JP4001778B2 - Circuit module and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit module and a method for manufacturing the circuit module, and more particularly to a resin-coated circuit module and a method for manufacturing the circuit module.
[0002]
[Prior art]
In many cases, the manufacture of a circuit module starts with preparing an aggregate circuit board having a size corresponding to the number of the circuit modules. On the mounting surface of the collective circuit board, a plurality of circuit modules are assembled by mounting electronic components, and after predetermined processing is finished, the circuit modules are cut into individual circuit modules. This manufacturing method is common because it is more efficient because a multiple of circuit modules can be manufactured at a time compared to the case of manufacturing a single circuit module.
[0003]
The collective circuit board is generally cut by a dicing apparatus. The dicing apparatus is configured to cut a collective circuit board supported on a table with a rotating blade. At least one of the table or the rotating blade can move in, for example, the X-axis direction and the Y-axis direction orthogonal to the X-axis direction, and the circuit module is cut out by repeating this movement.
[0004]
[Problems to be solved by the invention]
Since many of the above-described collective circuit boards use ceramics, they have high rigidity but are brittle. Dicing should be performed in the shortest possible time in order to shorten the manufacturing time. For this purpose, it is necessary to increase the cutting speed, but if this is increased, chipping may occur due to the brittleness and a defective product may be generated in the circuit module. In addition, there is a risk that electronic components existing around the cutting portion may be adversely affected by the cutting vibration by the rotating blades or may be dropped off, which is one of the causes of defective circuit modules.
[0005]
[Problems to be solved by the invention]
The problem to be solved by the present invention has been made in consideration of the above-mentioned circumstances, and prevents the chipping and vibration when cutting the collective circuit board from adversely affecting electronic components, and also preventing the components from falling off. Accordingly, it is an object to provide a high-quality circuit module and to provide a method for manufacturing such a circuit module.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the inventor adopted the following means. It should be noted that the definitions of terms used in the description of the invention described in any claim shall be applied to the invention described in other claims as long as possible in nature.
[0007]
(Characteristics of the invention described in claim 1)
A circuit module according to a first aspect of the present invention includes a circuit board including an electronic component on a mounting surface and an outer peripheral substrate end surface, and a first resin layer including an outer periphery having a first resin end surface that is flush with the substrate end surface. A part of the first resin layer is interposed between the mounting surface and the electronic component . According to the circuit module of the first aspect , the cutting line (cutting line) when the collective circuit board is cut by the rotating blade is on the first resin layer. The substrate end face and the first resin end face form the same plane because the circuit board and the first resin layer are cut simultaneously. Since the cutting line is on the first resin layer, the impact caused by the contact of the rotating blade is reduced compared to the case where the cutting line is not provided, and it is difficult to transmit to the collective circuit board. That is, the first resin layer functions as a buffer material. This buffering effect effectively prevents chipping of the circuit module. Since a part of the first resin layer is interposed between the mounting surface of the circuit board and the electronic component mounted thereon, solder melted by reflow or the like does not flow between them. Short circuit due to solder inflow is also prevented. That is, chipping prevention and solder short-circuit prevention can be realized at the same time.
[0008]
Circuit module according to the invention as set forth in claim 1 further comprising a second resin layer comprising a second resin end surface of the first resin end surface flush with the outer periphery, the second resin layer, at least the first The upper surface of the resin layer and the outer surface of the electronic component are covered. According to this circuit module, the first resin layer and the electronic component can be prevented from coming into contact with the outside. Thereby, an electronic component etc. are protected more physically and electrically than the case where the 2nd resin layer is not provided. In particular, when the solder fillet is not completely covered only with the first resin layer, it is possible to effectively prevent the molten solder fillet from flowing out during reflow by covering the solder fillet with the second resin layer. Reliable protection and prevention of solder fillet outflow contribute to effective prevention of circuit module quality degradation. The second resin layer also has a function of buffering the contact impact of the rotating blade, like the first resin layer.
[0009]
(Characteristics of the invention described in claim 2 )
Circuit module according to the invention described in claim 2 is obtained by adding a limited configuration of the circuit module according to claim 1, by constituting the first resin layer by the first resin in the first viscosity during the filling In addition, the second resin layer is constituted by a second resin having a second viscosity higher than the first viscosity at the time of filling. The first resin layer needs to be interposed between the mounting surface and the electronic component, and preferably has a low viscosity suitable for it. On the other hand, since the second resin layer coats electronic components and the like, it is easier to coat when the viscosity is higher than that of the first resin layer. Therefore, by making the former viscosity at the time of filling lower than that of the latter, each resin layer can be efficiently formed by changing the viscosity.
[0010]
(Characteristics of the invention described in claim 3 )
The circuit module manufacturing method according to the invention described in claim 3 includes the following four steps. In the first step, an assembly circuit board is prepared in which a plurality of circuit modules are assembled by mounting electronic components on a mounting surface. Next, a predetermined number of Y-axis cuttings perpendicular to the X-axis cutting line and the predetermined number of X-axis cutting lines on the mounting surface are penetrated between the electronic component and the mounting surface. Fill on line. This is the second step. In the third step, the filled first resin is cured under predetermined conditions. In the final fourth step, the aggregate circuit board is divided into a plurality of circuit modules by dicing cutting the X-axis cutting line and the Y-axis cutting line filled with the first resin. The cutting order may be preceded in either the X-axis direction or the Y-axis direction, or may be performed alternately if possible.
[0011]
According to the circuit module manufacturing method of the third aspect, the divided circuit modules are rectangular when viewed from a plane having four outer peripheral end faces. Furthermore, since at least the dicing cut process is performed in common in the manufacture of each circuit module, a large number of circuit modules can be manufactured at a time as compared with the case where the circuit modules are manufactured individually. In addition to this, since the collective circuit board is cut by the rotating blade on the cutting line (cutting line) filled with the first resin layer, the first resin layer functions as a cushioning material and the contact impact of the rotating blade is applied. Relax and make it difficult to convey to the collective circuit board. By this buffering effect, chipping of the circuit module is effectively prevented, and the manufactured circuit module can be made high quality accordingly. Part of the first resin layer is interposed between the mounting surface of the circuit board and the electronic component mounted thereon to prevent a short circuit due to solder flowing during reflow. By this single process, prevention of chipping and prevention of short circuit are realized at the same time.
[0012]
Method of manufacturing a circuit module according to the invention described in claim 3, also, in the above second step, putting a set circuit board filled with the first resin into the mold, a first viscosity possessed by the first resin A step of coating the electronic component by adding a second resin having a higher second viscosity into the mold and molding the second resin is added. That is, the collective circuit board covered with the first resin is covered with the second resin and then dicing cut. By providing the second resin layer, the first resin layer and the electronic component can be prevented from coming into contact with the outside. As a result, the electronic components and the like are more reliably protected physically and electrically, which contributes to maintaining the high quality of the circuit module. In particular, when the solder fillet is not completely covered only with the first resin layer, it is possible to effectively prevent the molten solder fillet from flowing out during reflow by covering the solder fillet with the second resin layer. Reliable protection and prevention of solder fillet outflow contribute to effective prevention of circuit module quality degradation. Further, like the first resin layer, the second resin layer also functions to buffer the contact impact of the rotating blade.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, a circuit module according to an embodiment of the present invention and a manufacturing method thereof will be described with reference to the drawings. Embodiments of the present invention will be described. FIG. 1 is a plan view of a circuit module. 2 is a cross-sectional view of the circuit module shown in FIG. FIG. 3 is a diagram showing a manufacturing process of the circuit module shown in FIG. FIG. 4 is a plan view of the collective circuit board. FIG. 5 is a perspective view showing a state of cutting.
[0014]
(Schematic structure of circuit module)
A schematic structure of the circuit module will be described with reference to FIGS. The circuit module 1 includes a circuit board 3 having land electrodes 5 on a mounting surface 3f, an electronic component 21 mounted on the mounting surface 3f, a first resin layer 7 made of a first resin, and a second resin. A second resin layer 9. Circuit board 3, is formed in a rectangular having a fourth end surface when viewed in plan as shown in FIG. Reference numerals 3 a to 3 d indicate four substrate end faces of the circuit board 3. The circuit board 3 is a board in which a conductive wiring pattern is formed on an insulating substrate made of ceramic, epoxy, or the like mainly by a chemical method such as a printing method or etching. A land electrode is included in the wiring pattern.
[0015]
The electronic component 21 has terminal electrodes (end surface electrodes) 21 b and 21 b on the side surface of the chip-shaped component main body 21 a, and the terminal electrodes 21 b and 21 b are connected to the land electrode 5 via a solder fillet 23. . As electronic parts having terminal electrodes 21b and 21b, passive parts such as resistors, capacitors, coils, etc. are common, but ICs and other active elements may have end face electrodes. The electronic components mounted on the circuit module 1 shown in FIGS. 1 and 2 are only the electronic components 21 and 21 having the terminal electrodes 21b and 21b. In addition to these, the electronic components having terminals only on the bottom surface, such as flip chips and bare chips. Does not interfere with the mounting of parts.
[0016]
(First resin layer)
The first resin layer 7 is formed by curing the first resin by a process described later, and a part of the first resin layer 7 is formed in the gaps 25, 25 between the electronic component 21 (component main body 21 a) and the land electrode 5. Is also interposed. This is to prevent the terminal electrodes 21b and 21b from being short-circuited by contact between the solder fillets 23 and 23 melted and flowing out of the circuit module 1 when the circuit module 1 is reflowed. Therefore, the liquid first resin must be able to penetrate between the terminal electrodes 21b and 21b. That is, the size of the gap 25 formed between the two differs depending on the shape of the electronic component, but is generally about 20 microns and is very narrow. The liquid first resin penetrates into the gap 25 by capillary action, but cannot penetrate as if the viscosity at this time is not sufficiently low. In order to make it penetrate | invade rapidly, it is good to set the viscosity (1st viscosity) of 1st resin in this embodiment to about 2-10 PaS at normal temperature at the time of filling (application | coating). The first resin layer 7 shown in FIG. 2 covers the solder fillets 23 and 23 halfway, but may be formed so as to cover all of the solder fillets 23 and 23 and the entire electronic component 21. As the first resin, an epoxy-based or acrylic-based thermosetting resin is used, but other resins may be used. The first resin layer 7 includes first resin end surfaces 7 a to 7 d that form the same plane as the substrate end surfaces 3 a to 3 d of the circuit board 3.
[0017]
(Second resin layer)
The second resin layer 9 covers at least the upper surface of the first resin layer 7 and covers the electronic components 21 and 21 on the upper surface 3 a of the circuit board 3. The second resin layer 9 shown in FIG. 2 is formed in a quadrangle when the figure is viewed from the front. However, since this is formed by transfer molding as will be described later, the upper base is only flat. Absent. As long as the electronic components 21 and 21 are covered, that is, as long as the electronic components 21 and 21 are not brought into contact with the outside, the shape of the second resin layer 9 is not limited. Providing the second resin layer 9 also prevents the solder fillet 23 from flowing out during reflow. That is, when the first resin layer 7 does not completely cover the solder fillets 23 and 23 and a part thereof is exposed, if the exposed portion is covered with the second resin layer 9, the solder melted at the time of reflowing The outflow of the fillets 23, 23 can be effectively prevented.
[0018]
The second resin at the time of filling before curing has a viscosity (second viscosity) higher than the viscosity of the first resin (first viscosity). This is because a resin that can be molded into a shape that can cover the electronic components 21, 21, and the like is required instead of penetrating into a narrow gap like the first resin. A resin having a viscosity of about 11 to 50 PaS when it is liquid, that is, when the molding temperature is set to 150 to 170 ° C., for example, is suitable. In this embodiment, for example, an epoxy resin, an acrylic resin, a liquid crystal polymer, or a thermoplastic resin in which a filler is mixed is used as such a resin. It is not always necessary to mix the filler, but if this is mixed and the coefficient of thermal expansion between the second resin layer 9 and the circuit board 3 is matched, the warpage of the circuit module 1 during reflow can be effectively suppressed. Good. The second resin layer 9 includes second resin end surfaces 9 a to 9 d that form the same plane as each of the first resin end surfaces 7 a to 7 d of the first resin layer 7. That is, the second resin end surfaces 9a to 9d are flush with the substrate end surfaces 3a to 3d of the circuit board 3 with the first resin end surfaces 7a to 7d interposed therebetween.
[0019]
(Circuit module manufacturing procedure)
The manufacturing procedure (manufacturing method) of the circuit module 1 will be described with reference to FIG. This manufacturing procedure is divided into five steps. In the following, description will be given in order. First, in the first step, as shown in FIG. 3A, the mounting surface 101 of a large substrate having a size corresponding to the number of circuit modules to be obtained, that is, the number of circuit modules to be obtained after cutting. A collective circuit board 101 in which a plurality of circuits are gathered is prepared by mounting a number of electronic components corresponding to the number on the top. That is, the collective circuit board 101 is composed of the circuit boards 3,. . . Is a collection of At this time, each of the circuit boards 3 includes electronic components 21 and 21 on its mounting surface 3f, and these electronic components 21 and 21 constitute a circuit together with other electronic components and the like not shown.
[0020]
Specifically, the electronic components 21, 21,. . . Are connected to the mounting surfaces 3f,. . . The upper land electrodes 5, 5,. . . Connect to. This connection is made by soldering. By soldering, the solder fillets 23, 23,. . . Is formed. As a result, the collective circuit board 101 which is an aggregate of the circuit boards 3 to which the electronic components 21 and 21 are soldered is obtained. When the collective circuit board 101 is prepared, the first step is finished. In the first step, although not shown in FIG. 3, a BGA (BALL GRID ARRAY) having a terminal electrode on the bottom surface, a bare chip, or the like may be soldered to the land electrode as necessary. Good. Furthermore, a rectangular external terminal or the like can be provided according to the shape and situation of a mother board or the like not shown.
[0021]
Next is the second step. As shown in FIG. 3B, in the second step, a first resin having a first viscosity is applied to the mounting surface 101f of the collective circuit board 101 prepared in the first step, and a nozzle 51 of a resin dispenser (not shown). To be mounted on the mounting surface 101f. As shown in FIG. 4, the nozzle 51 is configured to be movable in the X-axis direction (left-right direction on the paper surface) and the Y-axis (up-down direction on the paper surface). Specifically, by combine the movement of the moving and the Y-axis direction of the X-axis direction, the X-axis direction via the equal spacing pitch Px plurality of filling lines X1, X2, X3, on ... Xn In addition, the Y-axis direction is configured to be movable on the plurality of filling lines Y1, Y2, Y3,. As the nozzle 51 moves on these filling lines X1,..., Y1,... And continues to fill the first resin at that time, a grid pattern is formed on the mounting surface 101f of the collective circuit board 101. The resin line is formed.
[0022]
Here, attention is focused on the circuit module 1 indicated by a solid line in FIG. This shows the situation after the nozzle 51 has passed over the filling lines Y2, Y3, X1 and X2. As described above, since the first resin has a relatively low viscosity at the time of filling, the first resin flows on the mounting surface 3f (101f) almost simultaneously with the filling, and around the electronic components 21 and 21 as shown in FIG. When reached, surface tension wraps around their backside and surrounds them. The first resin surrounding the electronic components 21 and 21 permeates and penetrates between the electronic components 21 and 21 and the mounting surface 3f. This phenomenon is due to capillary action. Therefore, the periphery of the electronic components 21 and 21 is covered with the first resin, and the first resin is interposed in the gap between the mounting surface 3f below the electronic components 21 and 21. The first resin shown in FIG. 4 forms a flow line from the filling lines Y2, Y3, X1 and X2 to the electronic components 21 and 21 (although part of the mounting surface 3f is exposed), For example, the entire mounting surface 3f (101f) can be covered by increasing the filling amount of the first resin.
[0023]
Next, as the third step, the first resin is cured under predetermined conditions. This predetermined condition is slightly different depending on the viscosity and room temperature of the first resin and the size and material of the collective circuit board 101. For example, by heating for 1 hour under a temperature condition of 150 to 170 degrees C. It is preferred to cure. When curing is completed and the first resin layer 7 is formed, the third step is finished.
[0024]
Next is the fourth step. As shown in FIG. 3C, in the fourth step, the collective circuit board 101 on which the first resin layer 7 is formed is placed in a mold 53, filled with the second resin, and transfer molded. The second resin is filled in the mold 53 with the resin tablet 55 by the movement of the piston 57, and thereby, the second resin filled is pressurized and molded in the mold 53. During the molding, the second resin is cured. By curing the second resin, the electronic components 21, 21,. . . 2nd resin layer 9 which coats is completed. The fourth step is completed by taking out the completed circuit board 101 having the second resin layer from the mold 53. In this embodiment, since it is convenient for molding the second resin layers 9 and 9 ′, molding by transfer molding is performed, but it goes without saying that other molding methods can also be used. In addition, when not forming the 2nd resin layer 9, it can also skip this 4th process and can progress directly to the following 5th process.
[0025]
The fifth process, which is the last process, will be described with reference to FIGS. FIG. 5 shows a dicing device 61. The dicing device 61 is generally composed of a drive unit 63 for rotating the disk-shaped rotary blade 65 and a table 67 for placing the collective circuit board 101 to be cut. The table 67 can move in the X-axis direction (left-right direction) and the Y-axis direction (depth direction) shown in FIG. 5 and can be rotated 90 degrees in the plane direction to exchange the positions in the X-axis direction and the Y-axis direction. Accordingly, the relative position with respect to the rotating blade 65 can be changed two-dimensionally. The rotary blade 65 is configured to be movable up and down in the Z-axis direction (vertical direction) shown in FIG. Therefore, the collective circuit board 101 can be cut into a square shape by two-dimensional movement of the table 67 and vertical movement of the rotary blade 65.
[0026]
In a specific operation, first, the collective circuit board 101 is placed on the table 67 so that the mounting surface 101f is on the top. Next, the collective circuit board 101 is fixed on the table 67 by a fixture (not shown). This is to prevent the displacement of the filling line as a cutting line. Here, the table 67 is filled with filling lines X1, X2, X3,. . It moves according to Xn, and when it reaches a predetermined position, the rotary blade 65 is lowered and cut. Each filling line X1, X2, X3,. . When cutting on Xn is completed, the rotary table 67 is rotated 90 degrees to exchange the X-axis direction and the Y-axis direction. Once replaced, each filling line Y1, Y2, Y3,. . Cut Yn in the same procedure as above. On the contrary, the cutting in the X-axis direction may be performed after the cutting in the Y-axis direction.
[0027]
When the cutting in the X-axis direction and the Y-axis direction is finished, the collective circuit board 101 has a plurality of circuit modules 1,... Arranged in a grid-like cutting groove formed by cutting. . . Can be obtained. The fifth process is completed by picking up each circuit module 1 obtained in this way from the table 67. The circuit modules 1 do not fall apart due to the action of the adhesive tape 103 (see FIG. 3) provided on the bottom surface of the collective circuit board 101.
[0028]
(Effects specific to the embodiment)
Since a large number of circuit modules 1 obtained by the above steps can be obtained at a time, the circuit modules 1 can be manufactured much more efficiently than when manufactured one by one. Further, since the filling line and the cutting line of the first resin coincide with each other in manufacturing, the shock of the rotary blade 65 is hardly transmitted to the collective circuit board 101 due to the buffering effect of the first resin. By buffering the impact, it is possible to effectively prevent adverse effects on the electronic components due to chipping and vibration of the collective circuit board 101 (circuit board 3) that tend to occur at the time of cutting, and the dropout thereof. Contributes to the production of high-quality circuit modules with reduced Furthermore, by providing the second resin layer 9, it is possible to further improve the impact mitigation effect as compared with the case of only the first resin layer 7, and the solder fillets 23 and 23 are exposed from the first resin layer 7. In this case, it is possible to prevent solder from flowing out during reflow. That is, by providing the second resin layer 9, it is possible to provide a higher quality circuit module.
[0029]
【The invention's effect】
Due to the buffering effect of the first resin when cutting the collective circuit board, it is possible to prevent adverse effects on the electronic components due to chipping and vibration when cutting the collective circuit board, and also prevent the components from falling off. Thereby, a high quality circuit module can be provided. Further, by providing the second resin layer, the buffering effect is enhanced, and further preventing the outflow of solder during reflow when the solder fillet is exposed from the first resin layer, thereby providing a higher quality circuit module. be able to.
[Brief description of the drawings]
FIG. 1 is a plan view of a circuit module.
FIG. 2 is a cross-sectional view of the circuit module AA shown in FIG.
FIG. 3 is a schematic view showing a manufacturing procedure of the circuit module shown in FIG. 2;
FIG. 4 is a plan view of the collective circuit board.
FIG. 5 is a perspective view showing a state of cutting.
[Explanation of symbols]
1 Circuit module 3 Circuit board (printed wiring board)
5 Land electrode 7 First resin layer 9 Second resin layer 11 Terminal electrode 21 Electronic component 21b Terminal electrode 23 Solder fillet 25 Clearance 65 Rotating blade

Claims (3)

A circuit board having an electronic component on the mounting surface and an outer peripheral substrate end surface;
A first resin layer provided on the outer periphery with a first resin end surface flush with the substrate end surface;
A second resin layer provided on the outer periphery with a second resin end surface that is flush with the first resin end surface ;
Part of the first resin layer is interposed between said mounting surface and the electronic component, also
The circuit module, wherein the second resin layer covers at least the upper surface of the first resin layer and the outer surface of the electronic component . The first resin layer is composed of the first resin having the first viscosity at the time of filling, and the second resin layer is composed of the second resin having the second viscosity that is higher than the first viscosity at the time of filling. The circuit module according to claim 1 . A first step of preparing an assembly circuit board in which a plurality of circuit modules are assembled by mounting electronic components on a mounting surface;
The first resin that permeates between the electronic component and the mounting surface is placed on a predetermined number of X-axis cutting lines on the mounting surface and on a predetermined number of Y-axis cutting lines orthogonal to the X-axis cutting line. A second step of filling;
A third step of curing the first resin under predetermined conditions;
Viewed including a fourth step of dividing the collective circuit board to a plurality of circuit modules by dicing the X-axis the cutting line and on the Y-axis cutting line above were filled with a first resin, a
In the second step, the collective circuit board filled with the first resin is put in a mold, and a second resin having a second viscosity higher than the first viscosity of the first resin is put in the mold. A method of manufacturing a circuit module, comprising adding a step of covering the electronic component by filling and molding .

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