken. To prevent Kill. This improves reliability.

In the case where a wiring pattern is provided around the cavity of the transfer molding die and a solder resist is provided so as to cover the wiring pattern, the surface of the solder resist with which the molding die abuts. Is smoothed, and it is securely held by the mold,
Flush during injection can be prevented.

When a groove for lowering the Young's modulus is provided on the surface of the mold resin, and when the groove is formed so that the range of the recess extends to the position of the groove, bending and breakage at the groove portion are easy. The obtained external force can be well absorbed to reduce the influence on the semiconductor element and the like. Further, when the groove is provided avoiding the bonding post, it is possible to prevent the gold wire from being broken at the time of bending and breaking, and the reliability is further improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a resin-sealed circuit board according to a first embodiment of the present invention before being resin-sealed.

FIG. 2 is a sectional view showing the resin-sealed circuit board according to the first embodiment of the present invention in a resin-sealed state.

FIG. 3 is a plan view showing a resin-sealed circuit board according to a second embodiment of the present invention before being resin-sealed.

FIG. 4 is a sectional view showing a resin-sealed circuit board according to a second embodiment of the present invention in a resin-sealed state.

FIG. 5 is a plan view showing an example of a conventional resin-sealed circuit board in a state before resin sealing.

FIG. 6 is a cross-sectional view showing an example of a conventional resin-sealed circuit board in a resin-sealed state.

FIG. 7 is a plan view showing another example of a conventional resin-sealed circuit board in a state before resin sealing.

FIG. 8 is a cross-sectional view showing another example of a conventional resin-sealed circuit board in a resin-sealed state.

FIG. 9 is a schematic view of a fracture strength test shown in a state before applying a load.

FIG. 10 is a schematic diagram of a fracture strength test shown in a state where a load is applied.

11 is an enlarged view of part A of FIG.

[Explanation of symbols]

 1 Wiring Board 3 Wiring Pattern 5 Semiconductor Element 6 Recess 7 Solder Resist 8 Mold Resin 18 Gold Wire

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01L 23/31 H05K 3/28 G

Claims (6)

[Claims] 1. A wiring board, a recess formed at a position displaced from the center of the wiring board, a semiconductor element arranged in the recess with its center offset from the center of the wiring board, and the wiring. A resin having a wiring pattern formed on one surface side of the substrate, connecting the bonding post of the wiring pattern and the semiconductor element with a gold wire, and sealing the surface of the wiring substrate with a mold resin. In the encapsulated circuit board, the resin-encapsulated circuit board is characterized in that the bonding posts are provided outside the recess farthest from the center of the wiring board and along the recess. 2. The semiconductor element is provided such that an end of the semiconductor element is arranged at a position of 1.4 mm or less in a horizontal direction and 2.25 mm or less in a vertical direction from an outer shape of a wiring board. 1. The resin-sealed circuit board according to 1. 3. The resin-sealed circuit board according to claim 1, wherein the wiring pattern is provided around a cavity of a transfer mold molding die, and a solder resist is provided so as to cover the wiring pattern. 4. The resin-sealed circuit board according to claim 3, wherein a groove is provided on the surface of the mold resin, and the recessed region extends to the position of the groove. 5. The resin-sealed circuit board according to claim 3, wherein the groove is provided so as to avoid the bonding post. 6. A wiring board, a recess formed at a position displaced from the center of the wiring board, a semiconductor element arranged in the recess with its center offset from the center of the wiring board, and the wiring. A resin having a wiring pattern formed on one surface side of the substrate, connecting the bonding post of the wiring pattern and the semiconductor element with a gold wire, and sealing the surface of the wiring substrate with a mold resin. In the method for manufacturing a sealed circuit board, a wiring pattern is provided around the cavity of the transfer mold molding die, and a solder resist is provided so as to cover the wiring pattern, and the mold is placed on the solder resist surface. A method of manufacturing a resin-sealed circuit board, characterized in that a mold resin is injected in a state of abutting and sandwiching.