JP2900084B2 - Manufacturing method of electronic component mounting board - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of manufacturing an electronic component mounting substrate configured by integrating a base layer with a metal layer, and particularly utilizes laser processing. The present invention relates to an improvement in a method of manufacturing an electronic component mounting substrate in which a predetermined portion of a metal layer is exposed from a base material layer.

(Prior Art) In recent years, electronic components having a higher density cannot constitute various electronic devices as they are, and must be used after being mounted on a substrate. For this purpose, various types of electronic component mounting substrates have been conventionally developed and proposed.

For example, an electronic component mounting substrate of a type in which an electronic component and a terminal such as a lead for connecting the electronic component to the outside are connected on the substrate is a metal layer for forming a conductor layer, a lead or a heat transfer layer. On the other hand, by integrating a substrate layer formed of resin or the like and having excellent insulating properties, and forming a conductor circuit or the like on the surface or inside of the substrate layer, the substrate is configured as a substrate on which electronic components are mounted. It is.

As shown in FIG. 7, the electronic component mounting substrate (13) for mounting the electronic component (20) and the electronic component (20) are generated from the electronic component mounting substrate (13). It is common practice to expose the metal layer (11) from the base material layer (12) for the purpose of forming a heat radiating portion (18) for dissipating the generated heat.

The formation of the electronic component mounting concave portion (13) and the heat radiation portion (18) in which the metal layer (11) is exposed from the base material layer (12) occurs when the electronic component (20) is energized. The heat is directly transmitted to the highly heat-conductive metal layer (11), and this heat is dissipated into the atmosphere from the heat radiating section (18) to enhance the heat dissipation of the electronic component (20). (2
This is because the thickness of the entire electronic component mounting substrate when (0) is mounted is reduced.

There are various methods for manufacturing such a substrate for mounting electronic components. Among them, there is a method for manufacturing a substrate for mounting electronic components proposed by the present applicant in an earlier application (Japanese Patent Application Laid-Open No. 1-113425). Is effective.

According to the claims, the manufacturing method is described as follows: `` by integrating the base layer with the metal layer and exposing a predetermined portion of the metal layer from the base layer through the following steps. A method of manufacturing an electronic component mounting substrate to be configured.

(1) a step of disposing a mask between the metal layer and the base material layer in a portion to be an exposed portion, and then integrating the base material layer with the metal layer; (2) around the mask Irradiating the base material layer on the metal layer with a laser beam from the base layer side to the metal layer side to cut the base layer around the mask; (3) the mask And removing the upper substrate layer together with the mask. "

That is, in this conventional manufacturing method, the metal layer and the base layer are integrated via a mask, then the base layer around the mask is cut by a laser beam, and finally, the base layer on the mask is cut. Is peeled off together with the mask, thereby manufacturing an electronic component mounting substrate in which the metal layer is partially exposed.

(Problems to be Solved by the Invention) By the way, recent electronic component mounting substrates are required to have a high multilayer structure in order to reduce the size and improve the electrical characteristics. As the number of layers increases, the thickness of the electronic component mounting substrate itself naturally becomes larger than in the past. Therefore, in the conventional manufacturing method of cutting the base material layer using the laser light described above, for example, when cutting the base material layer of the multilayered electronic component mounting board using a carbon dioxide laser, In addition, the focal length of carbon dioxide laser light is
When the thickness of the base layer is larger than the focal length of the laser beam, the base layer cannot be completely cut. In other words, when the thickness of the base layer is larger than the focal length of the laser beam, the base layer cannot be completely cut, and the scorching of the base layer by the laser beam, that is, the carbide is left on the metal layer. Will remain.
This carbide has conductivity and causes a disadvantage that the insulation reliability of the electronic component mounting substrate is reduced.
In particular, in the case where the outer shape of the electronic component mounting substrate is processed by a conventional manufacturing method to expose the metal layer serving as the outer lead, the above-mentioned carbide adheres to the outer lead, and the outer material is formed by the carbide. As a result, the insulation resistance between the leads is reduced, and the reliability of the electronic component mounting substrate is reduced.

Therefore, the present invention was devised and an object thereof is to provide a method of manufacturing an electronic component mounting substrate using laser light, wherein the thickness of the base material layer is larger than the focal length of the laser light. Even in such a case, it is an object of the present invention to provide a method capable of easily manufacturing an electronic component mounting substrate having high insulation reliability without generating carbide due to laser light.

(Means for Solving the Problems) Means taken by the present invention to solve the above problems are:
The following description is given with reference numerals used in the examples. “The base layer (12) is integrated with the metal layer (11),
A method for manufacturing an electronic component mounting board (10), comprising exposing a predetermined portion of the metal layer (11) from the base layer (12) through the following steps.

(B) Metal layer (11) to be exposed (11A)
After placing the mask (16) between the substrate and the base layer (12),
A step of integrating the base layer (12) with the metal layer (11); (b) a metal layer (1) located around the mask (16);
1) Counterbore processing is applied to the base material layer (12)
(C) irradiating a laser beam to the concave portion (12C) from the base material layer (12) side to the metal layer (11) side to form a base material around the mask (16). (D) a step of separating the substrate layer (12) on the mask (16) together with the mask (16).

That is, in the method of the present invention, as shown in FIG. 6 (a), the integration of the metal layer (11) and the base material layer (12) in the portion to be the exposed portion (11A) is prevented. For this purpose, a mask (16) is arranged between them, and then the other part of the metal layer (11) and the base material layer (12) are integrated.

The mask (16) is subjected to a shock such as heat and pressure in a series of processes for manufacturing the electronic component mounting substrate (10), such as a process for integrating the metal layer (11) and the base material layer (12). Any material that can be finally peeled off from the metal layer (11) by any method without being deformed even if added may be used, and examples thereof include a resin film having relatively high heat resistance and a metal foil.

In addition, integrating the metal layer (11) and the base material layer (12) can be achieved by applying an appropriate temperature and time while keeping the thermosetting resin before being completely cured in close contact with the metal layer (11). Metal layer (1
This is performed by bonding 1) to the base material layer (12). This integration method includes a prepreg (12
b) Laminating the prepreg (12b) as a base layer (12) by thermocompression bonding with a press, etc., a semi-cured state between the metal layer (11) and the base layer (12) A method for forming a base layer (12) by placing an adhesive sheet (12a) and thermocompression bonding with a press or the like, injecting a thermosetting resin into a mold in which a metal layer (11) is inserted. A so-called injection molding method in which this is heat-cured to form a base material layer (12) can be used.

Next, as shown in FIG. 6 (b), the metal layer (12) positioned on the outer periphery of the mask (16) from the outside of the base material layer (12) to the base material layer (12) as described above. 11) Upper substrate layer (12)
Counterbore processing is performed on the recesses (12
Form C). The depth of the recess (12C) depends on the substrate layer (1
It is necessary to make the remaining thickness of 2) smaller than the focal length of the laser beam. For example, when a carbon dioxide laser is used as the laser beam and the focal length is 1.0 mm, the base layer ( It is necessary to form a recess (12C) having a depth such that the remaining thickness of 12) is 1.0 mm or less. As a means for forming the concave portion (12c), not only a router but also other known methods may be used.

Next, as shown in FIG. 6 (c), a laser beam is irradiated from the side of the base material layer (12) to the side of the metal layer (11) to the recess (12C) of the base material layer (12). You do it.

The laser beam used here is required to cut the base layer (12) well and not to damage the metal layer (11). Is desirable. If a carbon dioxide laser having an oscillation wavelength of 10.6 μm is used, the substrate layer (12) can be cut without damaging the metal layer (11) at all.

As described above, by cutting the base material layer (12) on the metal layer (11) located in the concave portion (12C) by the laser beam, the mask (16) is cut as shown in FIG. A groove is formed in the outer periphery of the substrate to reliably separate the base material layer (12) on the mask (16) from the other base material layer (12).

If such a groove located on the outer periphery on the mask (16) is formed, the base material layer (12) located on the mask (16) becomes
The mask (16) is completely separated from the other base material layer (12), and the mask (16) is not bonded to the metal layer (11) as described above. It is becoming.

Finally, if the base material layer (12) is peeled off from the metal layer (11) together with the mask (16), as shown in FIG. 6 (d), an electronic component mounting part having an exposed metal part (11A) is provided. Substrate (1
0) is formed.

(Operation of the Invention) When the metal exposed portion (11A) of the electronic component mounting board (10) is formed by such a method, the following operation is obtained.

In a portion to be the metal exposed portion (11A), the integration of the base material layer (12) and the metal layer (11) is prevented by the mask (16). That is, for example, even if an adhesive sheet (12a) that adheres to the base material layer (12) and the metal layer (11) has high resin flowability during thermocompression bonding, the mask (16) intervenes. Since it is possible to prevent resin from flowing out of the adhesive sheet (12a) on the surface of the exposed metal part (11A), an adhesive sheet (12a) having excellent properties such as heat resistance, moisture resistance and chemical resistance can be adopted. .

In particular, when a carbon dioxide laser having an oscillation wavelength of 10.6 μm is employed, a laser beam having a high reflectance with respect to a metal can be obtained, and good cutting of resin, glass cloth, and the like can be performed. Therefore, when the concave portion (12C) is irradiated with the laser beam, only the base layer (12) is selectively cut without damaging the metal layer (11). Therefore,
Even when the remaining thickness of the base material layer (12) in the recess (12C) fluctuates slightly, cutting by laser light is always stopped at the surface of the metal layer. It is done exactly.

Further, the processing by the laser beam may be performed on the concave portion (12c) of the base layer (12) on the metal layer (11) located on the outer periphery of the mask (16). Since no operation is required on the layer (12), this processing operation is completed in a very short time.

Further, since the processing by the laser beam is a non-contact processing, the damage of the tool in the processing operation can be completely ignored, so that stable processing can be performed.

Next, the concave part (12C) provided in the base material layer (12), which is the most important part of the present invention, will be described. This recess (1
2C) is formed in order to prevent the laser light from being defocused when the base material layer (12) is cut by irradiation with laser light, and to prevent the generation of carbide due to scorching of the base material layer (12). The substrate layer (1
This is for reducing the substantial thickness of 2). Therefore, by forming the concave portion (12C) in advance, the thickness of the base material layer (12) to be cut is made smaller than the focal length of the laser light, and the carbide of the base material layer (12) by the laser light is reduced. This prevents carbides from adhering to the metal layer (11). Therefore, by adjusting the depth of the concave portion (12C), the substrate layer (12) can be cut without generating carbides regardless of the thickness of the substrate layer (12). .

Example Next, a manufacturing method according to the present invention will be described in detail with reference to an example shown in the drawings.

Example 1 FIGS. 1, 2 and 3 show (a) to (d)
Example 1 of the present invention is shown.

FIGS. 1 and 2 show a case in which an internal connection portion (11C) is integrally formed inside a plurality of outer leads (17a), and a base material layer (10) is formed on both sides of the internal connection portion (11C). By providing 12) integrally, each outer lead (17a) protrudes from the base material layer (12), and the conductor circuit (14) and the outer lead (17a) formed on at least one of the base materials are provided. Is an electronic component mounting board (10) that is electrically connected.

The electronic component mounting board (10) provides electrical connection between the electronic component (20) and the outer leads (17a) by the base layer (1).
2) This is a type that is carried out through the upper conductor circuit (14). In particular, as the metal layer (11), the outer lead (17a) and the internal connection part (11C) are integrally formed. I have. Therefore, in the electronic component mounting board (10), the internal connection portion (11C) constituting the metal layer (11) is formed.
The base layers (12) are integrally provided on both sides of the base material, and the outer leads (17a) protrude outward from the base layers (12). And this electronic component mounting board (10)
Means that the conductor circuit (14) on the base material layer (12) and the outer lead (17a) are electrically connected to each other by the through hole (15) provided through the internal connection portion (11C). It is a feature.

The method of manufacturing the electronic component mounting board (10) will be described below with reference to FIG.

First, a mask is formed so as to cover both surfaces of a portion to be an outer lead (17a) of a lead frame (17) formed by etching a lead frame material (this corresponds to the metal layer (11)). 16) is placed, and prepreg and copper foil are layered on the outside,
These are thermocompression-bonded by a press to be laminated and integrated. As a result, as shown in FIG. 3 (a), the lamination and integration with the base material layer (12) is prevented by the mask (16) in the portion to become the outer lead (17a), A substrate having a shape in which (17) is embedded in the base material layer (12) is formed.

In the first embodiment, the lead frame material has a thickness of 0.25 mm.
A so-called glass triazine prepreg, which was made by impregnating a glass cloth with a bismaleimide triazine resin into a semi-cured state, was used as a prepreg using a copper alloy plate of mm. As the mask (16), a polyphenylene sulfide film having a thickness of 50 μm, so-called PPS, was used.

Next, a through hole (15) for electrically connecting the conductor circuit (14) formed on the surface of the base material layer (12) and the outer lead (17a) is formed by drilling, and the inner wall is formed. Is plated with copper.

Thereafter, when a conductive circuit (14) is formed on the surface of the base material layer (12) by etching, a substrate as shown in FIG. 3 (b) is formed.

Next, both sides of the base layer (12) on the lead frame (17) (metal layer (11)) located on the outer periphery of the mask (16) are subjected to counterboring by a router to form a recess (12c). For example, a substrate as shown in FIG. 3C is formed.

Next, by cutting the base layer (12) on the lead frame (17) (metal layer (11)) located in the concave portion (12c) using a carbon dioxide laser, the outer periphery of the mask (16) is cut off. A groove for surely separating the base material layer (12) on the mask (16) from the other base material layer (12) is formed. Then, since the mask (16) and the outer lead (17a) are not bonded, the mask (16) and the base material layer (12) on the outer lead (17a) are completely separated from other parts. Become.

By performing the same laser processing from the back surface, a substrate as shown in FIG. 3D is formed.

Finally, if the mask (16) and the base material layer (12) on the outer leads (17a) are peeled off, the electronic component mounting substrate (10) as shown in FIGS. 1 and 2 is formed. It is.

The electronic component mounting substrate (1
In (0), the outer leads (1
Since the 7a) is not damaged, the performance of the outer lead (17a) relating to physical strength such as bending strength and pull-out strength does not deteriorate.

In addition, the insulation resistance between the outer leads (17a) of the electronic component mounting board (10) manufactured by this method can be obtained by cutting the base layer (12) only by laser light without forming a recess (12c) in advance. One order of improvement was confirmed in comparison with the above.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. The electronic component mounting board (10) shown in FIG. 4 has an electronic component mounting recess (1) for mounting the electronic component (20).
3) and a heat radiating portion (18) for dissipating heat generated from the electronic component (20) into the atmosphere. A method of manufacturing the heat radiating portion (18) will be described below with reference to FIG.

First, a mask (16) is arranged on a portion to be a metal exposed portion (11A) of an aluminum plate (11B) having a thickness of 1.0 mm, and an adhesive sheet (12a) and a base material layer (12) are stacked outside the mask (16). The aluminum plate (11B) and the base material layer (1
2) are laminated and integrated to form a substrate as shown in FIG. 5 (a).

Here, a 25 μm-thick aluminum foil was used as the mask (16), and a semi-cured film mainly composed of epoxy resin was used as the adhesive sheet (12a). Further, as the base layer (12), one obtained by completely curing a glass epoxy prepreg was used.

Next, both sides of the base material layer (12) on the metal layer (11) located on the outer periphery of the mask (16) are counterbored by a router to form recesses (12c). (B)
A substrate as shown in FIG.

Next, using a carbon dioxide gas laser, the substrate layer (12) on the metal layer (11) located on the outer periphery of the concave portion (12c) is cut to form a substrate as shown in FIG. 5 (c). Is done.

Finally, if the mask (16) and the base material layer (12) on the exposed metal part (11A) are peeled off, as shown in FIG. An electronic component mounting substrate (10) having a concave portion and a heat radiating portion is formed.

Needless to say, the heat radiating portions can be formed on both surfaces of the electronic component mounting substrate (10), and higher heat radiating properties can be obtained in that case.

(Effects of the Invention) As described in detail above, the feature of the present invention is that, as exemplified in the above-described embodiment, “the base layer is integrated with the metal layer, and the predetermined metal layer is formed from the base layer. A method for manufacturing an electronic component mounting substrate, comprising exposing a portion through the following steps.

(A) a step of disposing a mask between the metal layer and the substrate layer in a portion to be an exposed portion, and then integrating the substrate layer with the metal layer; Forming a recess by performing a counterboring process on the base material layer on the metal layer positioned at (c); irradiating the recess with a laser beam from the base material layer side to the metal layer side; (D) a step of separating the base material layer on the mask together with the mask.

Therefore, according to the present invention, even if the cutting process by the laser beam is partial, the formation of the exposed metal portion on the electronic component mounting substrate can be performed reliably and in a short time over a relatively large area without damaging the metal layer. In addition to this, a highly reliable board for mounting electronic components can be easily manufactured.

That is, according to the manufacturing method of the present invention, not only can the metal exposed portion forming the electronic component mounting substrate be formed reliably and in a short time, but also non-contact processing by laser light. In addition, tool damage in the machining operation can be completely ignored.

In addition, since the mask is arranged on the portion to be the metal exposed portion, when the metal layer and the base layer are integrated, the resin does not adhere to the surface of the portion to be the metal exposed portion,
For example, an adhesive sheet having relatively high flowability during thermocompression bonding can be employed.

Therefore, an adhesive sheet having high performance such as heat resistance, chemical resistance, and moisture resistance can be used, and as a result, a highly reliable electronic component mounting substrate can be obtained.

In addition, the laser light characteristic of having a very high cutting ability for resin compared to metal, even if the substrate layer is completely cut, the metal layer will not be damaged, so the cutting depth The control can be performed reliably, and the performance related to the physical strength of the metal layer does not deteriorate.

In addition, the concave portion is formed in advance before cutting the base material layer with the laser light, and the concave portion is cut with the laser light. Even if it is larger, the generation of carbides due to scorching of the base material layer can be prevented, so that a highly reliable board for mounting electronic components can be obtained.

[Brief description of the drawings]

FIG. 1 is a partially enlarged plan view of an electronic component mounting substrate formed by the manufacturing method according to the present invention, and FIG.
3 (a) to 3 (d) are partially enlarged sectional views showing the process of manufacturing the electronic component mounting board shown in FIGS. 1 and 2, respectively. FIG. 4 is a perspective view of another electronic component mounting substrate formed by the manufacturing method according to the present invention, and each of FIGS.
6A to 6D are partial enlarged cross-sectional views showing the process of manufacturing the electronic component mounting board shown in the figure, and each of FIGS. 6A to 6D shows another electronic component mounting substrate formed by the manufacturing method according to the present invention. FIG. 7 is a partially enlarged cross-sectional view showing the process of manufacturing the substrate, and FIG. 7 is a cross-sectional view showing an example of an electronic component mounting substrate. DESCRIPTION OF SYMBOLS 10: electronic component mounting board, 11: metal layer, 11A: exposed metal part, 11C: internal connection part, 12: base material layer, 12a: adhesive sheet,
12b: prepreg, 12c: recess, 13: recess for mounting electronic components, 14: conductor circuit, 15: through hole, 16: mask, 17
… Lead frame, 17a… outer lead, 18… radiator, 20… electronic parts.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 23/12-23/14 H01L 23/50

Claims (1)

(57) [Claims] An electronic component mounting substrate comprising a base layer integrated with a metal layer and a predetermined portion of the metal layer exposed from the base layer through the following steps. Production method. (A) a step of disposing a mask between the metal layer and the substrate layer in a portion to be an exposed portion, and then integrating the substrate layer with the metal layer; Forming a recess by performing a counterboring process on the base material layer on the metal layer positioned at (c); irradiating the recess with a laser beam from the base material layer side to the metal layer side; (D) peeling the substrate layer on the mask together with the mask.