JPS632157B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hybrid integrated circuit that can be mounted at high density and has excellent reliability, especially moisture resistance.

The development of mounting technology in recent years has been remarkable, and it is inexpensive and
Although there are increasing demands for miniaturization and high reliability, there is a limit to the number of electronic components that can be mounted on a given insulating substrate. Therefore, a method of mounting electronic components on both sides of an insulating substrate has been adopted to increase the density, but there is a problem in connecting both sides, which is undesirable in terms of cost and reliability.

The present invention provides an integrated circuit constructed by mounting electronic components on a heat-resistant film attached to an insulating substrate with a bendable slit in the center and formed with a patterned conductor. After coating the integrated circuit with resin without bending it, the integrated circuit is folded in half from the slit, and this folded integrated circuit is inserted into the through hole of the motherboard, so that the folded integrated circuit returns to its original unfolded state. The ends of this integrated circuit are connected to the motherboard by utilizing the restoring force of the integrated circuit to return to the original state, and a good connection is obtained.The hybrid integrated circuit is easy to increase density and has excellent reliability, especially moisture resistance. It is an attempt to obtain.

(Example) Hereinafter, a method for manufacturing a mixed integrated circuit according to an example of the present invention will be described in detail with reference to the drawings.

(Example 1) As shown in FIG. 1, an insulating substrate 1 made of a paper phenol substrate with slits 1a and a polyimide heat-resistant film 2 on which a patterned conductor was formed were bonded together using an adhesive tape. Next, an integrated circuit 3 consisting of a chip resistor, a chip capacitor, a mini-molded transistor, an IC, etc. is mounted on the heat-resistant film 2, and the connection terminals with the motherboard are masked with masking tape. mixed solvent
An epoxy resin containing 45 wt% and having a viscosity of 70 CPS was applied with a spray gun and cured at 80° C. for 30 minutes to form a coating resin layer 4 with a thickness of 50 μm, and then the masking tape was removed.

(Example 2) As in Example 1, an insulating substrate 1 made of a glass epoxy substrate with slits 1a and a polyimide heat-resistant film 2 on which a patterned conductor was formed were mixed with a two-component, solvent-free epoxy resin. It was attached using adhesive. Next, the same integrated circuit 3 as in Example 1 was mounted on the heat-resistant film 2, and after masking the connection terminals with the motherboard with masking tape, a solvent-free urethane-modified acrylic resin with a viscosity of 480 CPS was used as a dip. After coating and curing with ultraviolet rays to form a coating resin layer 4 having a thickness of 250 μm, the masking tape was removed.

Next, the insulating substrate 1 on which the block integrated circuit 3 obtained in Examples 1 and 2 was mounted was inserted into the slit 1a.
The two-folded insulating substrate was inserted into the through hole of the motherboard 5 as shown in FIG. 2, and connected with solder 6. This made it possible to achieve high density and to obtain a hybrid integrated circuit with excellent reliability, especially moisture resistance.

The insulating substrate used in the present invention is not limited to those commonly used as insulating substrates, such as a phenol substrate, a paper phenol substrate, a glass epoxy substrate, a paper polyester substrate, and an alumite-treated aluminum substrate. Furthermore, the reason why an insulating substrate with slits is used is that by bending it 180 degrees, an integrated circuit with electronic components mounted on both sides, which has excellent connection and insulation properties and can be increased in density, can be obtained. The conductor is formed by photoresist or etching, the heat-resistant film is preferably polyimide that can withstand the solder dip or solder reflow temperatures required to connect the electronic components and the conductor, and the heat-resistant film and insulating substrate are made of thermosetting resin or double-sided adhesive. Can be attached using tape.

By the way, the electronic components to be mounted are preferably chipped resistors, capacitors, mini-molded transistors, ICs, etc.
Mini-molded electronic components such as ICs have a short path between the leads and the device, so if they are temporarily fixed with adhesive and connected to a conductor by solder dip or solder reflow, the coefficient of thermal expansion is 1. Because of the order of magnitude difference, the reliability of the interface between the lead terminal and the molded resin decreases due to thermal shock, and the reliability, particularly the moisture resistance, decreases significantly. Furthermore, if chip resistors and chip capacitors are used with their functions trimmed using a laser in order to keep circuit constants constant, their characteristic values will become unstable if condensation occurs, so they must be coated with resin.

Resin coating materials include epoxy resins, acrylic resins, silicone resins, and polybutadiene resins, and there are solvent-free types that have been modified from these resins, as well as solvent-free types that have been modified with these resins, as well as solvent-free types that are coated with toluene, xylol, butyl acetate, methyl ethyl ketone, butanol, etc. as necessary. There are some added types.

In addition, the thickness of the resin coating layer is desirably 10 μm or more due to the need to provide the insulating substrate with a restoring force to return to its original flat state and moisture resistance.
If it exceeds 1 mm, cracks will occur when bending, which is undesirable.

As for the coating method, it is important to cover the insulating substrate on which the integrated circuit is mounted without bending it, and when the insulating substrate is inserted and connected to the motherboard in this state, there is no gap between the through hole and the insulating substrate. Even if this occurs, a good connection can be made because the insulating substrate has a restoring force to return to its original flat state. but,
If the insulating substrate is coated with dip or powder coating after bending, the insulating substrate will lose its restoring force.
Even if soldering is performed, it may cause a connection failure as shown in FIG. Therefore, it is preferable to apply the coating without bending it by dip, spray or screen printing.

As described above, according to the present invention, it is possible to obtain the restoring force of the insulating substrate to return to its original state by coating the insulating substrate with a resin including a heat-resistant film without bending it, and then folding it in half from the center. This allows the through-hole of the motherboard and the edge of the insulating board to be brought into close contact with each other, and there is no misalignment, resulting in a very good connection with the motherboard and making it easier to increase the density of hybrid integrated circuits. Moreover, a hybrid integrated circuit with excellent reliability, particularly moisture resistance, has been obtained.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing an embodiment of the present invention, and FIG. 3 is a cross-sectional view showing a connection failure when covering after bending. DESCRIPTION OF SYMBOLS 1...Insulating substrate, 1a...Slit, 2...Heat-resistant film, 3...Integrated circuit, 4...Coating resin layer, 5...Mother board, 6...Solder.

Claims (1)

[Claims] 1. An integrated circuit constructed by mounting electronic components on a heat-resistant film that is attached to an insulating substrate with a bendable slit in the center and formed with a patterned conductor, with the heat-resistant film not being bent. After coating with resin, the integrated circuit is folded in half through the slit, and the folded integrated circuit is inserted into a through hole of the motherboard, and the folded integrated circuit is restored to its original unbent state. A method of manufacturing a hybrid integrated circuit in which an end of the integrated circuit is connected to the motherboard using force.