JP3281838B2 - Circuit board with shield case and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board for a high-frequency circuit, a digital circuit, or the like, and more particularly to a circuit board having a shield case soldered over a plurality of circuit chips and a method of manufacturing the same.

[0002]

2. Description of the Related Art For example, in a high-frequency circuit board mounted on a radiotelephone, as shown in FIG.
A plurality of circuit chips (2) and (2) are provided on the surface of the solder layer (84), respectively.
And these circuit chips (2)
Cover the shield frame (37) and shield cover (3)
The shield case (39) made of (8) is joined by a soldering part (85) by manual work or robot hand.

In manufacturing the circuit board shown in FIG. 8, first, a predetermined cream solder pattern is formed on the surface of a printed wiring board (10), and a plurality of circuit chips (2) and (2) are formed on the cream solder pattern. After mounting, the printed wiring board
(10) is subjected to a batch reflow treatment in a reflow furnace. Thereby, the plurality of circuit chips (2) and (2) are soldered to the surface of the printed wiring board (10). Then, cover the circuit chips (2) and (2) on the printed wiring board (10) with the shield frame (3).
7) is soldered, and finally a shield cover (38) is attached to the shield frame (37).

[0004]

However, in the above-mentioned method for manufacturing a circuit board, a step of soldering a plurality of circuit chips (2) and (2) to the surface of the printed wiring board (10);
After that, two soldering steps of a step of soldering the shield frame (37) on the printed wiring board (10) are performed, so that not only a large number of man-hours but a long cycle time,
Since equipment for soldering is required in each step, capital investment is increased, and there is a problem that a large space is required for installation of these equipment. An object of the present invention is to reduce the number of manufacturing steps and the number of manufacturing facilities in a circuit board on which a plurality of circuit chips and a shield case are soldered.

[0005]

A circuit board provided with a shield case according to the present invention comprises a plurality of circuit chips (2) on at least one surface of a printed wiring board (1) and these circuit chips (2). The covering shield case (3) is soldered by batch reflow processing. Where the shield case
(3) is a shield frame surrounding a plurality of circuit chips (2)
(31) and a shield cover (32) for closing the central opening (30) of the shield frame (31).

In the circuit board, a plurality of circuit chips
(2) and the shield frame (31) of the shield case (3) are simultaneously soldered by the batch reflow process, so that the shield case (3) and the circuit chip (2) are provided on the surface of the printed wiring board (1). ), A bonding solder layer having a uniform thickness is formed. Due to the uniform bonding solder layer between the printed wiring board (1) and the shield case (3),
The shield effect of the shield case (3) is sufficient.

A method for manufacturing a circuit board having a shield case according to the present invention is a method for manufacturing a circuit board according to the present invention, wherein in the first step, a substrate (4) to be a printed wiring board (1) is used. ), A first cream solder pattern (81) to which a plurality of circuit chips (2) are to be joined by screen printing or the like, and a second cream solder pattern to which a shield frame (31) is to be joined. (8) is formed. Then the second
In the process, the plurality of circuit chips (2) are mounted on the first cream solder pattern (81), and the shield frame (3) is mounted.
With the shield frame (31) fitted in a frame-shaped jig (5) capable of correcting the shape by clamping the 1) from the surroundings, the shield frame (31) is attached to the second cream solder. Mount on pattern (8). Subsequently, in a third step, a plurality of circuit chips
The substrate (4) on which (2) and the shield frame (31) are mounted is heated in a reflow furnace (71) to perform a batch reflow process. In the fourth step, the shield frame on the substrate (4)
After removing the jig (5) from (31), attach the shield cover (32) to the shield frame (31), and
A printed wiring board (1) on which (2) and a shield case (3) are surface-mounted is obtained.

In particular, the shield case (3) is connected to the shield frame (3).
1) and the shield cover (32), the shield frame (31) is easily deformed. In the second step, the deformed shield frame (31) is applied to the cream solder pattern of the printed wiring board (1).
When mounted on (8), the shield frame (31) does not adhere to the cream solder pattern (8), and there is a possibility that soldering failure may occur in the subsequent batch reflow process (third step). On the other hand, in the method for manufacturing a circuit board of the present invention, the deformation of the shield frame (31) is corrected by fitting the shield frame (31) into the jig (5). By mounting the shield frame (31) on the substrate (4), the shield frame (31) comes into close contact with the cream solder pattern (8).
Good soldering is performed together with the circuit chip (2).

In a specific configuration, the jig (5) used in the second step has a weight necessary for bringing the shield frame (31) into close contact with the second cream solder pattern (8). . According to the specific configuration, in the second step, the shield frame (31) fitted to the jig (5) is replaced with the cream solder pattern (8).
When mounted above, the weight of the jig (5) lowers the shield frame (31) onto the cream solder pattern (8), so that the shield frame (31) does not rise. As a result, the shield frame (31) is more securely adhered to the cream solder pattern (82).

In another specific configuration, the jig (5) used in the second step includes a plurality of positioning pins (52) (53).
(53) is projected downward, while the substrate (4) has a plurality of positioning holes through which the positioning pins (52), (53) and (53) pass.
(42) (43) (43) have been established. According to the specific configuration, after the shield frame (31) is fitted to the jig (5) in the second step, the positioning pins (52), (53), and (53) of the jig (5) are removed. substrate
By mounting the shield frame (31) on the printed wiring board (1) by passing it through the positioning holes (42), (43), and (43) of (4), the jig (5) can be mounted on the substrate (4). , And as a result, the shield frame (31) is accurately positioned with respect to the cream solder pattern (8) of the substrate (4).

In still another specific configuration, the substrate (4) is placed on a heat-resistant substrate support (6) having an engagement portion of the substrate (4) formed on the surface thereof, The substrate (4) is transported to the third step while supporting both ends of (6). Conventionally, when the substrate (4) is transported to each step, both ends of the substrate (4) are directly supported and transported. In this case, in particular, a batch reflow process is performed in the third step. At this time, the substrate (4) may be deformed by its own weight and heat. However, according to the above specific configuration, the substrate (4) is placed on the heat-resistant substrate receiving table (6).
Since the substrate (4) is transported to the third step in the state where (4) is engaged, the own weight of the substrate (4) is received by the substrate receiving base (6), and the substrate (4) is received in the third step. There is no fear that thermal deformation will occur.

A plurality of circuit chips (2) of the board (4) and the shield frame are mounted on the board support (6) in a state where the board (4) is engaged with the engaging portion with the board (4). A window (61) into which (31) should enter has been opened. Substrate (4) also has a circuit chip (21) on the back
After the soldering of the shield frame (31) and the circuit chip (2) according to the present invention is completed, the substrate (4) is turned over, and a cream solder pattern is formed on the back surface, and the circuit chip is formed. In this case, it is necessary to carry out mounting and batch reflow processing. At this time, the substrate (4) moves the circuit chip (2) and the shield frame (31) downward from the window (61) of the substrate support (6). In the protruding state, it can be engaged with the surface of the substrate receiving base (6). Here, the shield frame (31) is held by the opening edge of the window (61), and is prevented from falling off.

[0013]

According to the circuit board provided with the shield case and the method of manufacturing the same according to the present invention, a plurality of circuit chips and a shield frame are soldered simultaneously by batch reflow processing using common equipment. In addition, the number of man-hours can be reduced as compared with the related art, and the manufacturing equipment can be reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a high-frequency circuit board of a radio telephone will be specifically described with reference to the drawings. FIG. 1 shows a high-frequency circuit board according to the present invention. A plurality of circuit chips (2) constituting a high-frequency circuit are surface-mounted on a printed wiring board (1).
A shield case (3) including a shield frame (31) and a shield cover (32) is surface-mounted so as to cover these circuit chips (2).

As shown in FIG. 2, the plurality of circuit chips (2) have a plurality of leads via a solder layer (84).
Soldered to the surface of (1). Also, shield case
The shield frame (31) of (3) has flanges (33) and (33) at both ends, and the shield frame (3) includes the rear surface area of the flanges (33) and (33).
The entire area of the back surface of 1) is soldered to the surface of the printed wiring board (1) via the solder layer (84). Shield cover (3
2) is engaged with the shield frame (31) to close the central opening (30) of the shield frame (31). A plurality of circuit chips (21) that do not need to be shielded are soldered to the back surface of the printed wiring board (1) via a solder layer (84).

In the manufacture of the circuit board, in order to improve the production efficiency, as shown in FIG. 3, a separation groove (4) capable of separating the four printed wiring boards (1), (1), (1) and (1) is used. Four
The substrate (4) on which (1) is formed is used. On the surface of the substrate (4), two printed wiring boards (1) arranged on one diagonal line
A cream solder pattern (81) for soldering the circuit chip (2) and the shield frame (31) to (1).
(8) is formed, and 2 are arranged on the other diagonal line.
A cream solder pattern (82) for soldering the circuit chip (21) that does not require the shield is formed on the printed wiring boards (1) and (1). A well-known screen printing technique is used for forming the cream solder patterns (8), (81) and (82). As will be described later, the same cream solder pattern (8) (8) as the pattern shown in FIG.
1) By forming (82) and performing the same soldering process consisting of mounting of a circuit chip and batch reflow processing on each of the front and back surfaces of the board (4), four circuit boards at a time Fabrication is possible. The substrate (4) has a plurality of positioning holes (42), (43), and (44) to be provided for positioning described later at predetermined positions.

Next, a jig (5) shown in FIG.
With the (31) fitted, the shield frame (31) is
It is mounted on the cream solder pattern (8) of (4) (see FIGS. 5 and 6). A plurality of circuit chips (2) are already mounted on the printed wiring board (1). A well-known mounter can be used for mounting the shield frame (31). The jig (5) is made of brass, and has a stepped engaging surface (51) on its inner peripheral surface to correct the deformation of the shield frame (31) by pressing the shield frame (31) from the periphery. Are formed, and a ball plunger (9) for pressing the side surface of the shield frame (31) that can be clamped is attached. The ball plunger (9) accommodates a ball (91) and a spring (92) in a through hole formed in the jig (5) as shown in FIG. By shield frame
The spring (92) is urged inward of (31), and the spring (92) is prevented from falling off by a screw (93).

As shown in FIG. 4, the jig (5) has one relatively thin positioning pin (52) and two relatively thick positioning pins (53) (53) facing downward. The narrow positioning pin (52) projects through the hole (36) of the projection (34) projecting from one of the flanges (33) of the shield frame (31) to form the substrate (4). It is possible to fit into one of the positioning holes (42). Also, the two thick positioning pins (53) and (53) are mounted on the board (4).
It is possible to fit into each of the positioning holes (43) and (43). The jig (5) has a weight (about 60 g) for lowering the clampable shield frame (31) onto the cream solder pattern (8) with a sufficient pressure. On the other hand, the weight of the shield frame (31) is about 4 g.

As described above, the positioning pins (52) (5) of the jig (5) are used.
3) The shield frame fitted to the jig (5) by fitting the (53) into the positioning holes (42), (43), and (43) of the substrate (4).
(31) is accurately mounted on the cream solder pattern (8) of the substrate (4). The deformation of the shield frame (31) has been corrected by the jig (5), and the back surface of the shield frame (31) has a cream solder pattern due to the weight of the jig (5).
(8) Since the pressure is reduced upward, the entire area of the back surface of the shield frame (31) comes into close contact with the surface of the cream solder pattern (8) without causing the floating of the shield frame (31). .

As shown in FIG. 5, a plurality of circuit chips (2) requiring shielding and a jig (5) are fitted on two printed wiring boards (1) (1) of a substrate (4). The mounted shield frame (31) and the other two printed wiring boards (1)
(1) A circuit chip (21) that does not need to be shielded is mounted thereon, and then the board (4) is engaged with the board (6). Conveyor on both ends of (7)
And transported to the batch reflow process. The substrate pedestal (6) is made of heat-resistant bakelite, and has a recess (64) with which the substrate (4) is to be engaged. Already shield frame (3
1) and a pair of first windows (61) and (61) for releasing a plurality of circuit chips (2) when they are soldered;
When a plurality of circuit chips (21) are already soldered to the back surface of (4), a pair of second windows (62) (6)
2) has been established. At the corner of the recess (64),
Positioning pieces (63) (63) into which the two positioning holes (44) and (44) of (4) fit are protruded.

The board receiving table (6) is used not only for transferring the board (4) from the chip mounting step to the batch reflow step, but also for transferring the board (4) from the cream solder pattern printing step to the chip mounting step. Also used when transporting.

The substrate (4) is transported by the conveyor (7) together with the substrate cradle (6) to the next batch reflow step.
The substrate (4) is accommodated in a reflow furnace (71) as shown in FIG. By heating in the reflow furnace (71), the cream solder patterns (8) and (81) are melted, and the shield frame (31) and the circuit chip
(2) will be soldered on the substrate (4). At this time, since the jig (5) has high thermal conductivity, the heat given in the reflow furnace (71) is not taken away by the jig (5), and the cream solder pattern (8) ( 81) is fully heated. Further, since the back surface of the shield frame (31) is in close contact with the surface of the cream solder pattern (8), the soldering is performed well, and there is no fear that a defect occurs. In addition, the board support
(6) has sufficient heat resistance and strength.
Even when the load of (4) is applied, there is no risk of thermal deformation, and the substrate (4) is securely supported in a horizontal posture.

From the substrate (4) that has undergone the batch reflow treatment, a jig
By removing (5), as shown in FIG. 7, two shield frames (31) (31) and a plurality of circuit chips (2) (2)
A substrate (4) to which (1) is soldered is obtained. Next, the substrate (4) is turned over, and the above-described printing step of the solder paste pattern, the chip mounting step, and the batch reflow step are performed. (31) (31) and a plurality of circuit chips (2) and (21) are soldered.

When performing the screen printing of the cream solder pattern on the back surface of the substrate (4), since the jig (5) is removed, there is no protrusion on the back surface of the substrate (4), and there is no problem in screen printing. . When performing the batch reflow process with the back surface of the substrate (4) facing upward, the shield frame (31) is already soldered to the downward surface of the substrate (4), and the shielding frame (31) is placed in the reflow furnace (71). The heating causes the solder layer of the shield frame (31) to slightly soften, but the flanges (33) (33) protruding on both sides of the shield frame (31) form the first window ( 61), the shield frame (31) is reliably prevented from dropping. Since the circuit chip (2) is extremely lightweight, there is no fear of falling off.

Finally, the four printed wiring boards (1), (1), (1) and (1) are separated from the board (4), and a shield cover (32) is attached to the shield frame (31) of each printed wiring board. By mounting, four circuit boards provided with the shield case (3) shown in FIG. 2 are obtained.

According to the method for manufacturing a circuit board, a plurality of circuit chips (2) and a shield frame (3) of a shield case (3) covering these circuit chips (2) are provided on the surface of the printed wiring board (1). 31) can be soldered simultaneously by batch reflow processing, so there is no need for special equipment such as manual work or a robot hand for soldering the shield frame body (31) as in the conventional case. The number of manufacturing steps can be reduced, the cycle time can be significantly reduced, and the manufacturing equipment can be reduced. Further, in the circuit board obtained by this, a solder layer (84) having a uniform thickness is formed between the printed wiring board (1) and the shield case (3). The soldering is performed with higher reliability than that of. As a result, a sufficient shielding effect can be obtained by the shield case (3).

The configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims. For example, in the above embodiment, the manufacturing method of the present invention is applied to the substrate (4) from which the four printed wiring boards (1) can be separated. It is possible to implement the method for the substrate 1). In the above embodiment, the printed wiring board
Although the double-sided circuit board provided with the circuit chip (21) on the back surface of (1) is intended, the present invention can be applied to a single-sided circuit board provided with the circuit chip (2) on only one side.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view in which a part of a circuit board according to the present invention is broken.

FIG. 2 is a cross-sectional view of the circuit board.

FIG. 3 is a perspective view of a substrate serving as four printed wiring boards.

FIG. 4 is an exploded perspective view of a substrate, a shield frame and a jig.

FIG. 5 is an exploded perspective view of a substrate provided with a shield frame and a jig and a substrate receiving base.

FIG. 6 is an enlarged sectional view showing a main part of a substrate provided with a shield frame and a jig.

FIG. 7 is a perspective view of a substrate that has undergone a batch reflow process.

FIG. 8 is a sectional view of a conventional circuit board.

[Explanation of symbols]

 (1) Printed wiring board (2) Circuit chip (21) Circuit chip (3) Shield case (31) Shield frame (32) Shield cover (4) Board (5) Jig (51) Clamping surface (6) Board support (8) Cream solder pattern (81) Cream solder pattern (84) Solder layer

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasumi Urakami 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Shigemitsu Matsuyama 2-chome Keihanhondori, Moriguchi-shi, Osaka No. 5-5 Inside Sanyo Electric Co., Ltd. (72) Shuzo Yoshidome 2-5-5 Keihanhondori 2-chome, Moriguchi City, Osaka Prefecture (72) Inventor Tatsushige Miyamoto 2 Keihanhondori, Moriguchi City, Osaka Prefecture No. 5-5 Sanyo Electric Co., Ltd. (72) Inventor Tadashi Ishiyama 2-5-5 Keihan Hondori, Moriguchi City, Osaka Prefecture Sanyo Electric Co., Ltd. (56) References JP-A-7-240591 (JP, A JP-A-7-231159 (JP, A) JP-A-4-340790 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05K 9/00 H05K 3/34 507

Claims (5)

(57) [Claims] A plurality of circuit chips (2) are soldered to at least one side of a printed wiring board (1), and a shield frame (31) and a shield frame surrounding the circuit chips (2) are provided. Shield cover to close the central opening (30) of (31)
A method of manufacturing a circuit board to which a shield case (3) consisting of (32) is soldered, wherein a plurality of circuit chips (2) are provided on a surface of a board (4) serving as a printed wiring board (1). A first step of forming a first cream solder pattern (81) to be joined and a second cream solder pattern (8) to be joined to the shield frame (31); ) To the first cream solder pattern (8
1) A frame-shaped jig (5) that can be mounted on the top and the shape can be corrected by pressing the shield frame (31) from the periphery.
With the shield frame (31) fitted in the shield frame (3)
A second step of mounting (1) on the second cream solder pattern (8); and mounting the substrate (4) on which the plurality of circuit chips (2) and the shield frame (31) are mounted in a reflow furnace (71). A third step of performing a batch reflow process by heating in step (1), and removing the jig (5) from the shield frame (31) on the substrate (4), and then attaching the shield cover (32) to the shield frame (31). Mounting a plurality of circuit chips (2) and a shielded case (3) to obtain a printed wiring board (1) surface-mounted. 4. A method of manufacturing a circuit board comprising a shielded case. 2. The jig (5) used in the second step has a weight necessary for bringing the shield frame (31) into close contact with the second cream solder pattern (8). 3. The method for manufacturing a circuit board according to 1. The jig (5) used in the second step has a plurality of positioning pins (52) (53) (53) projecting downward, while the substrate (4) has 3. The method for manufacturing a circuit board according to claim 1, wherein a plurality of positioning holes (42), (43), (43) through which the positioning pins (52), (53), (53) pass are formed. 4. A substrate (4) is placed on a heat-resistant substrate support (6) having an engaging portion of the substrate (4) formed on the surface, and both ends of the substrate support (6) are 4. The method of manufacturing a circuit board according to claim 1, wherein the substrate is supported and transported to a third step. 5. A window (61) for allowing a plurality of circuit chips (2) and a shield frame (31) to penetrate into an engaging portion of the substrate (4) in the substrate receiving stand (6). The method for manufacturing a circuit board according to claim 4.