JP2536574B2 - Hybrid IC resin coating method - Google Patents

Description

The present invention relates to a method of applying resin coating to a hybrid IC formed by mounting electronic circuit components such as integrated circuits (referred to as IC) and chip capacitors on a substrate. It is a thing.

<Prior Art> As is well known, a hybrid IC is one in which a thick film conductor circuit is formed on a substrate made of alumina, SiC, enamel, etc., and electronic circuit parts such as an IC and a chip capacitor are mounted. Substrates and electronic circuit components are coated with various resins such as silicone-based, epoxy-based, and urethane-based resins, that is, packaged, and reliability such as moisture resistance and impact resistance is improved.

A dip coating method is used for coating the resin. That is, as shown in FIG. 10, when the lead terminal 2 of the hybrid IC 1 is hung up on a hanger or the like (not shown) (see state a in FIG. 10),
A substrate 4 on which a chip component of IC1 or an electronic circuit component 3 such as an IC is mounted is dipped in a liquid resin 6 in a resin tank 5 (see state b in the same figure) and pulled up (see state c in the same figure). The resin layer 7 is dried and hardened by heating the IC1 (see FIG.
See state). Regarding the dip coating of the hybrid IC1, for example, Japanese Utility Model Publication No. 57-94903,
It is disclosed in JP-A-57-133603.

However, when the resin layer 7 is cured, the hybrid
The IC 1 is heated while the lead terminal 2 is held upward so that the IC 1 does not hang down and adhere to the lead terminal 2 before the resin layer 7 is cured. Hardened.

At this time, by the time the curing of the resin layer 7 is completed, the resin layer 7
Drips downward due to the action of gravity (so-called dripping)
However, a large amount of the resin adheres to the direction opposite to the lead terminal 2, that is, to the tip of the substrate 4 (see FIG. 10d).

Therefore, as shown in FIG. 11, when the hybrid IC1 is mounted on the circuit board 8, the center of gravity of the hybrid IC1 is located at a high position, which is disadvantageous in vibration resistance. Especially, single in-line package type (SIP type)
The hybrid IC is extremely disadvantageous in terms of vibration resistance due to its form, and countermeasures against it are desired.

Furthermore, higher vibration resistance is required for hybrid ICs mounted on vehicles, vehicles, and other moving bodies.

Further, as a conventional technique for improving the vibration resistance of the hybrid IC, for example, JP-A-57-94903, JP-A-61-61
-275670 is available.

In the former case, vibration is applied when the resin is coated on the electronic component so that the resin coating to be coated has a uniform thickness.

In the latter, the dummy element is purposely mounted on the surface of the SIP hybrid IC to lower the apparent center of gravity of the IC.

<Problems to be Solved by the Invention> In the former one that applies vibration to the electronic component, a considerable amount of dripping occurs until the resin is completely cured,
It is not enough to improve the vibration resistance. In addition, a complicated mechanical device is required to apply vibration to electronic parts,
The cost will be high.

Further, in the latter case where the dummy element is provided, the number of parts and the weight are increased, which is not a preferable measure.

It is easy to dry and cure the resin layer with the lead terminals facing down immediately after coating, but this will cover the lead terminals with the flowing resin, and mount the hybrid IC on the circuit board. At this time, that is, when soldering, the solder is repelled by the resin, which makes soldering difficult and cannot be put to practical use.

Therefore, an object of the present invention is to solve the above-mentioned problems in the conventional technique.

<Means for Solving the Problem> The present invention for solving the above-mentioned problems includes a step of coating a liquid resin on a hybrid IC, and a lead terminal facing upward at a predetermined temperature or lower and a lead terminal facing downward at a predetermined temperature or higher. While the hybrid IC is supported by a jig equipped with a reversing function, the process of drying the lead terminals facing upward at a specified temperature or lower, and the reversing function of the jig by heating above the specified temperature during drying And a resin coating method for the hybrid IC, comprising the step of inverting the hybrid IC and drying with the lead terminal facing downward.

<Operation> According to the above-mentioned means, the surface of the resin layer of the liquid resin is dried by supporting the hybrid IC coated with the liquid resin on the jig and drying it with the lead terminal facing upward at a predetermined temperature or lower. dry. After that, by heating to a temperature above a certain temperature, the hybrid can be operated by the inversion function of the jig.
The inside of the resin layer is dried and hardened by inverting the IC and drying with the lead terminal facing downward.

In this way, by inverting the hybrid IC during the drying process, the resin inside the resin layer can flow using gravity while preventing the resin from dripping onto the lead terminals due to the dried surface of the resin layer. , The center of gravity of the hybrid IC can be set at a low position.

<Example> An example of the present invention will be described below with reference to the drawings. The hybrid IC11 before resin coating is
A substrate 14 having lead terminals 12 as shown in FIG.
An electronic circuit component 13 such as a chip component or an IC is mounted on the.

In describing the coating method of the hybrid IC 11, first, the shape memory alloy jig 20 that supports the hybrid IC 11 will be described with reference to FIGS. The jig 20 has a rectangular flat plate shape having a base portion 21 at one end and a clip portion 22 at the other end. The base 21 has a support base 25.
Is removably fitted in a mounting groove 26 provided at the upper end of the. In addition, the clip 22 has a lead terminal of the hybrid IC 11.
12 ends are detachably inserted by utilizing the elasticity.

Then, the jig 20 deforms at a predetermined deformation temperature, which is the condition temperature TA in this example, into a low temperature state below that and a high temperature state above it. In a low temperature state, this jig 20 has an inverted U shape from the base portion 21 toward the tip as shown in FIG.
It is bent into a letter shape and is deformed into a state in which the clip portion 22 at the tip portion is directed downward (this state is referred to as shape PB).
In the high temperature state, as shown in FIG. 3, the base portion 21 becomes vertical toward the tip, and the clip portion 22 of the tip portion is deformed to a state in which it is directed upward (this state is referred to as shape PA). It is made of a shape memory alloy. That is,
As a characteristic of the shape memory alloy, when the shape PA is memorized at the first condition temperature TA and another shape PB is made at a different condition temperature TB (temperature TA or less), the shape memory alloy is deformed to the shape PB under the condition temperature TB, When the temperature reaches the condition temperature TA, the shape PB returns to the shape PA and is deformed. However, the condition temperature TA is a finger touch drying temperature TC of the resin layer 17 coated on the hybrid IC 11, that is, a dry state in which a fingerprint is not attached even if the fingertip is touched on the surface of the resin layer 17, and the inside is not yet formed. The temperature is set to be slightly higher than the temperature of the cured state (also referred to as the surface dry state).

Next, a batch type curing furnace 30 for heating the hybrid IC 11 will be described with reference to FIG.

Inside the outer case 31 with heating area 32, the heater
33 and Juan 34 are incorporated. The heating area 32 of the outer case 31 is provided with a shelf plate 35 on which the support 25 including the jig 20 can be placed. The support table 25 is put in and taken out of the heating area 32 via an opening / closing door (not shown).

By the rotation of the fan 34, the heat of the heater 33 is sent to the heating area 32 and the atmosphere in the heating area 32 is agitated. The heater 33 can switch and adjust the heating temperature. Therefore, the output of the heater 33 is adjusted so that the ambient temperature of the heating area 32 follows the heating profile shown in FIG. After the heating profile is heated from the heating start temperature TB to the touch drying temperature TC,
After TC is held for a predetermined time ta, it is heated to the curing temperature TD,
After holding the temperature TD for a predetermined time tb, the heating is stopped. Note that, for example, when the resin layer 17 is a thermosetting silicone resin, the temperature TA is about 80 ° C and the touch-drying temperature TC is about 70.
C., the curing temperature TD is set to about 120.degree. C., the time ta is set to about 30 minutes, and the time tb is set to about 60 minutes.

Next, a method of coating the hybrid IC 11 with a resin, in this example, a thermosetting silicone resin, using the jig 20 and the batch-type curing furnace 30 described above will be described.

First, the hybrid IC 11 is immersed in a liquid resin by a dip coating method as in the conventional case. That is, as shown in FIG. 5, in a state in which the lead terminal 12 is hung up on a hanger or the like (not shown) (see the state a in FIG. 5), the chip parts of the IC 11 and electronic circuit parts such as the IC are shown.
A substrate 14 on which 13 is mounted is dipped in a liquid resin (thermosetting silicone resin) 16 in a resin tank 15 (see state b in FIG. 13) and pulled up (see state c in FIG. 16). The hybrid IC 11 that has been subjected to the immersion treatment is left for a while at room temperature with the lead terminal 12 facing upward (see the state in FIG. 5D). Before this dip coating step, the jig 20 is attached to the lead terminal 12 of the hybrid IC 11 in advance.

Then, the base 21 of the jig 20 attached to the hybrid IC 11
2 is fitted into the mounting groove 26 of the support base 25 as shown in FIGS. 2 and 4, and is placed on the shelf plate 35 of the curing furnace 30 (see the solid line state in FIG. 1).

After the opening / closing door of the curing furnace 30 is closed, the heater 33 and the fan 34 are operated, and the atmosphere in the heating area 32 is heated according to the heating profile shown in FIG.

Then, the atmosphere temperature in the heating area 32 is maintained at 70 ° C., which is the touch-drying temperature TC, for the time ta (about 30 minutes), so that the resin layer 17 of the hybrid IC 11 is in the touch-free state, that is, the surface. The resin is in a dry state, and the surface of the resin is in a dry state. On the other hand, fluidity still remains inside the resin.

After that, when the ambient temperature in the heating area 32 gradually rises to 80 ° C. which is the condition temperature TA, the jig 20 moves to the shape PB
To the shape TA shown in FIG. 3 to support the hybrid IC 11 with its lead terminal 12 facing downward (first
(See the chain double-dashed line in Fig.).

When the hybrid IC 12 is inverted in this manner, the resin that has been trying to flow toward the tip of the substrate 14 until now begins to flow toward the base of the substrate 14. However, since the surface of the resin is already dry to the touch, it does not cause flow to the lead terminals 12, that is,
The lead terminal 12 is not covered with the coating resin. By the flow of the resin layer 17 toward the base of the substrate 14, the center of gravity of the hybrid IC 11 is located at a low position as shown in FIG. 3, and the vibration resistance is improved.

Furthermore, the ambient temperature rises and the curing temperature TD is about 12
The resin layer 1 is retained at 0 ° C for a time tb (60 minutes).
7 is completely dry and cured. That is, as described above, the resin layer 17 is cured at the position where the center of gravity of the hybrid IC 11 is low. After that, the hybrid IC 11 may be appropriately taken out from the curing furnace 30 and the jig 20 may be removed.

As described above, the hybrid IC 11 coated with the resin layer 17 is manufactured (see FIG. 6).

This hybrid IC11 can be used as a circuit board as shown in FIG.
When mounted on the 18, the center of gravity is at a low position, so good vibration resistance can be obtained.

Also, the shape memory alloy jig 20 that deforms depending on the heating temperature
By using, it is possible to invert the hybrid IC 11 at a low cost and with high reliability without requiring a special mechanical device or work. Further, since the shape memory alloy jig 20 can be repeatedly used, the running cost can be reduced.

According to the batch type curing furnace 30 in this example, the shelf board
By increasing or decreasing the number of 35 and jigs 20, any number of hybrid ICs 11 can be heated, and once the hybrid ICs 11 are set in the heating area 32, they can be heated according to a predetermined heating profile. Thus, the resin layer 17 of the hybrid IC 11 can be dried and cured without any work during heating.

Further, instead of the batch-type curing furnace 30 of the above embodiment,
The continuous curing oven 40 shown is also conceivable. This curing oven 40
In the outer case 41, the heating area 42 is the touch dry zone 42.
a and a curing zone 42b, and each zone 42a, 42
Heaters 43 are incorporated in the upper and lower parts of b.
The heater 43 may be provided only on one of the upper part and the lower part.

In addition, a belt conveyor is installed at the bottom of the outer case 41.
44 will be installed. The belt conveyor 44 conveys the support base 25 from the left side to the right side in the figure by the rotation of the belt 45, that is, conveys it from the inlet 41a to the outlet 41b through the touch drying zone 42a and the curing zone 42b of the heating area 42.

Then, the output of each heater 43 in each zone 42a, 42b of the heating area 42 is adjusted to a predetermined heating profile in accordance with the conveyance speed of the belt conveyor 44 (see, for example, FIG. 8).
If it is set so as to be realized, the hybrid IC 11 charged from the inlet 41a of the outer case 41 is heated in the same manner as in the case of the batch-type curing furnace 30, so that the hybrid IC 11 has a low center of gravity. Is discharged from the exit 41b.

The continuous curing furnace 40 can also dry and cure the hybrid IC 11 without adding any work during heating.

As the liquid resin to be coated, in addition to the silicone resin of the above example, epoxy resin, urethane resin,
Acrylic, polybutadiene, phenol and polyimide resins can be used.

Further, in the above-mentioned embodiment, the shape of the jig 20 is a quadrangular flat plate shape, but if the hybrid IC can be held and the shape change accompanying the temperature change described in the above-mentioned embodiment can be performed, the shape thereof is It may be a shape other than the rectangular flat plate shape.

<Effects of the Invention> That is, according to the present invention, the dried surface of the resin layer can prevent the resin from dripping onto the lead terminals, and the center of gravity of the hybrid IC can be set at a low position. It is possible to obtain a hybrid IC that is advantageous in vibration resistance without causing problems such as an increase in the number of parts and an increase in weight.

[Brief description of drawings]

1 to 9 show an embodiment of the present invention. FIG. 1 is a schematic sectional view of a batch-type curing furnace, and FIG. 2 is an example of a jig attached to a support table at a temperature lower than a predetermined temperature. Partly broken side view, FIG. 3 is a side view of the jig at a predetermined temperature or higher, FIG. 4 is a perspective view of the jig, FIG. 5 is an explanatory view showing a dip coating method, and FIG. Hybrid IC perspective view, 7th
The figure is a cross-sectional view of the mounted state of the hybrid IC, FIG. 8 is a diagram showing a heating profile, and FIG. 9 is a schematic cross-sectional view of a continuous curing furnace. 10 and 11 show a conventional example, and FIG. 10 is an explanatory view showing the dip coating method,
FIG. 11 is a sectional view of the mounted state of the hybrid IC. 11 …… Hybrid IC 12 …… Lead terminal 17 …… Resin layer 20 …… Shape memory alloy jig

Claims (1)

(57) [Claims] 1. A step of coating a liquid resin on a hybrid IC, and the hybrid IC is supported by a jig having a reversing function in which a lead terminal faces upward at a predetermined temperature or lower and a lead terminal faces downward at a predetermined temperature or higher. In this state, the process of drying the lead terminals facing upward at a predetermined temperature or lower, and heating the temperature above the predetermined temperature during drying to reverse the hybrid IC by the reversing function of the jig and dry the lead terminals downward. A hybrid IC resin coating method comprising the following steps: