JP2911241B2 - Manufacturing method of hybrid integrated circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a hybrid integrated circuit in which a part of a circuit pattern is used as an external lead.

[0002]

2. Description of the Related Art FIG. 13 is a cross-sectional view illustrating a folded board type hybrid integrated circuit as a conventional hybrid integrated circuit. Referring to the figure, the insulating metal substrates (60) and (62) are made of aluminum having a thickness of 0.5 mm to 2.0 mm with anodized surfaces, and slits formed in the aluminum substrate (not shown). ) Are cut to form two insulating metal substrates (60) and (62).

The thickness of the insulating layer (64) is several tens μm to several hundreds of μm. Through this insulating layer (64), the thickness of the insulating layer (64) is several tens μm, and the conductive path is formed by a subsequent photo-etching process. Then, a copper foil having various pads and the like formed in a predetermined shape and serving as a conductive layer (66) is thermocompression-bonded by a hot press. Therefore, the insulating layer (64) of the bent board type hybrid integrated circuit is flexible,
A polyimide resin having adhesiveness is used.

[0004] The copper foil is photo-etched before dividing the aluminum substrate, and the respective insulated metal substrates (60), (62)
Various pads and conductive paths such as a die bond pad for mounting a semiconductor element thereon, a pad for fixing an external lead (70) by soldering, and a conductive path are formed in a predetermined shape and a conductive layer (66).
Is configured. Further, conductive paths for connecting circuits on the respective insulating metal substrates (60) and (62) are formed in the slit portions of the aluminum substrate. The line width of the circuit pattern of the conductive layer (66) is several tens μm to several hundred μm.

The external leads (70) are frame-shaped and have conductive layers (6).
After the hybrid integrated circuit is molded or encapsulated in a case, the frame is cut off to form individual external leads (70) by soldering to the pad of 6).

[0006]

The above-mentioned operation of fixing the external lead (70) of the conventional hybrid integrated circuit is performed by using an external lead terminal.
Since all the relative positions and angles of (70) and the pad must be matched, it is extremely complicated. Further, in the external lead (70), a portion to be solder-fixed to the pad of the conductive layer (66) is made larger in size than other portions in order to maintain the fixing strength, so that a larger margin is provided. As a necessity, there is a problem that the pad area of the conductive layer (66) cannot be reduced despite other circuit patterns being finer.

Furthermore, since the bonding performance of the polyimide resin as the insulating layer (64) to the copper foil is not perfect, the pad may be peeled off immediately after the external lead (70) is fixed due to residual stress of the frame or the like. Therefore, the insulating layer (64) of the bent board type hybrid integrated circuit has a problem that, in addition to the polyimide resin, an epoxy resin having good adhesiveness between the polyimide resin and the copper foil must be used. . Furthermore, in the bent board type hybrid integrated circuit, the circuit formed on the conductive layer (66) on the side to which the external lead (70) is not fixed is connected to the external lead (70).
If a connection to the
(66) must be routed in a longitudinal direction, and there is a problem that the effective substrate area is reduced.

[0008]

The main feature of the present invention is to remove an insulating resin layer of a conductive path patterned in a lead shape by selective irradiation of an excimer laser, and to use the conductive path as an external lead. And

[0009]

Since the insulating resin layer under the lead-shaped conductive path is removed by an excimer laser, the removal of the insulating resin layer is complete and the lead-shaped conductive path is not damaged or deformed. In addition, since the external leads have a simple shape, a small-sized and inexpensive hybrid integrated circuit can be obtained, and soldering of the external leads to another substrate can be performed in close proximity to the hybrid integrated circuit, so that mounting efficiency is improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. Referring to FIGS. 1 and 2, the insulating metal substrate (10) has a thickness of 0.5 in consideration of heat radiation characteristics and workability.
Aluminum (12) having a thickness of 2.0 mm to 2.0 mm is used, and the surface is anodized to form an oxide film (14) having a thickness of 3 μm to 30 μm. The insulating metal substrate (10) has a size of several tens of units of the hybrid integrated circuit, and a slit (16) having a width at least twice as large as the thickness of the insulating metal substrate (10) is formed at the boundary of the unit hybrid integrated circuit.
Are formed by punching.

Referring to FIG. 2, the copper foil (20) has a thickness of about 50 μm.
An A-stage epoxy resin having a high fluidity is applied to the surface thereof using a roller coater, and the epoxy resin is semi-cured to form a B-stage adhesive layer.
(22) is formed. The thickness of the copper foil (20) is appropriately changed in consideration of the size, cost, and pattern rules of the hybrid integrated circuit.

In this step, a copper foil (20) having an adhesive layer (22) formed on an insulating metal substrate (10) is hot-pressed,
Temperature 130 ° C-150 ° C, 10Kg / cm2
Thermocompression bonding is performed at a pressure of 50 kg. The adhesive layer (22) is completely cured by this thermocompression bonding step to have a film thickness of about 20 μm.
Then, the insulating metal substrate thermocompressed by the adhesive layer (22)
(10) and copper foil (20) for 5 hours to 10 hours at a temperature of 130 ° C.
After the adhesive layer (22) is cured while being kept at ~ 150 ° C, it is sent to the next step.

FIG. 3 and FIG. 4 which is a sectional view taken along line AA of FIG.
Referring to, a photoresist (not shown) applied using a roller coater is selectively exposed in accordance with a circuit pattern to form a mask, and the copper foil (20) is selected with a ferric chloride solution using the photoresist as a mask. Etched to form a lead-like conductive path as shown in FIGS. 3 and 4 on a copper foil (20).
(24), all the circuit patterns such as the die bond pad (26) and the wire bonding pad (28) are formed for each unit hybrid integrated circuit divided by the slit (16). The line width of the conductive path in this circuit pattern is usually several tens μm to several hundred μm, and the lead-shaped conductive path (24) formed above the slit (16) is formed with a line width of several hundred μm or more. .

Referring to FIG. 5, an excimer laser (indicated by an arrow) using KrF, XeCl, or ArF as a laser gas is selectively irradiated from a slit (16) of the insulating metal substrate (10) to thereby irradiate the insulating metal substrate ( The adhesive layer (22) exposed by the slit (16) of (10) is removed leaving the insulating portion (30).

The excimer laser processing will now be described with reference to FIG. In FIG. 12, the abscissa of the log scale is the energy density of the excimer laser (Fluence mJ), and the ordinate is the processing amount (Etch Depth μm) of each polymer and metal per laser shot.

YAG, which has been conventionally used in the industry,
In infrared laser processing such as CO2, a thermal mechanism is used in which a laser beam is condensed by a lens, and a processing object in a high energy density region near the focal point is melted and evaporated. Therefore, the infrared laser processing has a characteristic that the material to be processed is not selected, and also has a property that continuous thermal influence on the periphery of the processing portion is unavoidable.

On the other hand, in excimer laser processing, an excimer laser is irradiated to a processing object in a defocused state,
Processing is performed by an ablation process in which photons of an excimer laser molecularly break molecular bonds on the surface to be processed. Therefore, the excimer laser processing is a non-thermal processing, and the energy density (threshold) at which the processing is started differs greatly depending on whether the processing target is a molecular bond or a metal bond. This threshold is about 100 mJ / cm 2 for all polymers and about 1 for metals.
J. In addition, excimer laser processing is performed by molecular chemistry.
It has the characteristics of no pollution.

Referring again to FIG. 5, the insulating metal substrate (10)
The slit (16) is above the polymer threshold,
100m per unit area below the metal threshold
When an excimer laser having an energy density of J to 1J is irradiated, a part of the adhesive layer (22) exposed by the slit (16) is removed, leaving only the lead-shaped conductive path (24) in the slit (16). It is. Note that the adhesive layer (2
2) is 10 excimer lasers of 500 mJ per square cm.
Completely removed by 0 shots.

FIG. 6 and FIG. 7 which is a sectional view taken along the line BB of FIG.
Here, here, in order to improve the positional accuracy in the subsequent die bonding process and the wire bonding process, the slit (16) formed in the insulating metal substrate (10) is punched to form a more accurate shape. It is divided into unit hybrid integrated circuits. In this embodiment, one end of the lead-shaped conductive path (24) is a free end.
By forming a bridge interconnecting one end of 4), or leaving the adhesive layer (22) in a bridge shape at one end of the lead-shaped conductive path (24) during excimer laser processing of the adhesive layer (22). This prevents the lead-shaped conductive path (24) from being deformed.

Referring to FIG. 8, the die bond pad (26)
After fixing the integrated circuit element (32) using a brazing material such as silver paste, and further fixing an odd-shaped component such as a chip resistor (not shown) and a chip capacitor to predetermined pads by soldering, the integrated circuit element (32) Electrodes and wire bonding pads (2
8) are connected by a bonding wire (34) to complete the illustrated hybrid integrated circuit.

The assembly of the hybrid integrated circuit according to the present invention will now be described with reference to FIG. In the hybrid integrated circuit according to the present invention, after the insulated metal substrate (10) is fixed to a predetermined position of the mother substrate (40) by bonding or the like, the lead-like conductive path (24) is used as an external lead, and the predetermined position of the mother substrate (40) is Used by connecting to the pad (42). At this time, the insulating portion (30) left in the excimer laser processing step of the adhesive layer (22) prevents contact between the lead-shaped conductive path (24) and the insulating metal substrate (10).

Next, another embodiment of the present invention will be described with reference to FIGS. In the previous embodiment, the same hybrid integrated circuit pattern was formed in each area divided by the slit (16) in FIG. 1. However, as shown in FIG. (50) (52)
Can be divided and formed. In this embodiment, the surfaces opposite to the surfaces of the hybrid integrated circuit patterns (50) and (52) are opposed to each other, and the lead-like conductive paths (54) are bent and used as external leads. According to the present embodiment, since the external leads are formed in the middle of the two hybrid integrated circuit patterns (50) and (52), the conventional external leads are formed at either end of the two hybrid integrated circuit patterns. Compared with the hybrid integrated circuit, there is an advantage that the routing of the conductive path to the external lead is shortened.

Although the present invention has been described above, the present invention is not limited to the above-described embodiment. For example, the order of the step of fixing an integrated circuit element or the like and the step of dividing it into unit hybrid integrated circuits are arbitrary. It is also possible to carry out each step of the present invention for each single hybrid integrated circuit. In this case, notches are provided on four sides of the insulating metal substrate (10) instead of the slit (16). be able to.

[0024]

As described above, according to the present invention, since the excimer laser processing is performed, even when an epoxy resin which is difficult to chemically etch is used as the insulating resin layer, the insulating resin layer of the lead-shaped conductive path is completely formed. , And can be removed cleanly to form external leads. In addition, since the external lead structure is simple, a small-sized and inexpensive hybrid integrated circuit can be obtained, and soldering of the external leads to another substrate can be performed in close proximity to the hybrid integrated circuit, so that mounting efficiency is improved.

[0025]

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a manufacturing process according to an embodiment of the present invention, and is a plan view of an insulated metal substrate.

FIG. 2 is a sectional view of a manufacturing process according to the present invention.

FIG. 3 is a plan view of the manufacturing process of the present invention.

FIG. 4 is a view for explaining a manufacturing process of the present invention, and FIG.
Sectional view on the AA line of FIG.

FIG. 5 is a sectional view of the manufacturing process of the present invention.

FIG. 6 is a plan view of the manufacturing process of the present invention.

FIG. 7 is a view for explaining the manufacturing process of the present invention, and FIG.
BB sectional drawing of FIG.

FIG. 8 is a sectional view of the manufacturing process of the present invention.

FIG. 9 is a cross-sectional view of the manufacturing process of the present invention.

FIG. 10 is a plan view of a manufacturing process according to another embodiment of the present invention.

FIG. 11 is a sectional view of a manufacturing process according to another embodiment of the present invention.

FIG. 12 is a characteristic diagram illustrating processing characteristics of an excimer laser.

FIG. 13 is a sectional view of a conventional hybrid integrated circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Insulated metal substrate 22 Adhesive layer 24 Lead-shaped conductive path 26 Die bond pad 30 Insulating part 32 Integrated circuit element 34 Bonding wire

Claims (5)

(57) [Claims] 1. A copper foil pattern attached via an insulating layer
Having a lead-shaped conductive path above the slit.
Prepare and laser the insulating layer located in the slit of the substrate
Processing to remove the insulating layer under the lead.
Manufacturing method of a hybrid integrated circuit. Wherein said substrate is a metal substrate, removing the insulating layer of the lower lead-shaped conductive path such that the insulating layer positioned on the ground <br/> Tsu isolation portion is projected from the metal substrate 2. The method for manufacturing a hybrid integrated circuit according to claim 1, wherein: 3. The method for manufacturing a hybrid integrated circuit according to claim 1, wherein said substrate is divided at said slit to form a unit hybrid integrated circuit. 4. Before 2 or more sides of the unit hybrid integrated circuits
Claim 3, characterized in that to form a serial lead-shaped conductor path
Of manufacturing a hybrid integrated circuit. 5. The method of manufacturing a hybrid integrated circuit according to claim 1, wherein said circuit pattern is divided and formed in two adjacent regions of the copper foil divided by said slit.
Law.