JPS596512B2 - Resin package method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin packaging method for, for example, electronic components, and more specifically, the present invention relates to a resin packaging method for electronic components, and more specifically, a liquid thermosetting resin is applied to the packaged object such as the electronic component in advance before packaging by fluidized dip coating or the like. A first protective layer made of a precipitable inorganic filler is formed on the liquid resin, and then the resin is packaged using a conventional method to provide a second protective layer.This method is particularly suitable for packaging electronic components. The present invention relates to a preferred and highly reliable resin packaging system.

Electronic components include thin film resistors, ICs, hybrid ICs) transistors, diodes, etc., and are packaged to improve reliability under various environmental conditions.

In general, the current situation in this industry is that there is a shift to resin packages that can be produced at lower costs. There are various methods for producing this resin package, such as transfer molding, casting, dipping, dropping, tableting, and potting, but fluid-dip coating is a type of powder coating that is easy to mass produce and is pollution-free and resource-saving, with no material loss. It is beneficial to apply it.

The above-mentioned fluidized dip coating refers to the powder coating that is placed in a fluidized tank through a perforated plate, and the powder coating is made to flow by introducing gas from the bottom of the perforated plate. A coating film is formed on the surface by dipping the object heated above the corner point, and a coating film with excellent properties is formed by post-heating. By repeating this step, a coating film with a wide range of thickness from 0.2 to 3 mm can be obtained. It is also known to package electronic components in resin using fluidized dip coating, but this resin package maintains performance for more than 200 heat cycles from -40℃ to 150℃ and has excellent water resistance. That was impossible. On the other hand, it is also known to protect circuit elements by applying silicone rubber to the surface of the packaged object before resin packaging, but the silicone rubber has poor adhesion with packaging resins such as epoxy resin. As a result, cracks often occur during the severe heat cycle tests mentioned above.

This invention was made to eliminate the above-mentioned drawbacks, and provides a package system that is resistant to heat cycles.

The present invention is characterized in that a first resin protective layer is formed on the surface of the packaged object, and the first resin protective layer has a higher inorganic filler concentration and a lower coefficient of thermal expansion as it gets closer to the surface, and the first resin protective layer is formed to surround the first protective layer. The second resin protective layer is provided in such a manner that the second resin protective layer is formed as shown in FIG.

The first protective layer can be formed, for example, by applying a thermosetting resin containing a precipitable inorganic filler to the desired surface of the packaged object and precipitating the filler, or by heating. A second method is preferably used, in which a curable resin is applied to the surface of the packaged object, and then a filler that can be precipitated by the resin is sprinkled onto the coating film and allowed to precipitate into the coating film.

The liquid thermosetting resin used for the first protective layer is not particularly limited, and examples thereof include epoxy resin, polyester resin, polyurethane resin, and the like.

These may be either room temperature curing type or heat curing type. The lower the viscosity of these resins during curing, the more favorable the precipitation of the inorganic filler, and the higher the glass transition temperature (hereinafter abbreviated as T) of the thermosetting resin, the higher the moisture resistance If protection of the element is important, the lower the Tg, the more advantageous it is.

Suitable examples of the inorganic filler used in the present invention include alumina, glass silica, quartz, calcium carbonate, and mica.

In addition to the above, any fillers commonly used as fillers can be used. Note that the thermosetting resin and filler used in the first protective layer preferably contain less ionic impurities when it is required to prevent electrolytic corrosion due to water absorption and moisture absorption. When forming the first protective layer by the above first method, the particle size of the inorganic filler is preferably in the particle size range of 30 to 400 mesh, and the inorganic filler is preferably filled into the thermosetting resin and mixed with defossulation. It is important to.

Further, the amount of the inorganic filler blended is preferably 10 to 80 wt%, preferably 30 to 60 wt%; if it is less than this, the effect of the present invention will be reduced, and if it is more than this, it will become impossible to fill it. To carry out the first method, the thermosetting resin and the inorganic powder are mixed in a conventional manner, and then thoroughly stirred to prevent the filler in the thermosetting resin from settling. It is necessary to apply it to the designated area. The precipitable filler in the applied resin settles on the packaged object, on the element in the case of an electronic component, and a resin layer with a high filler concentration and a small coefficient of thermal expansion is formed near the element. A layer with a high resin content is formed on the surface layer of the coating film. Note that it is preferable that the filler is cured or semi-cured in a well-precipitated state. In addition, when performing the above coating, the thickness is 0.2 m.
It is preferable that the thickness be at least m, and if it is thinner than this, the effect of the present invention will be reduced.

Furthermore, the precipitation of the filler can easily be carried out during curing. On the other hand, in order to form the first protective layer by the second method, the coating thickness of the thermosetting resin should be 0.2 to 0.2 to 0.2 to 0.2 to cover the electronic component if the object to be packaged is an electronic component. 1 mTL is good.

Note that the coating method is not particularly limited, as long as a resin film is formed. In addition, the particle size of the inorganic filler is 10 to 15
One with 0 mesh is preferably used. If the particle size is larger than the above range, the finished shape of electronic components will become non-uniform and the heat cycle resistance will not improve. Moreover, if it is smaller than this, it will not settle in the liquid thermosetting resin, making it impossible to achieve high filling. The inorganic filler is filled in an amount such that the inorganic filler is exposed on the liquid thermosetting resin film. If the inorganic filler is heated in advance, it will quickly settle into the thermosetting resin, resulting in good workability. The first protective film is formed by introducing the inorganic filler into the thermosetting resin coating as described above, allowing it to settle, and then curing or semi-curing the resin. After forming the first protective layer as described above, the resin package method of the present invention can be easily implemented by forming a second protective layer using a known conventional technique so as to surround the first protective layer. Obtainable.

The present invention will be described in more detail with reference to Examples below.
Example 1 Quartz powder 1509 with a particle size of 40-150 mesh was added to a mixture of Epicote 815 (Ciel Co., Ltd., trade name) 1009 and Epomate BOO2 (Mai no Motosha Co., Ltd., trade name) 509, and the mixture was devacuolated using a Raikai machine. Then, a resin liquid used for the first protective layer was prepared.

Next, a hybrid IC consisting of elements such as a film resistor, a semiconductor chip, and a capacitor chip formed on an alumina substrate is placed horizontally, and the resin liquid is applied to the surface of the element with a brush to a thickness of 0.6 mm. When the resin was left to stand for a while, the resin was cured, and the density of the quartz powder in the cured resin was higher as it was closer to the element surface. Next, fluid dip coating was applied to this substrate using an epoxy powder bowl 256 (manufactured by Somar Kogyo Co., Ltd.) using a known conventional technique to form a coating film with a thickness of about 1 mm (
A second protective layer) was formed. For comparison, a hybrid IC without the first protective layer was similarly fluid-dip coated.

-40°C to 150°C for each of the 10 resin packaged hybrid ICs thus obtained.
As a result of a heat cycle test, 7 out of 10 devices without the first protective layer developed cracks within one cycle, and the 3 devices without cracks were fatally defective due to changes in the characteristics of the element. .

On the other hand, the hybrid IC according to this invention has 200
Even after cycling, the device remained in good condition with no cracks or changes in device characteristics. Example 2 Two-component polyurethane resin made of Polysyn/Borite (Nippon Zeon K.K.) was applied to a thickness of about 0.4 mm on the elements of a hybrid IC consisting of a capacitor IC, diode, thin film resistor, and conductor formed on the surface of alumina porcelain. 30 to 60 mesh of quartz powder, which had been previously heated to 8°C, was sprinkled on the polyurethane resin film to a thickness such that quartz was exposed on the polyurethane resin film.

The sprinkled quartz settled on top of the element, creating a resin layer of polyurethane and quartz. The thickness was approximately 0.8 mm. When this was left at room temperature for 2 hours, the polyurethane was cured. This hybrid IC was fluid-dip coated with epoxy powder F256 (manufactured by Somar Kogyo Co., Ltd.) in the same manner as in Example 1 to form a coating film with a thickness of about 0.5 mm. For comparison, the same untreated hybrid IC was made with epoxy powder F256 to a thickness of about 0.5 mm and 1.3 m! A hybrid IC coated with thick fluidized dip coating was manufactured. As a result of preparing 10 resin package products each made as described above and conducting a heat cycle test from -4'C to 150°C, the hybrid IC of the present invention exhibited no cracking and no electrical characteristics even after 200 cycles. Although there were no defects,
Both the approximately 0.5 mm package product and the 1.3 mm package product that were not subjected to the treatment of the present invention cracked or had poor electrical characteristics after 10 cycles or less. As is clear from the above results, the package product according to the method of the present invention was particularly resistant to heat cycles and had good performance.

Note that, of course, the method is not limited to the first and second methods, but all of these methods are simple and suitable for mass production and automation, and are also inexpensive.

Furthermore, in the case of electronic components such as hybrid ICs, it is sufficient for the first protective layer to cover the parts of the elements formed on the substrate, but it is of course possible to provide the first protective layer over the entire surface including the back surface. No problem.

By the way, in the above explanation, the present invention was mainly applied to resin packages for electronic parts, but it goes without saying that the present invention is not limited to this, and can also be used for packages for other articles such as precision machine parts. do not have.

As explained above, according to the present invention, it is possible to obtain a package product that is pollution-free, eliminates material loss, and is particularly resistant to cold and heat heat cycles. Unlike the filler that is dispersed evenly in the layer, the closer it gets to the surface of the package, the higher the filler concentration, in other words, the lower the coefficient of thermal expansion. This has the advantage of being able to reliably prevent cracking, especially on the side of the packaged cage.

Claims (1)

[Scope of Claims] 1. A first resin protective layer formed on the surface of the object to be packaged, the concentration of which is higher in inorganic filler as it approaches the surface, and a second resin protective layer formed to surround the first protective layer. A resin packaging method characterized by a resin protective layer. 2. The resin packaging method according to claim 1, wherein the object to be packaged is an electronic component. 3. The resin packaging method according to claim 2, wherein the electronic component comprises a substrate and a circuit element formed on the substrate.