JPH02217240A - Surface mounting laminated sheet - Google Patents

Abstract

PURPOSE:To stably hold the connection of the metal foil circuit integrated with a base material layer to a mounting part even when subjected to a large temp. change and to enhance the reliability of circuit connection by integrally arranging an elastomeric resin layer having high modulus of elasticity between an outer metal foil and the base material layer to which said metal foil must be laminated. CONSTITUTION:For example, a solution prepared by dissolving an elastomeric resin composition 2 having high modulus of elasticity in a solvent is applied to the mat surface 1 (the surface on the side of a base material) of a copper foil and dried to prepare the resin applied copper foil. Usually, four epoxy resin cloths 3 are superposed and the resin applied copper foils are arranged to both front and rear surfaces thereof and the whole is held between metal plates and molded to obtain a panel. An elastomeric resin layer 4 having high modulus of elasticity is formed between the metal foil 1 and the base material 3 as a stress relieving layer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a laminate for surface mounting. More specifically, the present invention relates to a new surface mounting laminate that can improve the reliability of component-to-circuit connection against temperature changes.

(Conventional technology) Laminated boards for wiring boards used in precision equipment, electronic computers, communication equipment, etc. have been increasing in recent years with increasing demands for high-density packaging, as well as characteristics such as heat resistance, strength, and workability. , there is a strong demand for improved reliability of circuit connections. In particular, due to high-density packaging and high integration of element parts, it is required to cope with temperature changes caused by heat generation from the parts.

Conventionally, laminates for wiring boards have been made by combining the required number of resin cloth, etc., which is a base material such as glass cloth impregnated with resin, and pasting metal foil on the front and back sides to make a double-sided board, or by forming an inner layer inside the laminated board. The most common type of laminated plate is a multi-layered plate formed by interposing materials, and various improvements have been made to these laminated plates in order to address the above-mentioned problems.

For example, studies have been conducted to reduce the difference in thermal expansion between the circuit (metal foil) and the resin-impregnated base material layer due to temperature changes by using a resin with a small coefficient of thermal expansion, thereby preventing disconnection between the component and the circuit. There are some too.

(Problem to be solved by the invention) However, in conventional laminates, the thermal expansion of the base material layer is larger than that of the components, and disconnection between the components and the circuit (metal foil) during surface mounting. However, the disadvantage of easily causing problems remained unresolved.

This invention was made in view of the above-mentioned circumstances, and solves the problems regarding the reliability of circuit connections of conventional laminates. The objective is to provide a new laminate that can maintain stable connections between foil circuits and mounted components and improve the reliability of circuit connections.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a method in which an elastomer-based resin layer with a high elastic modulus is disposed between the outer metal foil and the base material layer on which it is laminated. To provide a laminate for surface mounting, which is characterized by being made of

In addition, the invention provides a method for manufacturing such a surface mounting laminate, in which an elastomer-based resin composition with a high elastic modulus is applied to the laminated surface of the outer layer metal foil, and the metal foil and the base material are heat-pressed. The present invention also provides a method characterized in that the method is characterized in that it is laminated.

In other words, the surface mount laminate of the present invention has a stress relaxation layer between the outer metal foil and the base layer, whereas in conventional laminates the outer metal foil is directly disposed on the base layer. It is characterized by interposing an elastomer resin layer with a high elastic modulus.

As the high modulus elastomer resin, one that exhibits rubber elasticity after curing can be used.

Specifically, imprene rubber, butyl rubber, butadiene rubber, nitrile rubber, chloroprene rubber, urethane rubber,
Rubber elastic elastomers such as acrylic rubber, acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylic resin, acetal resin, polyamide resin (
Examples include those made of elastomers such as nylon), polyester resin, styrene-butadiene copolymer resin, urethane resin, and Teflon resin. These may be used alone or in combination of multiple types.
Further, it may be used in combination with a resin used for forming the base material such as an epoxy resin.

The surface mounting laminate of the present invention can take various forms as long as the elastomer resin layer having the above-mentioned elastic modulus is disposed between the outer metal foil and the base material layer.
There are no particular restrictions on the type of resin used for the base material layer, the layer structure, the type of outer metal foil, etc., and materials conventionally used as molding materials for laminates can be used as appropriate.

For example, a prepreg impregnated with bisphenol type epoxy resin, polyimide resin, BT resin, or the like, or a sheet material thereof, can be appropriately combined with metal foil to form a single-sided, double-sided, or multilayer laminate.

In addition, various additives such as a flame retardant, a heat resistance imparting agent, an inorganic powder, and a reinforcing agent can be added to the resin in this case, as in conventional laminates. When using prepreg, a base material can be impregnated with a predetermined resin varnish and dried or semi-cured to obtain a B stage.

There are no particular limitations on the base material in this case, and cloth such as glass cloth, aramid cloth, polyester cloth, nylon cloth, mat-like materials, nonwoven fabrics, etc. can be used.

As for the metal foil, a wide variety of metal foils such as copper foil, aluminum foil, etc. used in ordinary laminates can be used.

As described above, regarding the surface mounting laminate of the present invention in which a high elastic modulus elastomer resin layer is disposed between the outer metal foil and the base material layer, the manufacturing method and manufacturing conditions may be adjusted as appropriate. Can be adopted.

The most preferable manufacturing method is to first apply an elastomer-based resin composition with a high elastic modulus to the laminated surface of the base material of the outer layer metal foil, and then overlay the outer layer metal foil on the base material and heat-press the laminated layer. An example of how to legalize it is given.

This method is illustrated in the steps in FIG.

That is, (a) the elastomer-based resin composition (2) is applied to the base material lamination surface of the outer layer metal foil (1) and dried. Also,
For example, this resin-coated metal foil (1) is placed on both outermost surfaces of a plurality of base materials (3) such as resin-impregnated glass cloth, and (b) these are heat-pressed using a press or the like to form a laminated layer. become

As a result, a high elastic modulus elastomer resin layer (4) serving as a stress relaxation layer is provided between the metal foil (1) and the base material (3) layer.
) is formed.

In this case, a high modulus elastomer resin composition (2)
As the material, a mixture of the above-mentioned high modulus elastomer resin and a solvent can be used. Moreover, as a method for applying the resin composition el(2) to the outer layer metal foil (1), an appropriate method such as transferring with a roll can be adopted. Of course, the temperature and pressure conditions during heat pressing are also determined as appropriate depending on the type of resin and base material used, the lamination mode, etc.

(Function) The surface mounting laminate of the present invention has a high elastic modulus elastomer resin layer interposed between the outer metal foil and the base material layer as a stress relaxation layer, so that the base material layer can be loosened by temperature changes. Even if a certain degree of thermal expansion occurs, the elastomeric resin layer with a high elastic modulus alleviates thermal stress, prevents cracks from forming in the connection between the outer layer metal foil circuit and the mounted components, and improves the reliability of the circuit connection.

(Examples) Hereinafter, the present invention will be explained in more detail by showing examples.

Example 1 (i) Carboxyl-terminated butadiene nitrile (manufactured by Ube Industries, Ltd., CTBN) dissolved in a solvent as a high modulus elastomer resin composition was placed on the matte surface (substrate side surface) of a qlA foil with a thickness of 18 μm. ) was applied by roll transfer and dried to produce resin-coated copper foil with a resin thickness of about 30 μm.

Four sheets of ordinary epoxy resin resin cloth (0,1+w glass cloth base material, resin content 43%) are stacked, and the above-mentioned resin-coated copper foil is placed on both the front and back sides, and this is sandwiched between metal plates, and molding pressure is applied. A laminate with a thickness of 0.4 mm was obtained by molding at 40 hg/aa and a temperature of 170° C. for 100 minutes.

(ii) A circuit was formed on the evaluated laminated board, a flip chip was mounted on the circuit shown in Figure 2, and a thermal cycle impact test (1 cycle = -30°C, 30 minutes - (30 minutes) → 150 °C, 3
0 minutes), the number of cycles until disconnection was measured and evaluated.

The results are shown in Table 1.

As is clear from comparison with the comparative example described below, the number of times the wire broke was 10 to 12 times higher.

It can be seen that the reliability of the connection is extremely high.

Example 2 Acrylic terminated butadiene nitrile (manufactured by Ube Industries, Ltd., ^T
A laminate was manufactured in the same manner as in Example 1 using the same method as in Example 1, and subjected to a thermal cycle impact test.

The results are shown in Table 1. As in Example 1, the connection reliability was excellent.

Example 3N4 A high modulus elastomer resin composition containing towt% of each of CTBN and ^TBN in an epoxy resin was used, a laminate was produced in the same manner as in Example 1, and a thermal cycle impact test was conducted. Ta. The results are shown in Table 1.

Example 5 A laminate was produced in the same manner as in Example 1 using a Teflon resin elastomer as a high modulus elastomer resin composition, and subjected to a thermal cycle impact test. The results are shown in Table 1.

In this case as well, the connection reliability was excellent as in each of the above examples.

Comparative Example 1 A laminate was produced in the same manner as in Example 1 without applying the high modulus elastomer resin composition to the copper foil, and subjected to a thermal cycle TS impact test. The results are also shown in Table 1.

The connection reliability is considerably lower than in the example.

Comparative Example 2 A laminate was produced in the same manner as in Example 1 without applying the high modulus elastomer resin composition to the copper foil, and a cold/hot cycle Wi-impact test was conducted. In this comparative example, polyimide resin was used as the impregnating resin for the resin cloth.

The results are shown in Table 1.

Similarly, connection reliability is low.

(Effects of the Invention) As explained in detail above, the surface mounting laminate of the present invention maintains the connection between the metal foil circuit and the component stably even under large temperature changes, and improves the component-to-circuit connection. Reliability can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 shows l! of this invention. 31 is a process cross-sectional view illustrating a laminate obtained by the method. FIG. 2 is a plan view showing the circuit used in the thermal cycle impact test. 1...Outer metal foil 2...Resin composition 3...Base material 4...Resin layer

Claims (2)

[Claims] (1) A laminate for surface mounting, characterized in that an elastomer-based resin layer with a high elastic modulus is integrated between an outer metal foil layer and a base material layer on which it is laminated. (2) Claim (1) characterized in that an elastomer-based resin composition having a high elastic modulus is applied to the laminated surface of the outer layer metal foil, and the metal foil and the base material are heated and pressed to integrate the lamination. The method for manufacturing the surface mounting laminate described above.