JP3741931B2 - Method for manufacturing electronic circuit device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic circuit device in which a driver IC, a memory IC, a controller IC, etc. used in a portable device or the like, an electronic notebook or a liquid crystal display device are mounted on a bare chip.
[0002]
[Prior art]
Conventionally, the following techniques are known as techniques used in electronic circuit devices in such fields.
[0003]
ICs used for face-down mounting of semiconductor bare chips have bumps on the pads that have bump electrodes called solder, gold, silver, copper, nickel, palladium, etc., alone or in combination, plating, vapor deposition, sputtering, printing, It is formed by a method such as wire bonding.
[0004]
Bonding to the circuit board is performed by conductive adhesive, anisotropic conductive adhesive, contact between electrodes (mechanical contact), metal diffusion / melting / eutectic, etc. via bumps.
[0005]
When a flexible substrate is used as the circuit board, a copper thin film or aluminum thin film is laminated on an insulating film of polyimide or PET by an adhesive or directly formed, and a conductor pattern is formed by a wet or photo process. An insulating film called an overcoat or a resist is formed for the purpose of pattern protection other than the joint on the conductor pattern. The thickness is about several μm to several 100 μm. The joint with the part is opened so that the pattern can be joined. The opening is formed using a printing method or a photo process method. FIG. 6 shows the IC mounting unit. As shown in the figure, a window 2 is opened in the insulating coating on the flexible substrate 1 with a margin around the periphery of the IC 3 and slightly larger (about 0.1 mm to several mm) than the outer shape of the IC. Depending on the bonding method, tin, solder, gold, nickel, palladium, silver, or the like may be formed on the conductor pattern in the opening by a method such as plating, printing, dipping, or the like.
[0006]
The sealing resin for protecting and reinforcing the IC joint is supplied by applying it around the IC in a liquid state, and by flowing, it fills the gap between the IC and the flexible substrate and the periphery of the IC. It is cured by light, anaerobic condition, reaction of two liquids alone or in combination. As the sealant, an epoxy-based resin, an acrylic-based resin, or a resin in which both are combined is used, and additives, fillers, and the like that are combined with various properties such as thermal expansion, viscosity, and curing conditions may be included. In addition, heat may be applied to the substrate or the resin itself for viscosity adjustment during application.
[0007]
[Problems to be solved by the invention]
When the surface of the insulating coating on the flexible substrate has low wettability with respect to the sealing resin before curing (that is, high water repellency), the contact angle between the sealing resin and the insulating coating is increased.
[0008]
As a result, when the sealing resin is applied to the periphery of the IC, the sealing resin stays on the insulating coating, and there is a problem that the gap between the IC and the flexible substrate and the periphery of the IC may not be filled. This will be described with reference to FIGS. The flexible substrate 1 has a conductor wiring 8 formed on the insulating film 9 and an insulating film provided thereon, and the bump 6 formed on the IC chip 3 and the conductor wiring 8 are connected. Yes. When the contact angle between the sealing resin and the insulating coating is large, the sealing resin 5 applied to the insulating coating window portion 2 stays on the insulating coating as shown in the figure, and the IC 3 and the flexible substrate 1 It is not filled around the gap or IC3.
[0009]
In addition, if a large window is opened in the insulating film with a large margin at the periphery of the IC in order to improve the filling property of the sealing resin, a large amount of the sealing resin may be required to protect the exposed pattern. In other words, a conductor pattern portion that is not protected by either the insulating coating or the sealing resin is generated. As a result, problems such as an increase in cost and man-hours and a decrease in reliability occur.
[0010]
Accordingly, an object of the present invention is to provide an electronic circuit device capable of maintaining reliability and dramatically increasing the filling property of the sealing resin while suppressing an increase in cost and man-hours.
[0011]
[Means for solving problems]
In the electronic circuit device of the present invention, an IC on which bumps are formed is connected face-down to a flexible substrate in which a conductor wiring is formed on an insulating film and an insulating coating is applied to a part of the surface. Sealing resin is applied and filled in the gaps and the peripheral part of the gap and cured.
[0012]
Then, the insulating coating of the flexible substrate is formed in a slit shape or a wedge shape in the vicinity of the sealing resin application portion around the IC, so that the sealing resin has a good wettability and does not include the insulating coating (that is, the slit Or the wedge portion), so that the insulating coating window is not opened more than necessary, and after application of the sealing resin, it is guided to the IC chip via the slit portion or the wedge portion. It is possible to fill the gap and the periphery of the IC chip.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The electronic circuit device of the present invention will be described below with reference to the drawings.
[0014]
FIG. 1 is a top view before the sealing resin is applied. In the flexible substrate 1, an insulating coating window 2 is open around the mounting portion of the IC chip 3. In addition, insulating coating slits 4 are formed in a total of four locations in the outer direction so as to be connected to the insulating coating window 2 slightly outside the four corners of the IC chip, which is the application portion of the sealing resin.
[0015]
FIG. 2 is a top view of the vicinity of the IC immediately after application of the sealing resin. The sealing resin 5 applied in the vicinity of the insulating coating slit 4 smoothly flows into the insulating coating window 2 via the insulating coating slit 4 while minimizing the influence of the water repellency of the insulating coating, The gap between the periphery of the IC chip 3 and the flexible substrate 1 and the periphery of the IC chip 3 are filled.
[0016]
FIG. 3 is a cross-sectional view of the vicinity of the insulating coating slit after application of the sealing resin. The IC chip 3 and the flexible substrate are connected by the bumps 6 formed on the IC chip 3 and the conductor wiring 8 formed on the insulating film 9. The sealing resin 5 applied to the insulating coating slit 4 flows into and fills the gap between the IC chip 3 and the flexible substrate and the peripheral part of the IC chip 3.
[0017]
FIG. 4 shows a top view of the vicinity of the IC after the sealing resin is filled according to the present invention. After a certain period of time, the sealing resin 5 is neatly filled in the gap between the IC chip 3 and the flexible substrate and the peripheral part of the IC chip 3. Thereafter, the sealing resin 5 is cured to complete the electronic circuit device according to the present invention.
[0018]
FIG. 5 is a top view before the sealing resin is applied according to another embodiment. In this embodiment, a case where the sealing resin 5 is applied to the vicinity of two central portions on the long side surface of the IC chip 3 is shown, and an insulating coating wedge portion 10 is connected to the insulating coating window 2 near the coating portion. It is formed in two places. When the sealing resin is applied, the influence of the water repellency of the insulating coating is minimized as in the above-described embodiment, and smoothly flows into the insulating coating window 2 via the insulating coating wedge 10 and the periphery of the IC chip 3 And the gap between the flexible substrate 1 and the periphery of the IC chip 3 can be filled.
[0019]
Each example described above shows a typical configuration. Actually, the number, position, shape, and combination of the insulating coating slit portion and the insulating coating wedge portion are the size of the IC, the application position and the application amount of the sealing resin. It can be set arbitrarily according to the specifications of the insulation coating and conductor wiring.
[0020]
The shape of the insulating coating slit (if it is connected to the insulating coating window is considered as one side), any of the shapes including trapezoids, rectangles, triangles, and curves that image a narrow gap (slit) Then, assuming that the width is about 10 μm to 2 mm, the length is about 100 μm to 5 mm, and the angle with respect to the IC is a rectangle of the IC shape, the angle of the slit center line is set within a range of about 30 to 150 degrees from each side. .
[0021]
The shape of the wedge portion of the insulating coating (if it is connected to the insulating coating window is considered to be one side), the shape of the wedge is a triangle or a shape including a curve, with a width of about 10 μm to 5 mm, The length is set in the range of about 50 μm to 5 mm.
[0022]
The position of the insulating coating slit portion or the insulating coating wedge portion includes or is close to the sealing resin application position (the shortest part is within a distance of about 2 mm from the center of the application position), and the sealing resin can be guided near the IC. Must be a position / angle. As the sealing resin application position, about 1 to 20 points of application to the vicinity of the corners of the IC and the insulating coating window, the central part of the corner, the equally divided part, etc., or the line application along the side is 1 to 8 It is set in the range of about two places or about two to eight places by a combination of dot coating and line coating.
[0023]
The application amount of the sealing resin is set in a range of about 0.001 mg to 5 g per place.
[0024]
【The invention's effect】
According to the electronic circuit device of the present invention, the insulating resin coating on the flexible substrate is formed in a slit shape or a wedge shape in the portion where the sealing resin around the IC is applied. It will be applied to the part that does not contain the insulation coating, and it will be smoothly guided through the slit after applying the sealing resin without opening the window of the insulation coating more than necessary, and the gap between the IC chip and the flexible substrate and It becomes possible to fill around the IC chip.
[0025]
That is, it is possible to provide an electronic circuit device capable of maintaining reliability and dramatically increasing the filling property of the sealing resin while suppressing an increase in cost and man-hours.
[Brief description of the drawings]
FIG. 1 is a top view before applying a sealing resin of the present invention.
FIG. 2 is a top view of the vicinity of an IC immediately after application of a sealing resin according to the present invention.
FIG. 3 is a cross-sectional view of the vicinity of an insulating coating slit portion after application of a sealing resin according to the present invention.
FIG. 4 is a top view of the vicinity of an IC after filling with a sealing resin of the present invention.
FIG. 5 is a top view of another embodiment of the present invention before application of a sealing resin.
FIG. 6 is a top view before applying a conventional sealing resin.
FIG. 7 is a top view of the vicinity of an IC after applying a conventional sealing resin.
FIG. 8 is a cross-sectional view of the vicinity of a conventional sealing resin application portion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Flexible substrate 2 Insulating film window 3 IC chip 4 Insulating film slit part 5 Sealing resin 6 Bump 7 Insulating film 8 Conductor wiring 9 Insulating film 10 Insulating film wedge part

Claims (1)

A process for producing a flexible substrate by providing a conductive wiring and an insulating film having a window on the insulating film;
A step of face-down mounting the IC on which the bump is formed on the flexible substrate at the window portion of the insulating coating;
The insulating film has better wettability than the insulating coating, and the insulating coating is formed with a slit portion or a wedge portion continuous with the window. The slit portion or the wedge portion and the insulating coating are formed on the insulating coating. Applying a sealing resin so as to straddle ;
And a step of curing the sealing resin filled into the gap between the IC and the flexible substrate.

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