JP3574026B2 - Circuit device and method of manufacturing the same - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a circuit device and a method for manufacturing the same, and more particularly to a thin circuit device that does not require a support substrate and a method for manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a circuit device set in an electronic device is used for a mobile phone, a portable computer, and the like, and therefore, a reduction in size, thickness, and weight is required.
[0003]
For example, taking a semiconductor device as an example of a circuit device, a general semiconductor device is a packaged semiconductor device sealed with a conventional transfer mold. This semiconductor device is mounted on a printed circuit board PS as shown in FIG.
[0004]
In this package type semiconductor device, the periphery of the semiconductor chip 2 is covered with a resin layer 3, and lead terminals 4 for external connection are led out from the side of the resin layer 3.
[0005]
However, in this package type semiconductor device 1, the lead terminals 4 are protruded from the resin layer 3, so that the overall size is large, and the size, thickness, and weight are not satisfied.
[0006]
For this reason, companies have competed to develop various structures in order to realize miniaturization, thinning and weight reduction, and recently called a CSP (chip size package), a wafer scale CSP equivalent to the chip size, or chip size A CSP with a size slightly larger than that has been developed.
[0007]
FIG. 24 shows a CSP 6 that employs a glass epoxy substrate 5 as a support substrate and is slightly larger than the chip size. Here, description will be made assuming that the transistor chip T is mounted on the glass epoxy substrate 5.
[0008]
A first electrode 7, a second electrode 8, and a die pad 9 are formed on the front surface of the glass epoxy substrate 5, and a first back electrode 10 and a second back electrode 11 are formed on the back surface. The first electrode 7 and the first back electrode 10 are electrically connected to each other, and the second electrode 8 and the second back electrode 11 are electrically connected to each other through the through hole TH. The bare transistor chip T is fixed to the die pad 9, the emitter electrode of the transistor is connected to the first electrode 7 via a thin metal wire 12, and the base electrode of the transistor and the second electrode 8 are connected to the thin metal wire 12. Connected through. Further, a resin layer 13 is provided on the glass epoxy substrate 5 so as to cover the transistor chip T.
[0009]
Although the CSP 6 employs the glass epoxy substrate 5, unlike the wafer scale CSP, the extending structure from the chip T to the back surface electrodes 10 and 11 for external connection is simple and has an advantage that it can be manufactured at low cost.
[0010]
The CSP 6 is mounted on a printed circuit board PS as shown in FIG. The printed circuit board PS is provided with electrodes and wiring constituting an electric circuit, and the CSP 6, the package type semiconductor device 1, the chip resistor CR or the chip capacitor CC and the like are electrically connected and fixed.
[0011]
The circuit formed by the printed circuit board is mounted in various sets.
[0012]
Next, a method of manufacturing the CSP will be described with reference to FIGS. In FIG. 26, a flowchart entitled “Galaeppo / flexible substrate in the center” is referred to.
[0013]
First, a glass epoxy substrate 5 is prepared as a base material (support substrate), and Cu foils 20 and 21 are pressure-bonded to both surfaces thereof via an insulating adhesive. (See FIG. 25A above)
Subsequently, Cu foils 20 and 21 corresponding to the first electrode 7, the second electrode 8, the die pad 9, the first back surface electrode 10 and the second back surface electrode 11 are coated with an etching-resistant resist 22, The foils 20 and 21 are patterned. The patterning may be performed separately on the front and back (see FIG. 25B).
Subsequently, a hole for the through hole TH is formed in the glass epoxy substrate by using a drill or a laser, and the hole is plated to form the through hole TH. The first electrode 7 and the first back electrode 10 and the second electrode 8 and the second back electrode 10 are electrically connected by the through hole TH. (See FIG. 25C above)
Although not shown in the drawings, the first electrode 7 and the second electrode 8 serving as bonding posts are plated with Ni, and the die pads 9 serving as die bonding posts are plated with Au, and the transistor chip T is die-bonded. I do.
[0014]
Finally, the emitter electrode of the transistor chip T and the first electrode 7, and the base electrode of the transistor chip T and the second electrode 8 are connected via a thin metal wire 12 and covered with a resin layer 13. (See FIG. 25D above)
Then, if necessary, the wafer is diced and separated as individual electric elements. In FIG. 25, only one transistor chip T is provided on the glass epoxy substrate 5, but in reality, many transistor chips T are provided in a matrix. Therefore, they are finally separated by a dicing device.
[0015]
By the above manufacturing method, a CSP type electric element using the support substrate 5 is completed. This manufacturing method is the same even when a flexible sheet is used as the support substrate.
[0016]
On the other hand, a manufacturing method using a ceramic substrate is shown in the flow on the left side of FIG. After a ceramic substrate as a support substrate is prepared, through holes are formed, and thereafter, front and rear electrodes are printed and sintered using a conductive paste. After that, until the resin layer of the previous manufacturing method is covered, the manufacturing method is the same as that of FIG. There is a problem that can not be molded. Therefore, after potting and hardening the sealing resin, polishing for flattening the sealing resin is performed, and finally, individual separation is performed using a dicing apparatus.
[0017]
[Problems to be solved by the invention]
In FIG. 24, the transistor chip T, the connection means 7 to 12 and the resin layer 13 are necessary components for electrical connection to the outside and protection of the transistor. It has been difficult to provide an electric circuit element that realizes reduction in thickness, thickness, and weight.
[0018]
Further, the glass epoxy substrate 5 serving as a support substrate is not necessary as described above. However, due to the manufacturing method, the glass epoxy substrate 5 was employed as a support substrate for bonding the electrodes, and the glass epoxy substrate 5 could not be eliminated.
[0019]
Therefore, the use of the glass epoxy substrate 5 increases the cost, and further, the glass epoxy substrate 5 is thick, so that the circuit element becomes thick, and there is a limit in reducing the size, thickness, and weight.
[0020]
Further, a through-hole forming step for connecting electrodes on both surfaces is indispensable for a glass epoxy substrate or a ceramic substrate, and there is a problem that the manufacturing process becomes long.
[0021]
[Means for Solving the Problems]
The present invention has been made in view of the above-described many problems, and firstly, a plurality of electrically separated conductive paths, a desired circuit element fixed on the conductive path, and a method of covering the circuit element. And an insulating resin that integrally supports the conductive path, and a side surface of the conductive path is curved to be fitted with the insulating resin, thereby minimizing constituent elements and solving the conventional problem. Further, the conductive path can be realized in which the side surface of the conductive path is curved to prevent the conductive path from coming off from the insulating resin.
[0022]
Second, a plurality of conductive paths electrically separated by the separation groove, a desired circuit element fixed on the conductive path, and the separation groove covering the circuit element and filling the separation groove between the conductive paths. An insulating resin that integrally supports the plurality of conductive paths by bending the side surface of the conductive path and fitting the insulating path with the insulating resin. It is to support and solve the conventional problem.
[0023]
Third, a plurality of conductive paths electrically separated by the separation groove, a desired circuit element fixed on the conductive path, and the separation groove covering the circuit element and filling the separation groove between the conductive paths. An insulating resin that exposes the back surface of the conductive path and integrally supports the conductive path, and that the side surface of the conductive path is curved and fitted with the insulating resin, so that the back surface of the conductive path is connected to the outside. This eliminates the need for a through-hole and solves the conventional problem.
[0024]
Fourthly, a step of preparing a conductive foil, forming a conductive groove having a side surface curved by forming a separation groove shallower than the thickness of the conductive foil in the conductive foil except for at least a region serving as a conductive path,
Fixing a circuit element on the desired conductive path;
A step of covering the circuit element, molding with an insulating resin so as to fill the separation groove, and fitting the conductive path and the insulating resin;
Removing the conductive foil in the thickness portion where the separation groove is not provided, the conductive foil forming the conductive path is a starting material, and the conductive foil is formed until the insulating resin is molded. Having a support function, the insulating resin has a support function after molding, so that a support substrate can be made unnecessary, and the conventional problem can be solved. Further, when forming the separation groove, the side surface of the conductive path has a curved structure, and this structure has an anchor effect.
[0025]
Fifthly, a step of preparing a conductive foil, forming a conductive groove having a side surface curved by forming a separation groove shallower than the thickness of the conductive foil in the conductive foil except for at least a region serving as a conductive path,
Fixing a circuit element on the desired conductive path;
Forming a connection means for electrically connecting an electrode of the circuit element and a desired conductive path; covering the circuit element; molding the insulating element so as to fill the separation groove; Fitting a road and the insulating resin;
Removing the conductive foil in a thickness portion where the separation groove is not provided,
By providing a method of manufacturing a circuit device including a step of cutting the insulating resin and separating the circuit device into individual circuit devices, a large number of circuit devices can be mass-produced, and the conventional problem can be solved.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
First Embodiment for Describing Circuit Device First, the structure of the circuit device of the present invention will be described with reference to FIG.
[0027]
FIG. 1 shows a circuit device having a conductive path 51 embedded in an insulating resin 50, a circuit element 52 is fixed on the conductive path 51, and the conductive path 51 is supported by the insulating resin 50. 53 is shown. Moreover, the side surface of the conductive path 51 has a curved structure 59.
[0028]
This structure is composed of three materials: circuit elements 52A and 52B, a plurality of conductive paths 51A, 51B and 51C, and an insulating resin 50 embedded in the conductive paths 51A, 51B and 51C. A separation groove 54 filled with the insulating resin 50 is provided. The conductive path 51 of the curved structure 59 is supported by the insulating resin 50.
[0029]
As the insulating resin, a thermosetting resin such as an epoxy resin, or a thermoplastic resin such as a polyimide resin or polyphenylene sulfide can be used. As the insulating resin, any resin can be adopted as long as the resin can be hardened using a mold, or can be coated by dipping or coating. Further, as the conductive path 51, a conductive foil mainly composed of Cu, a conductive foil mainly composed of Al, a conductive foil made of an alloy such as Fe-Ni, or the like can be used. Of course, other conductive materials are possible, and in particular, a conductive material that can be etched and a conductive material that evaporates by laser are preferable.
[0030]
In the present invention, the side surface of the conductive path 51 is formed into a curved structure 59 by performing non-anisotropic etching, particularly by employing dry etching or wet etching, thereby generating an anchor effect. As a result, a structure in which the conductive path 51 does not come off from the insulating resin 50 is realized.
[0031]
The connection means of the circuit element 52 includes a thin metal wire 55A, a conductive ball made of a brazing material, a flat conductive ball, a brazing material 55B such as a solder, a conductive paste 55C such as an Ag paste, a conductive film or an anisotropic conductive resin. It is. These connection means are selected depending on the type of the circuit element 52 and the mounting form of the circuit element 52. For example, in the case of a bare semiconductor element, a thin metal wire is selected for the connection between the electrode on the surface and the conductive path 51, and in the case of a CSP, a solder ball or a solder bump is selected. As the chip resistor and the chip capacitor, the solder 55B is selected. There is no problem even if a packaged circuit element, for example, a BGA or the like is mounted on the conductive path 51, and when this is adopted, solder is selected as the connection means.
[0032]
For electrical connection between the circuit element and the conductive path 51A, an insulating adhesive is selected if electrical connection is not required, and a conductive coating is employed if electrical connection is required. Here, at least one conductive film is sufficient.
[0033]
The material considered as the conductive film is Ag, Au, Pt, Pd, or the like, and is coated by deposition under low or high vacuum such as evaporation, sputtering, or CVD, plating, or sintering.
[0034]
For example, Ag adheres to Au and also adheres to brazing material. Therefore, if the Au film is coated on the back surface of the chip, the chip can be thermocompression-bonded by directly covering the conductive path 51A with the Ag film, Au film, or solder film, and the chip can be fixed via a brazing material such as solder. . Here, the conductive film may be formed on the uppermost layer of the conductive film laminated in a plurality of layers. For example, on the conductive path 51A of Cu, two layers of a Ni film and an Au film are sequentially applied, an Ni film, a Cu film, three layers of a solder film are sequentially applied, an Ag film, One in which two layers of the Ni film are sequentially coated can be formed. Although there are many other types and laminated structures of these conductive films, they are omitted here.
[0035]
In the present circuit device, since the conductive path 51 is supported by the insulating resin 50 as the sealing resin, a support substrate is not required, and the circuit apparatus includes the conductive path 51, the circuit element 52, and the insulating resin 50. This configuration is a feature of the present invention. As described in the section of the related art, the conductive path of the conventional circuit device is supported by a support substrate or supported by a lead frame, and therefore, a configuration that may not be necessary is added. However, this circuit device has a feature that it is thin and inexpensive because it is composed of the minimum necessary components and does not require a support substrate.
[0036]
In addition to the above-described configuration, there is provided an insulating resin 50 that covers the circuit element 52 and fills the separation groove 54 between the conductive paths 52 and integrally supports the same.
[0037]
A separation groove 54 is formed between the conductive paths 51 of the curved structure 59, and by filling the insulating resin 50 into the separation groove 54, the conductive paths 51 can be prevented from coming off and at the same time, they have the advantage of being insulated from each other.
[0038]
In addition, there is an insulating resin 50 which covers the circuit element 52 and is filled in the separation groove 54 between the conductive paths 51 to expose only the back surface of the conductive path 51 and integrally support the same.
[0039]
Exposing the back surface of the conductive path is one of the features of the present invention. The back surface of the conductive path can be used for connection to the outside, and has a feature that the through hole TH of the conventional structure as shown in FIG. 24 can be omitted.
[0040]
Moreover, when the circuit element is directly fixed via a conductive film such as brazing material, Au, Ag, or the like, the back surface of the conductive path 51 is exposed, so that heat generated from the circuit element 52A is mounted via the conductive path 51A. Can be transmitted to the substrate. In particular, it is effective for a semiconductor chip capable of improving characteristics such as an increase in drive current due to heat radiation.
[0041]
In addition, the circuit device has a structure in which the surface of the separation groove 54 and the surface of the conductive path 51 substantially match. This structure is a feature of the present invention, and has a feature that the circuit device 53 can be horizontally moved as it is because no step is provided between the back electrodes 10 and 11 shown in FIG.
Second Embodiment for Explaining Circuit Device Next, a circuit device 56 shown in FIG. 7 will be described.
[0042]
This structure is substantially the same as the structure of FIG. 1 except that a conductive film 57 is formed on the surface of the conductive path 51. Therefore, the conductive film 57 will be described.
[0043]
The first feature is that a conductive coating 57 is provided to prevent warpage of the conductive path and the circuit device.
[0044]
Generally, due to the difference in thermal expansion coefficient between the insulating resin and the conductive path material (hereinafter, referred to as a first material), the circuit device itself warps, and the conductive path is bent or peeled off. Further, since the thermal conductivity of the conductive path 51 is superior to the thermal conductivity of the insulating resin, the conductive path 51 expands by increasing the temperature first. Therefore, by covering the second material with a smaller coefficient of thermal expansion than the first material, it is possible to prevent the conductive path from being warped or peeled off and the circuit device from being warped. In particular, when Cu is used as the first material, Au, Ni, Pt, or the like is preferable as the second material. The expansion coefficient of Cu is 16.7 × 10 −6 (10 minus the sixth power), Au is 14 × 10 −6, Ni is 12.8 × 10 −6, and Pt is 8.9 × 10 6. −6.
[0045]
The second feature is that the second material has an anchor effect. Since the eaves 58 are formed of the second material, and the eaves 58 attached to the conductive paths 51 are embedded in the insulating resin 50, an anchor effect is generated and a structure in which the conductive paths 51 can be prevented from coming off is obtained. .
[0046]
In the present invention, both the curved structure 59 and the eaves 58 generate a double anchor effect to prevent the conductive path 51 from coming off.
[0047]
The circuit device in which the transistor chip 52A and the passive element 52B are mounted has been described as the circuit device. However, the present invention relates to a circuit device in which one semiconductor chip is sealed as shown in FIG. As shown in FIG. 21, a circuit device 81 in which a face-down type element 80 such as a CSP is mounted, or a circuit device 83 in which a passive element 82 such as a chip resistor or a chip capacitor is sealed as shown in FIG. Further, a thin metal wire may be connected between the two conductive paths and sealed. This can be used as a fuse.
First Embodiment Explaining Method for Manufacturing Circuit Device Next, a method for manufacturing a circuit device 53 will be described with reference to FIGS. 2 to 6 and FIG.
[0048]
First, as shown in FIG. 2, a sheet-shaped conductive foil 60 is prepared. The material of the conductive foil 60 is selected in consideration of the adhesiveness, bonding property, and plating property of the brazing material. As the material, a conductive foil mainly containing Cu, a conductive foil mainly containing Al, or Fe -A conductive foil made of an alloy such as Ni is employed.
[0049]
The thickness of the conductive foil is preferably about 10 μm to 300 μm in consideration of the later etching, and here, a copper foil of 70 μm (2 oz) was employed. However, it is basically good to be 300 μm or more and 10 μm or less. As will be described later, it is only necessary that the separation groove 61 shallower than the thickness of the conductive foil 60 can be formed.
[0050]
In addition, the sheet-shaped conductive foil 60 is prepared by being wound into a roll with a predetermined width, and may be conveyed to each step described later, or a conductive foil cut to a predetermined size is prepared, It may be transported to each step described later.
[0051]
Subsequently, there is a step of removing the conductive foil 60 excluding at least a region to be the conductive path 51 so as to be thinner than the thickness of the conductive foil 60. Then, there is a step of coating the insulating resin 50 on the separation groove 61 and the conductive foil 60 formed in this removing step.
[0052]
First, as shown in FIG. 3, a photoresist PR (etching resistant mask) is formed on the Cu foil 60, and the photoresist PR is patterned so that the conductive foil 60 excluding a region serving as the conductive path 51 is exposed. Then, as shown in FIG. 4A, etching is performed via the photoresist PR.
[0053]
In the present manufacturing method, non-anisotropic etching is performed by wet etching or dry etching, and the side surfaces thereof are rough and curved. Note that the depth of the separation groove 61 formed by etching is about 50 μm.
[0054]
In the case of wet etching, ferric chloride or cupric chloride is used as an etchant, and the conductive foil is dipped in the etchant or the etchant is showered.
[0055]
In particular, as shown in FIG. 4B, the etching in the horizontal direction is difficult to proceed immediately below the photoresist PR serving as an etching mask, and the portion deeper than that is etched in the horizontal direction. As shown in the figure, if the opening diameter of the opening corresponding to the position becomes smaller from a certain position of the side surface of the separation groove 61 upward, the structure becomes an inversely tapered structure and has a structure having an anchor structure. In addition, by employing a shower ring, etching proceeds in the depth direction and etching in the horizontal direction is suppressed, so that this anchor structure appears remarkably.
[0056]
In the case of dry etching, anisotropic and non-anisotropic etching is possible. At present, it is said that it is impossible to remove Cu by reactive ion etching, but it can be removed by sputtering. In addition, anisotropic and non-anisotropic etching can be performed depending on sputtering conditions.
[0057]
In FIG. 3, a conductive film having corrosion resistance to an etching solution may be selectively coated instead of the photoresist. When the conductive film is selectively applied to a portion to be a conductive path, the conductive film serves as an etching protective film, and the separation groove can be etched without employing a resist. Materials that can be considered as the conductive film include Ag, Au, Pt, and Pd. Moreover, these corrosion-resistant conductive films have a feature that they can be used as they are as die pads and bonding pads.
[0058]
For example, the Ag film adheres to Au and also adheres to the brazing material. Therefore, if the Au film is coated on the back surface of the chip, the chip can be thermocompression-bonded to the Ag film on the conductive path 51 as it is, and the chip can be fixed via a brazing material such as solder. Since the Au thin wire can be bonded to the Ag conductive film, wire bonding is also possible. Therefore, there is an advantage that these conductive films can be used as die pads and bonding pads as they are.
[0059]
Subsequently, as shown in FIG. 5, there is a step of electrically connecting and mounting the circuit element 52 to the conductive foil 60 in which the separation groove 61 is formed.
[0060]
The circuit element 52 is a semiconductor element 52A such as a transistor, a diode, or an IC chip, and a passive element 52B such as a chip capacitor or a chip resistor. Although the thickness is increased, a face-down semiconductor element such as CSP or BGA can be mounted.
[0061]
Here, the bare transistor chip 52A is die-bonded to the conductive path 51A, and the emitter electrode and the conductive path 51B, and the base electrode and the conductive path 51B are fixed by ball bonding by thermocompression bonding or web bonding by ultrasonic waves. Connected via Reference numeral 52B denotes a chip capacitor or a passive element, which is fixed with a brazing material such as solder or a conductive paste 55B.
[0062]
Further, as shown in FIG. 6, there is a step of attaching an insulating resin 50 to the conductive foil 60 and the curved separation groove 61. This can be achieved by transfer molding, injection molding, or dipping. As the resin material, a thermosetting resin such as an epoxy resin can be realized by transfer molding, and a thermoplastic resin such as a polyimide resin and polyphenylene sulfide can be realized by injection molding.
[0063]
In the present embodiment, the thickness of the insulating resin coated on the surface of conductive foil 60 is adjusted so as to cover about 100 μm from the top of fine metal wire 55A. This thickness can be increased or reduced in consideration of the strength of the circuit device.
[0064]
The feature of this step is that the conductive foil 60 serving as the conductive path 51 becomes a support substrate until the insulating resin 50 is covered. Conventionally, as shown in FIG. 25, the conductive paths 7 to 11 are formed by using the support substrate 5 which is not originally required. However, in the present invention, the conductive foil 60 serving as the support substrate is required as an electrode material. Material. Therefore, there is a merit that the operation can be performed while omitting the constituent materials as much as possible, and the cost can be reduced.
[0065]
Further, since the separation grooves 61 are formed shallower than the thickness of the conductive foil, the conductive foils 60 are not individually separated as the conductive paths 51. Therefore, it can be handled integrally as the sheet-shaped conductive foil 60, and has a feature that when the insulating resin is molded, the work of transporting to the mold and mounting on the mold becomes extremely easy.
[0066]
Furthermore, since the insulating groove 50 having the curved structure 59 is filled with the insulating resin 50, an anchor effect is generated at this portion, and the insulating resin 50 can be prevented from peeling off. Of the conductive path 51 can be prevented.
[0067]
Subsequently, there is a step of chemically and / or physically removing the back surface of the conductive foil 60 and separating it as the conductive path 51. Here, this removing step is performed by polishing, grinding, etching, laser metal evaporation, or the like.
[0068]
In the experiment, the entire surface was shaved by about 30 μm with a polishing device or a grinding device, and the insulating resin 50 was exposed from the separation groove 61. This exposed surface is indicated by a dotted line in FIG. As a result, the conductive paths 51 having a thickness of about 40 μm are separated. Alternatively, the entire surface of the conductive foil 60 may be wet-etched before the insulating resin 50 is exposed, and thereafter, the entire surface may be ground by a polishing or grinding device to expose the insulating resin 50.
[0069]
As a result, a structure in which the surface of the conductive path 51 is exposed to the insulating resin 50 is obtained. Then, the separation groove 61 is cut off to form the separation groove 54 of FIG. (See Figure 6 above)
Finally, a conductive material such as solder is applied to the exposed conductive path 51 as necessary, thereby completing a circuit device.
[0070]
When a conductive film is applied to the back surface of the conductive path 51, the conductive film may be formed in advance on the back surface of the conductive foil of FIG. In this case, the portion corresponding to the conductive path may be selectively applied. The deposition method is, for example, plating. The conductive film is preferably made of a material having resistance to etching. When this conductive film is employed, it can be separated as the conductive path 51 only by etching without polishing.
[0071]
In this manufacturing method, only the transistor and the chip resistor are mounted on the conductive foil 60. However, these may be arranged in a matrix as one unit, or one of the circuit elements may be set as one unit. They may be arranged in a matrix. In this case, as described later, they are individually separated by a dicing device.
[0072]
By the manufacturing method described above, the conductive path 51 is embedded in the insulating resin 50, and a flat circuit device 56 in which the back surface of the insulating resin 50 and the back surface of the conductive path 51 match can be realized.
[0073]
The feature of this manufacturing method is that the conductive path 51 can be separated using the insulating resin 50 as a support substrate. The insulating resin 50 is a material necessary as a material for embedding the conductive path 51, and does not require an unnecessary support substrate 5 unlike the conventional manufacturing method of FIG. Therefore, it is characterized by being able to be manufactured with a minimum of materials and realizing cost reduction.
[0074]
Note that the thickness of the insulating resin from the surface of the conductive path 51 can be adjusted at the time of attaching the insulating resin in the previous step. Therefore, the thickness of the circuit device 56 has the characteristic that it can be thick or thin, though it depends on the circuit element to be mounted. Here, a mounting substrate is obtained in which a 40 μm conductive path 51 and circuit elements are embedded in a 400 μm thick insulating resin 50. (See Figure 1 above)
Second Embodiment for Demonstrating Method of Manufacturing Circuit Device Next, a method of manufacturing a circuit device 56 having an eave 58 will be described with reference to FIGS. Note that, except that the second material 70 serving as an eaves is adhered, the second embodiment is substantially the same as the first embodiment, and thus detailed description is omitted.
[0075]
First, as shown in FIG. 8, a conductive foil 60 in which a second material 70 having a small etching rate is coated on a conductive foil 60 made of a first material is prepared.
[0076]
For example, when Ni is deposited on a Cu foil, Cu and Ni can be etched at once with ferric chloride, cupric chloride, or the like, and Ni is formed as eaves 58 due to a difference in etching rate. is there. The thick solid line is the conductive film 70 made of Ni, and its thickness is preferably about 1 to 10 μm. Also, the eaves 58 are more likely to be formed as the Ni film thickness is larger.
[0077]
The second material may cover a material which can be selectively etched with the first material. In this case, the eaves 58 can be formed by first patterning a film made of the second material so as to cover the formation region of the conductive path 51 and etching the film made of the first material using this film as a mask. is there. As the second material, Al, Ag, Au or the like can be considered. (See FIG. 8 above)
Subsequently, there is a step of removing the conductive foil 60 excluding at least a region to be the conductive path 51 so as to be thinner than the thickness of the conductive foil 60.
[0078]
A photoresist PR may be formed on the Ni 70, the photoresist PR may be patterned so that the Ni 70 excluding the region serving as the conductive path 51 is exposed, and the photoresist PR may be etched through the photoresist.
[0079]
As described above, when etching is performed by using an etchant of ferric chloride or cupric chloride or the like, since the etching rate of Ni70 is lower than the etching rate of Cu60, the eaves 58 appear as the etching proceeds.
[0080]
The step of mounting the circuit element 52 on the conductive foil 60 in which the separation groove 61 is formed (FIG. 11), the conductive foil 60 and the separation groove 61 are covered with an insulating resin 50, and the back surface of the conductive foil 60 is chemically coated. The step of isolating the conductive path 51 (FIG. 12) and the step of forming a conductive film on the back surface of the conductive path until completion (FIG. 7) are the same as those in the previous manufacturing method, except for physically and / or physically. The description is omitted.
Third Embodiment for explaining a method of manufacturing a circuit device Next, a method of manufacturing a discrete device and an IC device by arranging one kind of circuit elements in a matrix, separating them individually after sealing, and forming the same will be described with reference to FIGS. This will be described with reference to FIG. Since the manufacturing method is almost the same as the first embodiment, the same parts will be described briefly.
[0081]
First, as shown in FIG. 13, a sheet-shaped conductive foil 60 is prepared.
[0082]
In addition, the sheet-shaped conductive foil 60 is prepared by being wound into a roll with a predetermined width, and may be conveyed to each step described later, or a conductive foil cut to a predetermined size is prepared, It may be transported to each step described later.
[0083]
Subsequently, there is a step of removing the conductive foil 60 excluding at least a region to be the conductive path 51 so as to be thinner than the thickness of the conductive foil 60.
[0084]
First, as shown in FIG. 14, a photoresist PR is formed on the Cu foil 60, and the photoresist PR is patterned so that the conductive foil 60 excluding the region serving as the conductive path 51 is exposed. Then, as shown in FIG. 15, etching may be performed via the photoresist PR.
[0085]
The depth of the separation groove 61 formed by etching is, for example, 50 μm, and the side surface thereof is roughened, so that the adhesiveness to the insulating resin 50 is improved.
[0086]
The side wall of the separation groove 61 is curved because it is non-anisotropically etched. For this removing step, wet etching or dry etching can be adopted. The curved structure provides a structure in which an anchor effect is generated. (For details, refer to the first embodiment which describes a method of manufacturing a circuit device.)
In FIG. 14, a conductive film having corrosion resistance to an etchant may be selectively coated instead of the photoresist PR. When the conductive film is selectively applied to a portion to be a conductive path, the conductive film serves as an etching protective film, and the separation groove can be etched without employing a resist.
[0087]
Subsequently, as shown in FIG. 16, there is a step of electrically connecting and mounting the circuit element 52A to the conductive foil 60 in which the separation groove 61 is formed.
[0088]
The circuit element 52A is a transistor, a diode, a semiconductor element such as an IC chip, or a passive element such as a chip capacitor or a chip resistor. Although the thickness is increased, a face-down semiconductor element such as CSP or BGA can be mounted.
[0089]
Here, the bare transistor chip 52A is die-bonded to the conductive path 51A, and the emitter electrode and the conductive path 51B, and the base electrode and the conductive path 51B are connected via a thin metal wire 55A.
[0090]
Further, as shown in FIG. 17, there is a step of attaching an insulating resin 50 to the conductive foil 60 and the separation groove 61. This can be achieved by transfer molding, injection molding, or dipping.
[0091]
In the present embodiment, the thickness of the insulating resin coated on the surface of the conductive foil 60 is adjusted so as to cover about 100 μm from the highest point of the mounted circuit element. This thickness can be increased or reduced in consideration of the strength of the circuit device.
[0092]
The feature of this step is that, when the insulating resin 50 is coated, the conductive foil 60 serving as the conductive path 51 serves as a support substrate. Conventionally, as shown in FIG. 25, the conductive paths 7 to 11 are formed by using the support substrate 5 which is not originally required. However, in the present invention, the conductive foil 60 serving as the support substrate is required as an electrode material. Material. Therefore, there is a merit that the operation can be performed while omitting the constituent materials as much as possible, and the cost can be reduced.
[0093]
Further, since the separation grooves 61 are formed shallower than the thickness of the conductive foil, the conductive foils 60 are not individually separated as the conductive paths 51. Therefore, it can be handled integrally as the sheet-shaped conductive foil 60, and has a feature that when the insulating resin is molded, the work of transporting to the mold and mounting on the mold becomes extremely easy.
[0094]
Subsequently, there is a step of chemically and / or physically removing the back surface of the conductive foil 60 and separating it as the conductive path 51. Here, the removing step is performed by polishing, grinding, etching, laser metal evaporation, or the like.
[0095]
In the experiment, the entire surface was shaved by about 30 μm with a polishing device or a grinding device to expose the insulating resin 50. This exposed surface is indicated by a dotted line in FIG. As a result, the conductive paths 51 having a thickness of about 40 μm are separated. Alternatively, the entire surface of the conductive foil 60 may be wet-etched before the insulating resin 50 is exposed, and thereafter, the entire surface may be ground by a polishing or grinding device to expose the insulating resin 50.
[0096]
As a result, a structure in which the surface of the conductive path 51 is exposed to the insulating resin 50 is obtained.
[0097]
Further, as shown in FIG. 18, a conductive material such as solder is applied to the exposed conductive path 51.
[0098]
Finally, as shown in FIG. 19, there is a step of separating each circuit element to complete a circuit device.
[0099]
The separation line is located at the arrow and can be realized by dicing, cutting, pressing, chocolate break, or the like. When a chocolate break is used, a protrusion may be formed on the mold so that a groove is formed in the separation line when the insulating resin is coated.
[0100]
In particular, dicing is preferred because it is frequently used in a normal method of manufacturing a semiconductor device and can separate very small objects.
[0101]
On the right side of FIG. 26, a flow briefly summarizing the present invention is shown. A circuit device can be realized by nine steps of preparation of Cu foil, plating of Ag or Ni or the like, half etching, die bonding, wire bonding, transfer molding, removal of back foil Cu foil, back surface treatment of conductive paths, and dicing. Moreover, all processes can be performed in-house without supplying a supporting substrate from a manufacturer.
An embodiment for explaining types of circuit devices and methods for mounting them.
[0102]
FIG. 20 shows a circuit device 81 on which a face-down type circuit element 80 is mounted. The circuit element 80 corresponds to a bare semiconductor chip, a CSP or BGA having a sealed surface, or the like. FIG. 21 shows a circuit device 83 on which passive elements 82 such as a chip resistor and a chip resistor are mounted. Since they do not require a supporting substrate, they are thin and are sealed with an insulating resin, so that they have excellent environmental resistance.
[0103]
FIG. 22 illustrates the real layer structure. The circuit devices 53, 81, and 83 of the present invention described above are mounted on conductive paths 85 formed on a mounting substrate 84 such as a printed substrate, a metal substrate, or a ceramic substrate.
[0104]
In particular, since the conductive path 51A to which the back surface of the semiconductor chip 52 is fixed is thermally coupled to the conductive path 85 of the mounting substrate 84, the heat of the circuit device can be radiated through the conductive path 85. . When a metal substrate is used as the mounting substrate 84, the heat dissipation of the metal substrate is also helped, and the temperature of the semiconductor chip 52 can be further reduced. Therefore, the driving capability of the semiconductor chip can be improved.
[0105]
For example, power MOS, IGBT, SIT, transistor for driving a large current, IC (MOS type, BIP type, Bi-CMOS type) memory element for driving a large current are suitable.
[0106]
As the metal substrate, an Al substrate, a Cu substrate, and an Fe substrate are preferable, and an insulating resin and / or an oxide film are formed in consideration of a short circuit with the conductive path 85.
[0107]
【The invention's effect】
As is apparent from the above description, according to the present invention, the circuit device is configured with the minimum necessary amounts of the circuit device, the conductive path, and the insulating resin, and the circuit device has no waste in resources. Therefore, there is no extra component until completion, and a circuit device that can greatly reduce the cost can be realized. Further, by setting the coating thickness of the insulating resin and the thickness of the conductive foil to optimal values, it is possible to realize a very small, thin, and lightweight circuit device.
[0108]
Further, since only the back surface of the conductive path is exposed from the insulating resin, the back surface of the conductive path can be immediately used for connection to the outside, and the back electrode and the through hole of the conventional structure as shown in FIG. 24 can be eliminated. Having.
[0109]
Moreover, when the circuit element is directly fixed via a conductive film such as brazing material, Au, Ag, etc., since the back surface of the conductive path is exposed, heat generated from the circuit element is directly transferred to the mounting board via the conductive path. Can transmit heat. In particular, this heat dissipation makes it possible to mount a power element.
[0110]
In addition, this circuit device has a structure in which the surface of the separation groove and the surface of the conductive path have a flat surface substantially coincident with each other. When the narrow pitch QFP is mounted, the circuit device itself can be moved horizontally without change. Correction of the deviation becomes extremely easy.
[0111]
Further, since the second material is formed on the front side of the conductive path, it is possible to suppress the warpage of the mounting substrate due to the difference in the coefficient of thermal expansion, particularly the warping or peeling of the elongated wiring.
[0112]
Further, the side surface of the conductive path has a curved structure, and further, by forming a coating made of the second material on the surface of the conductive path, an eave attached to the conductive path can be formed. Therefore, an anchor effect can be generated, and the conductive path can be prevented from warping or coming off.
[0113]
In the method for manufacturing a circuit device according to the present invention, the conductive foil itself serving as the material of the conductive path is made to function as a support substrate, and the conductive foil is used until the separation groove is formed or the circuit element is mounted and the insulating resin is attached. When the whole is supported and the conductive foil is separated as each conductive path, an insulating resin is used as a supporting substrate to function. Therefore, the circuit element, the conductive foil, and the insulating resin can be manufactured with the minimum necessary. As described in the conventional example, a support substrate is not required for originally configuring the circuit device, and the cost can be reduced. In addition, there is no need for a support substrate, the conductive paths are embedded in the insulating resin, and the thickness of the insulating resin and the conductive foil can be adjusted, so that an extremely thin circuit device can be formed. There is also. Further, a curved structure can be formed in the step of forming the separation groove, and a structure having an anchor effect can be realized at the same time.
[0114]
Further, as is apparent from FIG. 26, the steps of forming the through holes and the step of printing the conductor (in the case of a ceramic substrate) can be omitted. Having. In addition, no frame mold is required at all, and this is a manufacturing method with a very short delivery time.
[0115]
Since the conductive paths can be handled without being separated individually until the step of removing the thinner than the thickness of the conductive foil (for example, half etching), workability is improved in the subsequent step of coating the insulating resin. Have.
[0116]
Further, since the same surface is formed by the conductive path and the insulating resin, the mounted circuit device can be shifted without hitting the side of the conductive path on the mounting board. In particular, a circuit device mounted with a displacement can be repositioned while being shifted in the horizontal direction. Also, if the brazing material is melted after mounting the circuit device, the misaligned mounted circuit device will try to return to the upper part of the conductive path by the surface tension of the melted brazing material, and can be rearranged by the circuit device itself. It becomes.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a circuit device of the present invention.
FIG. 2 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 3 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 4 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 5 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 6 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 7 is a diagram illustrating a circuit device according to the present invention.
FIG. 8 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 9 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 10 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 11 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 12 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 13 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 14 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 15 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 16 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 17 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 18 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 19 is a diagram illustrating a method for manufacturing a circuit device according to the present invention.
FIG. 20 is a diagram illustrating a circuit device according to the present invention.
FIG. 21 is a diagram illustrating a circuit device of the present invention.
FIG. 22 is a diagram illustrating a method for mounting the circuit device of the present invention.
FIG. 23 is a diagram illustrating a mounting structure of a conventional circuit device.
FIG. 24 is a diagram illustrating a conventional circuit device.
FIG. 25 is a diagram illustrating a conventional method for manufacturing a circuit device.
FIG. 26 is a diagram illustrating a method for manufacturing a circuit device according to the related art and the present invention.
[Explanation of symbols]
Reference Signs List 50 insulating resin 51 conductive path 52 circuit element 53 circuit device 54 separation groove 58 eaves 59 curved structure

Claims (12)

A step of preparing a conductive foil;
  Forming a separation groove deeper than the conductive path to be formed on the surface of the conductive foil to form the conductive path in a convex shape;
  A step of electrically connecting the circuit element and the conductive path by disposing a circuit element face down on the conductive path,
  Forming an insulating resin so as to seal the circuit element and fill the separation groove below the circuit element;
  Removing the conductive foil from the back surface until the conductive paths are separated by a thickness smaller than the depth of the separation groove. 2. The method according to claim 1, wherein the separation groove is formed by wet etching. The removal of the back surface of the conductive foil is performed by wet etching. One A manufacturing method of the circuit device according to the above. The method according to claim 1, wherein the circuit element is an IC chip, a CSP, or a BGA. 2. The method according to claim 1, wherein a side surface of the conductive path is a curved surface. A plurality of units each including the conductive path constituting one circuit device are formed on the conductive foil,
  2. The method for manufacturing a circuit device according to claim 1, wherein after separating the conductive paths, the insulating resin between the units is cut into individual circuit devices. Prepare a conductive foil in which a separation groove deeper than the conductive path to be formed is formed and the conductive path is formed in a convex shape,
  A circuit element is arranged face-down on the conductive path to electrically connect the circuit element and the conductive path,
  Forming an insulating resin so as to seal the circuit element and fill the separation groove below the circuit element;
  A method of manufacturing a circuit device, comprising: removing the conductive foil from the back surface until the conductive paths are separated by a thickness smaller than the depth of the separation groove. 8. The method according to claim 7, wherein the formation of the separation groove is performed by wet etching. 8. The method according to claim 7, wherein the removal of the back surface of the conductive foil is performed by wet etching. The method according to claim 7, wherein the circuit element is an IC chip, a CSP, or a BGA. 8. The method according to claim 7, wherein a side surface of the conductive path is a curved surface.   A plurality of units each including the conductive path constituting one circuit device are formed on the conductive foil,
  The method for manufacturing a circuit device according to claim 7, wherein after separating the conductive paths, the insulating resin between the units is cut into individual circuit devices.

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