JPH0367618B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a laminate used as a substrate for a printed wiring board, and a method for manufacturing the same. [Background technology] Conventionally, laminates have been produced by impregnating a long base material such as glass cloth or paper with thermosetting resin varnish and drying it to create a prepreg, and then cutting this prepreg to a predetermined size. Later, it is manufactured by stacking multiple sheets of prepreg and metal foil, and heating and pressing between hot platens. However, this forming method is a so-called batch method and cannot produce laminates continuously, resulting in extremely poor production efficiency. Therefore, recently, a construction method that allows the continuous production of laminates without pressurization is becoming popular. This method involves impregnating a long base material with thermosetting resin varnish, sending multiple sheets of the base material and stacking them, then sending a long metal foil, layering them, and sending them one after another to a heat curing furnace. The thermosetting resin is then heated and cured to enable continuous production of laminates. However, in such a continuous construction method, problems arise due to the fact that pressurization is not involved. In other words, in conventional construction methods that involve pressurization, thermosetting resin is densely filled into the base material due to pressure, but in continuous construction methods that do not involve pressurization, thermosetting resin is filled in densely. It is difficult to fill the base material,
The base material will be filled in a rough state. In the case of laminates in which such thermosetting resin is not densely filled into the base material, moisture is easily absorbed into the laminate, resulting in the problem that heat resistance (PCT characteristics) decreases after moisture absorption. It is what it is. [Object of the invention] The present invention has been made in view of the above points, and can improve the heat resistance after moisture absorption of a laminate obtained by a construction method that does not involve pressurization, and can also prevent warping and deformation. The purpose is to prevent a decrease in reliability against thermal shock. [Disclosure of the Invention] The laminate according to the present invention is a laminate formed by laminating a plurality of substrates 1 impregnated with a thermosetting resin by heating under no pressure. The surface of the substrate 4 on which the material 1 is laminated has a thickness of 20 mm.
It is characterized in that a resin layer 5 of ~150 μm is formed, and the method for manufacturing a laminate according to the present invention includes a base material 1 impregnated with a thermosetting resin.
When manufacturing a laminate by stacking a plurality of sheets and heating them under no pressure to produce a laminate, the thermosetting resin 3 is applied to the outer surface of the base material 1, which is the outermost layer, and then the above-mentioned By heating under no pressure, the surface of the substrate 4 on which the base material 1 is laminated has a thickness of 20~20 mm.
The present invention is characterized in that a resin layer 5 of 150 μm is formed, and the present invention will be explained in detail below. A long piece of glass cloth or paper is used as the base material 1. First, the base material 1 is continuously rolled out from a roll and immersed in an impregnating bath, so that the base material 1 is coated with liquid. Impregnate with thermosetting resin. In the method of the present invention that does not involve pressurization, the thermosetting resin is generally an unsaturated polyester that does not emit evaporated components such as condensed water during curing. The plurality of substrates 1 impregnated with thermosetting resin in this way are continuously fed and passed through a squeeze roll 6 as shown in Fig. 1 to squeeze out excess thermosetting resin and adjust the thickness. can be overlapped while doing so. The superimposed base materials 1 are then sent to a laminating roll 7, and the long metal foils 2, 2 such as copper foils that are unwound from the rolls are rolled into the outermost layer base material 1,
The same type of thermosetting resin 3 as above is applied to the outer surface of the outermost base material 1, 1 before being sent to the laminating roll 7. The thermosetting resin 3 can be applied by applying the thermosetting resin 3 filled in the vat 8 to the outer surface of the base material 1 using the application roller 9. At this time, the overall thickness will increase due to the application of the thermosetting resin 3, but this increase in thickness will be absorbed by the thickness adjustment using the squeeze roll 6, and the laminate will have the same thickness as before. can be manufactured. Then, as described above, the laminate in which the plurality of base materials 1 and metal foils 2 are stacked is placed in a heat curing furnace.
The thermosetting resin is heated and cured in the heat curing furnace 10, and the plurality of base materials 1, 1... and metal foils 2, 2 are laminated together with the thermosetting resin. Ru. This laminate continuously coming out of the heat curing furnace 10 is cut into predetermined dimensions by a cutting machine 11 to obtain a metal-clad laminate that will become a substrate for a printed wiring board. Laminate A thus obtained
In this case, resin layers 5, 5 made of thermosetting resin 3 are formed on the outer surface of a substrate 4 on which a plurality of base materials 1, 1... are laminated as shown in FIGS. 2 and 3. The metal foil 2 is then bonded to the substrate 4 via this resin layer 5. The resin layer 5 prevents or reduces moisture absorption into the laminate A and improves heat resistance (PCT characteristics) after moisture absorption, and the thickness of the resin layer 5 is set to 20 to 150 μm. be done.
If the thickness is less than 20 μm, the prevention of moisture absorption will not be sufficient and the improvement of PCT properties will not be sufficient.
Moreover, if the thickness exceeds 150 μm, the laminate A will be greatly warped and its reliability against thermal shock will decrease, so the thickness needs to be set to 20 to 150 μm. Figure 4 shows another method of manufacturing a laminate, in which the metal foil 2 is continuously unrolled.
The metal foil 2 is passed through a drying oven 11 to dry the thermosetting resin 3, and then the laminate is manufactured in the same manner as in FIG. , a resin layer 5 is formed of a thermosetting resin 3 applied to the metal foil 2. The invention will now be illustrated by examples. Examples 1 to 3, Comparative Examples 1 and 2 As a thermosetting resin composition, 100 parts by weight of unsaturated polyester (Takeda Polymer 6320F),
A mixture of 1 part by weight of an initiator (benzoyl peroxide; BPO) and 20 parts by weight of a filler (hydrated alumina) was used, and glass cloth and glass paper were used as base materials, and copper foil with a thickness of 18 μm was used. Using the method shown in Figure 1, the plate thickness is
A 1.60mm laminate was produced. The maximum temperature of the heat curing furnace was 160°C and the minimum temperature was 60°C. Here, the one in which the thickness of the resin layer is set to 28 μm is referred to as Example 1, and the one in which the thickness of the resin layer is set to 28 μm is referred to as Example 2.
The 133 μm sample was used as Example 3, the 17 μm sample was used as Comparative Example 1, and the 152 μm sample was used as Comparative Example 2, and the PCT characteristics, warping deformation, and reliability of these samples were measured. The results are shown in the table below. In the following table,
In the PCT test, a 50 x 50 mm test piece with the copper foil removed is treated in saturated steam at 133℃ (2Kg/cm ² ) for a specified period of time, and after cooling, it is immersed in a solder bath at 260℃ for 20 seconds. This was performed by observing whether blistering occurred between the base materials, and evaluation was made based on the minimum treatment time in saturated steam when blistering occurred. The warpage was measured by supporting three ends of a 1×1 m sample and measuring the lifting dimension of the most lifting part of the other point. Furthermore, reliability tests were conducted using a thermal shock test, in which the sample was immersed in oil at 260°C for 10 seconds.
Next, one cycle consists of immersing the circuit in water at room temperature for 10 seconds and then dipping it in trichlorethylene at room temperature for 10 seconds, and measuring the number of cycles until disconnection occurs in the circuit formed by etching the copper foil. It was done by

[Table] As a result of the previous table, the thickness of the resin layer is 28μm, 67μm,
It is confirmed that the samples of Examples 1, 2, and 3 having a diameter of 133 μm have excellent post-moisture heat resistance (PCT) and no large warpage. On the other hand, Comparative Example 1 with a resin layer thickness of 17 μm has a problem with PCT, and Comparative Example 2 with a resin layer thickness of 152 μm causes large warpage and low reliability against thermal shock. It is. [Effects of the Invention] As described above, in the present invention, the resin layer with a thickness of 20 to 150 μm formed on the surface of the substrate provides
The resin layer can prevent moisture from being absorbed into the laminate and improve heat resistance after absorption, without causing large warpage or deterioration of reliability against thermal shock. .

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus used in one method of the present invention, FIG. 2 is an enlarged sectional view of a part of the laminate in the present invention, and FIG. 3 is an enlarged exploded view of a part of the same laminate. FIG. 4 is a schematic diagram of an apparatus used in another method of the same. 1 is a base material, 2 is a metal foil, 3 is a thermosetting resin, 4
5 is a substrate, and 5 is a resin layer.

Claims (1)

[Scope of Claims] 1. A laminate formed by laminating a plurality of base materials impregnated with a thermosetting resin by heating under no pressure, wherein the base material is formed on the surface of the laminated substrate. A laminate comprising a resin layer having a thickness of 20 to 150 μm. 2. When producing a laminate by stacking a plurality of base materials impregnated with thermosetting resin and laminating them by heating them under no pressure, heat is applied to the outer surface of the base material that is the outermost layer. A method for manufacturing a laminate, which comprises applying the curable resin and then heating under no pressure as described above to form a resin layer with a thickness of 20 to 150 μm on the surface of the substrate on which the base material is laminated. .