JPH04159764A - Manufacture of electronic component mounting board - Google Patents

Abstract

PURPOSE:To form a metal exposed part widely, surely, and in a short time, to eliminate generation of fine dusts and to enhance reliability by integrating a metal layer with a base material layer, and exposing a predetermined part of the metal layer through a specific step. CONSTITUTION:After a mask 16 is disposed between a metal layer 11 of a part to be exposed and a base material layer 12, the layer 12 is integrated with the layer 11. Then, the layer 11 is irradiated with a laser light from the layer 12 side to the layer 12 on the layer 11 disposed on the periphery of the mask 16, and the layer 12 at the periphery of the mask 16 is cut. Then, the layer 12 on the mask 16 is peeled together with the mask 16, and at least the cut port of the layer 12 and the layer 11 near it are polished by jet scrub polishing. Thus, it can be conducted in a relatively wide area surely and in a short time, no fine dust is generated, and reliability is enhanced.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a substrate for mounting electronic components, which is constructed by integrating a base material layer with a metal layer, and in particular, relates to a method for manufacturing a substrate for mounting electronic components, which uses laser processing. The present invention relates to an improvement in a method of manufacturing a substrate for mounting electronic components in which a predetermined portion of a metal layer is exposed from a base material layer.

(Prior Art) Recent high-density electronic components cannot be used as they are to construct various electronic devices, so they must be mounted on a board before use. To this end, various types of electronic component mounting boards have been developed and proposed.

For example, an electronic component mounting board that connects an electronic component and a terminal such as a lead for connecting it to the outside on the board has a metal layer that serves as a conductor layer, lead, or heat transfer layer. On the other hand, it is constructed as a board on which electronic components are mounted by integrating a base material layer made of resin etc. with excellent insulating properties and forming a conductor circuit etc. on the surface or inside of this base material layer. It is.

For this type of electronic component mounting board, the seventh
As shown in the figure, the base material layer ( 1
2) It is common practice to expose the metal layer (11).

The formation of such electronic component mounting recesses (13) and heat dissipation portions (18) in which the metal layer (11) is exposed from the base material layer (12) occurs when the electronic component (20) is energized. By transmitting heat directly to the highly thermally conductive metal layer (11) and further dissipating this heat into the atmosphere from the heat dissipation part (18), it is possible to improve the heat dissipation of the electronic component (20), or to improve the heat dissipation of the electronic component (20). This is for reasons such as reducing the thickness of the entire electronic component mounting board when mounting the electronic component (20).

There are various methods for manufacturing such a substrate for mounting electronic components, and among them, ``manufacturing of a substrate for mounting electronic components'' proposed by the present applicant in a previous application (Japanese Patent Application No. 1-113425). ``Method'' is effective.

From the scope of the claims, this manufacturing method is defined as: [By integrating a base material layer with a metal layer and exposing a predetermined portion of the metal layer from the base material layer through the following steps. A method of manufacturing a board for mounting electronic components comprising:

(1) A step of arranging a mask between the metal layer and the base material layer in a portion that is to become an exposed portion, and then integrating the base material layer with the metal layer; (2) Surroundings of the mask A step of cutting the base material layer around the mask by irradiating a laser beam from the base layer side to the metal layer side with respect to the -3= base material layer located on the metal layer; (3 ) A step of peeling off the second base material layer together with the mask.

In other words, this conventional manufacturing method integrates a metal layer and a base material layer through a mask, then cuts the base material layer around the mask using a laser beam, and finally cuts the base material layer on the mask. By peeling off the mask together with the mask, an electronic component mounting board with a partially exposed metal layer is manufactured.

(Problem to be Solved by the Invention) However, in the conventional manufacturing method, when the base material layer is cut with a laser beam, altered substances due to the heat of the laser light are left on the cut surface of the cut base material layer and There remained the problem that fine dust was generated from the electronic component mounting board, which must be clean, by adhering to the metal layer around the periphery or near the cut edge thereof.

In addition, even when the external shape of a board for mounting electronic components is processed using conventional manufacturing methods to expose the metal layer that will become the outer lead, the above-mentioned degenerate substances will adhere to the outer lead, and this deposit will cause damage to the outer lead. There also remains the problem that the insulation resistance between the outer leads is reduced, reducing the reliability of the electronic component mounting board.

The present invention was developed in view of the above-mentioned circumstances, and its purpose is to eliminate exposed metal parts of electronic component mounting boards even if only a partial cutting process is performed using a laser beam. Formation can be performed reliably and within a short time over a relatively wide area, and no fine dust is generated.
Another object of the present invention is to provide a method for easily manufacturing a highly reliable electronic component mounting board.

(Means for Solving the Problems) The means taken by the present invention to solve the above problems are explained using the reference numerals used in the examples. (12) is integrated, and a predetermined portion of the metal layer (11) is exposed from the base material layer (12) through the following steps. Method.

(a) Metal layer (11) in the part that should become the exposed part (IIA)
) and the base material layer (12), and then the mask (16) is placed between the metal layer (11) and the base material layer (12).
(b) a step of integrating the metal layer (1) located around the mask (16);
1) For the base material layer (12) of l, this base material layer (12)
A step of cutting the base material layer (12) around the mask (16) by irradiating the metal layer (11) side with a laser beam from the side; (c) cutting the base material layer (12) on the mask (16); ) together with this mask (16); and (d) a step of polishing at least the cut end of the base layer (12) and the metal layer (11) in the vicinity thereof by jet scrub polishing.

That is, in the method of the present invention, first, (a
), in order to prevent the metal layer (11) and the base material layer (12) from being integrated in the portion that should become the exposed portion (IIA), a mask (16) is placed between them. , the other portions of the metal layer (11) and the base material layer (12) are integrated.

This mask (16) is used in a series of processes for manufacturing this electronic component mounting board (10), such as the process of integrating the metal layer (11) and the base material layer (12), due to shocks such as heat and pressure. Any material may be used as long as it does not deform even when added and can be finally peeled off from the metal layer (11) by some method, such as a relatively heat-resistant resin film, metal foil, etc.

In addition, integrating the metal layer (11) and the base material layer (12) means that the thermosetting resin before being completely cured is transferred to the metal layer (11).
This is done by adhering the metal layer (11) and the base material layer (12) by applying an appropriate temperature and time while bringing them into close contact with each other. This integration method includes a method of stacking the prepreg (12b) on the metal layer (11) and bonding the prepreg (12b) with heat using a press or the like to form the prepreg (12b) as the base material layer (I2); A method of forming a base material layer (12) by placing a semi-cured adhesive sheet (12a) between the base material layer (11) and the base material layer (12) and bonding the adhesive sheet under heat using a press or the like; a metal layer (11); Examples include a so-called injection molding method, in which a thermosetting resin is injected into a mold in which the resin is sandwiched, and the thermosetting resin is thermosetted to form the base layer (12).

Next, for the base material layer (12) as described above, (
As shown in b), the laser beam is irradiated from the outside of the base layer (12) to the base layer (12) on the metal layer (11) located on the outer periphery of the mask (16). be.

The laser beam used here needs to cut the base material layer (12) well and avoid scratching the metal layer (11), so the laser beam has a high reflectance on metal. wavelength is preferable. The oscillation wavelength at that point is 10.6
When using a carbon dioxide laser with a diameter of μm, a metal layer (11
) can be cut without damaging the base material layer (12) at all.

In this way, by cutting the base material layer (12) on the metal layer (11) located on the outer periphery of the mask (16) with laser light, the mask can be cut as shown in FIG. 6(b). (16) on the outer periphery of the base material layer (16).
2) and the other base material layer (12) are formed.

If such a groove located on the outer periphery of the mask (16) is formed, the base material layer (12) located on the mask (16)
is completely separated from the other base material layer (12), and as mentioned above, the mask (16) and the metal layer (11) are not bonded, so the mask (16) can be easily peeled off. It has become a state.

Next, when the base material layer (12) and the mask (16) are peeled off from the metal layer (11), the metal exposed portion (IIA) is completed as shown in FIG. 6(c).

Finally, as shown in FIG. 6(d), the cut end of the base material layer (12) and the metal layer (11
) is polished by jet scrub polishing, an electronic component mounting substrate (10) having an exposed metal portion (IIA) is formed.

Here, jet scrub polishing is a method of stirring particles such as silicon oxide in water at a concentration of about 20%, and jetting the particles at a predetermined pressure from a nozzle onto the object to be polished, thereby polishing the object. Therefore, compared to ultrasonic cleaning or polishing using high-pressure water, it is more effective in removing substances altered by the heat of laser light.

Note that the areas where jet scrub polishing is performed are based on the base material layer (
The treatment may be performed not only on the cut section 12) and the metal layer (11) in the vicinity of this cut section, but also on the entire base material layer (12).

(Actions of the Invention) When the metal exposed portion (IIA) of the electronic component mounting board (IO) is formed by such a method, the following effects occur.

A mask (16) prevents the base material layer (12) and the metal layer (11) from forming a body in a portion to become the metal exposed portion (IIA). That is, even if the adhesive sheet (12a) for bonding the base material layer (12) and the metal layer (11) is one that has high resin flowability during thermocompression bonding, the mask (16) may interfere with the adhesive sheet (12a). Exposed metal part (IIA)
Since it is possible to prevent the resin of the adhesive sheet (12a) from flowing out onto the surface of the adhesive sheet (12a), the adhesive sheet 1 (12a) having excellent properties such as heat resistance, moisture resistance, and chemical resistance can be adopted.

Furthermore, if a carbon dioxide laser having an oscillation wavelength of 10.6 μm is used, a laser beam with a high reflectance for metals can be obtained, and resins, glass cloth, etc. can be cut well. Therefore, if laser light is irradiated from the base material layer (12) side to the metal layer (11) side, the metal layer (
Only the base material layer (12) is selectively cut without damaging the base material layer (11).

Therefore, even if the thickness of the base material layer (12) varies slightly, the cutting by the laser beam will always stop at the surface of the metal layer, so the cutting depth can be easily and accurately controlled. be.

Further, this laser beam processing may be performed on the base material layer (12) of the metal layer (11) J: located on the outer periphery of the mask (16).
), this processing work can be completed within a very short time because there is no need to perform the same work on the other parts.

Furthermore, since machining using laser light is non-contact machining, damage to tools during machining work can be completely ignored, and stable machining can be performed.

Furthermore, in the final step, the cut base material layer (1
Since the cut section 2) and the metal layer (11) in the vicinity thereof are polished by jet scrub polishing, it is possible to easily remove the altered substances attached to these parts due to the heat of the laser beam, thereby preventing the generation of fine dust. First, it becomes possible to obtain a highly reliable electronic component mounting board (10).

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

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

In the case shown in FIGS. 1 and 2, an internal connection part (IIC) is physically formed inside a plurality of outer leads (17a), and a base material layer is formed on both sides of this internal connection part (IIc). (1
2) allows each outer lead (17a) to protrude from the base material layer (12), and the conductor circuit (14) formed on at least one of the base materials.
) and an outer lead (17a) are electrically connected to each other and an electronic component mounting board (10).

This electronic component mounting board (10) includes an electronic component (20)
The electrical connection between the outer lead (17a) and the outer lead (17a) is made through the conductor circuit (14) of the base layer (12) J-. The inner connecting portion (IIC) is formed integrally with the inner connecting portion (IIC). Therefore, in this electronic component mounting board (10), the base material layer (12) is integrally provided on both sides of the internal connection part (lIC) that constitutes the metal layer (11), and the outer lead ( 17a) protrudes outward from this base layer (12). Then, this electronic component mounting board (lO) has a base material layer (12) J-
The conductor circuit (14) and the outer lead (17a) are connected through a through hole (
15), it is characterized by being electrically connected.

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

■First, apply a mask to cover both sides of the part that will become the outer lead (17a) of the lead frame (17) (this corresponds to the metal layer (11)) formed by etching the lead frame material. (16) is placed, prepreg and copper foil are layered on the outside in this order, and these are thermocompressed using a press to form a laminated body. As a result, as shown in FIG. 3(a), in the portion that should become the outer lead (17a), the mask (16) prevents the lamination and integration with the base material layer (12), and the lead frame (17) is the base material layer (12
) is formed.

In this Example 1, the lead frame material has a thickness of 0.2
A 5 mm copper alloy plate was used, and a so-called glass triazine prepreg, which was prepared by impregnating a glass cloth with a bismaleimide triazine resin and making it into a semi-hardened state, was used as the prepreg. Further, as the mask (16), a 50 μm thick polyphenylene sulfide film, so-called PPS, was used.

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

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

■ Next, by cutting the base material layer (12) on the metal layer (11) located on the outer periphery of the mask (16) using a carbon dioxide laser, the outer periphery of the mask (16) is cut. When a groove is formed to reliably separate the base layer (12) from the other base layer (12), the mask (16) and the outer lead (17a) are not bonded to each other, so the outer lead (17a) The upper mask (16) and the base material layer (
12) is completely separated from other parts.

If similar laser processing is performed from the back side, it will become (c) in Figure 3.
) is formed.

■Next, the mask (16) on the outer lead (17a)
) and the base material layer (12) are peeled off.

■Finally, as shown in FIG. 3(d), the cut end (cut end surface) of the cut base material layer (12) and the metal layer (11) in the vicinity thereof (in this example, the outer lead (17a))
) is polished by jet scrub polishing, an electronic component mounting board (10) as shown in FIG. 2 is formed.

Note that the jet scrub polishing used here has a particle size of 2.
Particles of No. 20 silicon carbide were stirred in water to a concentration of about 20%, and the particles were discharged through a nozzle at a pressure of 2.0 kg/cm 2 .

Electronic component mounting substrates (10
), the outer lead (1
Since the outer lead (17a) is not damaged, the physical strength such as bending strength and pull-out strength of the outer lead (17a) is not deteriorated.

In addition, electronic component mounting substrates manufactured by this method (
It was confirmed that the insulation resistance between the outer leads (17a) of No. 10) was improved by one order of magnitude compared to that without jet scrub polishing.

Next, a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. The electronic component mounting board (10) shown in FIG. 18), and its manufacturing method will be described below with reference to FIG.

■First, thickness 1. Mask (16) on the part that should be the exposed metal part (IIA) of the Omm aluminum plate (IIB)
is placed, and an adhesive sheet (12a) and a base material layer (
12) and heat-compression bonded with a press to form an aluminum plate (
IIB) and the base material layer (12) are laminated and integrated to form a substrate as shown in FIG. 5(a).

Here, an aluminum foil with a thickness of 25 μm was used as the mask (16), and a semi-cured film containing epoxy resin as a main component was used as the adhesive sheet (12a). Further, as the base material layer (12), a completely cured glass epoxy prepreg was used.

■Next, the base material layer (12) on the metal layer (11) located on the outer periphery of the mask (16) is cut using a carbon dioxide laser to form a shape as shown in FIG. 5(b). A substrate is formed.

(2) Next, the mask (16) and base material layer (12) on the exposed metal portion (IIA) are peeled off.

■Finally, as in Example 1, as shown in FIG. 5(d), the metal layer (11) (metal exposed portion (IIA) ) by jet scrub polishing, the metal layer (11) is exposed in the recess (13) for mounting electronic components and the heat dissipation part (18).
is formed.

Of course, this heat dissipation part (18) is a board for mounting electronic components (l
It can be formed on both sides of O), and in that case, higher heat dissipation properties can be obtained.

(Effects of the Invention) As described in detail below, in the present invention, as exemplified in the above embodiment, a base material layer is integrated with a metal layer, and the metal layer is formed from this base material layer. A method of manufacturing a board for mounting electronic components, which is constructed by exposing a predetermined portion through the following steps.

(B) A step of arranging a mask between the metal layer and the base layer in the portion that should become the exposed portion, and then integrating the base layer with the metal layer; (B) Surroundings of the mask A step of cutting the base material layer around the mask by irradiating a laser beam from the base layer side to the metal layer side with respect to the base material layer on the metal layer located on the mask; (d) a step of polishing at least the cut end of the base layer and the metal layer in the vicinity thereof by jet scrub polishing.

Therefore, according to the present invention, even if the laser beam cutting process is only partial, the exposed metal portions on the electronic component mounting board can be formed reliably and in a short time over a relatively wide area without damaging the metal layer. In addition, it is possible to easily manufacture a highly reliable electronic component mounting board without generating fine dust.

That is, according to the manufacturing method according to the present invention, not only can the exposed metal parts constituting the electronic component mounting board be formed reliably and within a short time, but also because the process is a non-contact process using laser light. , tool damage during machining operations can be completely ignored.

In addition, since the mask is placed on the part that should be the exposed metal part, when the metal layer and the base material layer are integrated, the resin will not adhere to the surface of the part that should be the exposed metal part, so for example, thermocompression bonding An adhesive sheet that has relatively high time resistance can be used.

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

Furthermore, due to the laser beam's ability to cut resin much better than metal, even if the base material layer is completely cut, the metal layer will not be damaged. Control can be performed reliably, and the performance related to the physical strength of the metal layer does not deteriorate.

In addition, since the cut ends of the cut base material layer and the metal layer in the vicinity are polished by jet scrub polishing, it is possible to easily remove the altered substances that adhere to these parts due to the heat of the laser beam, thereby removing fine particles. etc., and a highly reliable electronic component mounting board can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged plan view of an electronic component mounting board formed by the manufacturing method according to the present invention, and FIG. 2 is a partial enlarged plan view of FIG.
- A cross-sectional view taken along line n, each of (a) to (d) in FIG. FIG. 4 is a perspective view of another electronic component mounting board formed by the manufacturing method according to the present invention, and each of (a) to (d) in FIG. 5 shows the electronic component mounting board shown in FIG. Each of FIGS. 6(a) to 6(d) is a partially enlarged cross-sectional view showing the progress during manufacturing of yet another electronic component mounting board formed by the manufacturing method according to the present invention. figure,
FIG. 7 is a sectional view showing an example of an electronic component mounting board. Explanation of symbols 10...Substrate for mounting electronic components, 11...Metal layer, 11
A...Metal exposed part, IC...internal connection part, 12.
... Base material layer, 12a ... Adhesive sheet, 12b ... Prepreg, 13 ... Recessed part, 14 ... Conductor circuit, 15.
-Through hole, 16...Mask, 17...Lead frame, 17a...Outer lead, 18...Heat radiation part, 20...Electronic component. that's all

Claims (1)

[Claims] A substrate for mounting electronic components, which is constructed by integrating a base material layer with a metal layer, and exposing a predetermined portion of the metal layer from the base material layer through the following steps: manufacturing method. (B) A step of arranging a mask between the metal layer and the base layer in the portion that should become the exposed portion, and then integrating the base layer with the metal layer; (B) Surroundings of the mask A step of cutting the base material layer around the mask by irradiating a laser beam from the base layer side to the metal layer side with respect to the base material layer on the metal layer located on the mask; a step of peeling off the base material layer along with the mask; (d) a step of polishing at least the cut end of the base material layer and the metal layer in the vicinity thereof by jet scrub polishing.