JPS6088491A - Dimensional stability of metal foil-lined circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for improving the dimensional stability of gold Ii1 foil-clad laminates, which achieves improved dimensional stability in a significantly shorter time than conventional methods. It is possible.

One or more sheets of prepreg made by impregnating and drying various resins on various reinforcing base materials such as paper, glass cloth, glass non-woven cloth, and 11AI, iron, aluminum, other metals or alloys on one or both sides. A metal foil-clad laminate is manufactured by laminating and molding metal foils. Using this metal foil-clad laminate, a printed wiring board is usually manufactured by an etching method in step C), and in this process, heating and cooling are repeated. During such printed wiring board processing steps, the dimensions of the metal foil-clad laminate change, resulting in a problem that the positional accuracy of the pattern deteriorates.

This phenomenon is called the dimensional stability of metal foil-clad laminates. In order to improve dimensional stability, various methods are being researched and developed, such as using specific reinforcing base materials, devising impregnating resin compositions, and improving laminated molding methods. has improved considerably. However, even this may still be insufficient, and in such cases, a type of annealing method that has been practiced for a long time as a well-known and commonly used method is used to further improve the dimensional stability. The annealing method involves gradually heating the metal foil-clad laminate to a temperature slightly higher than the glass transition temperature of the base material impregnated resin, keeping it at this temperature for 2 to 4 hours, and then cooling it rapidly. After the metal foil-clad laminate is heated and cured in a laminate molding machine, it is once cooled to below the glass transition temperature of the base material impregnated resin, and then the base material impregnated resin is heated again with the press pressure reduced or substantially released. There is a method of raising the temperature to a temperature slightly higher than the glass transition temperature and gradually cooling it to room temperature.

7 Ni-Ring's method is extremely effective, but
The disadvantage is that it takes a long time.

As a result of intensive research into a new method for measuring necessary and sufficient dimensional stability in a short period of time, the present invention has revealed that heating for dimensional stabilization of metal foil-clad laminates does not necessarily require the entire metal foil-clad laminate to be impregnated. There is no need to heat the metal foil and the insulating layer adjacent to the metal foil to a temperature higher than the glass transition temperature of the impregnated resin.
Therefore, it was discovered and completed that the heating time can be extremely short, and furthermore, there is no need to particularly control cooling, such as gradual cooling.

That is, the present invention provides a metal foil-clad laminate that is laminated and formed through a heating/pressure process and a cooling process, such that the temperature of the metal foil of the laminate is equal to or higher than the glass transition temperature of the metal foil adhesive resin layer. This is a dimensional stabilization method for metal foil-clad laminates, which is characterized by heating for a short time and then cooling to room temperature.A preferred embodiment of heating is to heat the metal foil-clad laminates to This is done by sandwiching it between planar heating elements heated to a temperature higher than the glass transition temperature of the metal foil adhesive resin layer, or by passing it between heated rolls heated to a temperature higher than the glass transition temperature of the metal foil adhesive resin layer. This is due to a number of reasons.

The method of the present invention is as described above, and the effect thereof is equivalent to that of the annealing method, as demonstrated by the examples. Such a short addition! C. It is a completely new discovery that dimensional stability can be achieved on a par with conventional annealing by rapid cooling such as natural cooling or air cooling. The reason for this is not clear, but the factors that have traditionally been assumed to affect the dimensional stability of metal foil-clad laminates are: ■ Residual stress due to lamination molding ■ Curing shrinkage due to heating, current lamination molding Regarding laminates manufactured by this technology, ■ has an extremely large effect, and
The residual stress was concentrated between the metal foil and the insulating layer, which were conventionally extremely thin and could be ignored.
(2) It is reasonable to assume that the particles were extremely small in the layered molding technology that includes the current method of selecting particles.

The present invention will be explained below.

The laminate of the present invention is a normal metal foil-clad laminate, and may have any thickness, base material, impregnated resin, and other factors.

Compared to the conventional annealing method, the heating method of the present invention
It is characterized by the fact that the processing time is significantly reduced, and as mentioned above, by heating the metal foil to a temperature higher than the glass transition temperature of the metal foil adhesive resin layer, it is possible to contact the metal foil.・The processing means and processing time (
(short time), cooling method, etc. are not particularly limited.

However, from the viewpoint of improving productivity, it is desirable to complete the treatment in a shorter time, and a heating time of several to several tens of seconds is sufficient to achieve the purpose. In addition, the heating method is to sandwich the sheet between sheet heating elements heated to a temperature higher than the glass transition temperature of the metal foil adhesive resin layer of the metal foil clad laminate, or to heat the metal foil laminate to a temperature higher than the glass transition temperature of the metal foil adhesive resin layer. It is preferable that the desired temperature be achieved more uniformly and in a shorter time over the entire surface of the metal foil clad laminate by passing it between heated rolls.

Here, the temperature of the planar heating element or the roll is appropriately selected from a temperature higher than the glass transition temperature of the metal foil adhesive resin layer by 10'C or more, preferably 20''C or more, to usually 300C or less.

It should be noted that it is not preferable to apply pressure for heating heat conduction, and the contact pressure is used to ensure good heat conduction.

Also, after heating, it is taken out and cooled, but no special means is required for this either, and any method such as simply leaving it alone or cooling it with an electric fan or the like may be used.

As described above, according to the method of the present invention, dimensional stability equivalent to that of the conventional annealing method can be achieved in less than one-hundredth of the processing time of the conventional method, and its practicality is extremely high. be.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example-1 JIS GIE41i type copper clad laminate 1.6 18/
18. Using a sample with dimensions of 500 am x 500 am, the sample was sandwiched between small press heating plates with a heating chamber temperature of 160°C, heat treated at a gauge pressure of Q kg/ct for a period of 5 seconds to 1 hour, and then taken out. It was left to cool.

Table 1 shows the results of measuring the dimensional stability of each sample.

Comparative Examples 1 and 2 The dimensional stability was measured for the same samples as in Example 1 without treatment, and for those that were heated in a hot air dryer at 140° C. for 2 hours and left to cool. The results are shown in Table 1.

Example-2 JIS GIEdF type copper clad laminate o, a mi+
18/ 18, using the dimensions 500 mackerel x 500 dragon as a sample,
! ! ) The sample was sandwiched between small press heating discs with a disc temperature of 160°C and heated at a gauge pressure of Q kg/aδ for a period of 5 seconds to 1 hour.The sample was taken out and allowed to cool.

The dimensional stability of this sample was measured and the results are shown in Table 1. Comparative Examples 3 and 4 A sample similar to Example 2 was untreated and heated in a hot air dryer at 140°C for 2 hours. After that, the dimensional stability of each of the samples was measured after being left to cool. The results are shown in Table 1.

The dimensional stability test method was as described below.

■Drill holes of 1 length φ at approximately 400 ms intervals in the square part of a square double-sided copper-clad laminate of 500 am After removing the copper foil of the sample by etching, 170'c, 30
fb). After cooling, measure the distance between the holes with a coordinate measuring device.

■The dimensional change rate was calculated using the following formula.

-a Dimensional change rate ---------x io.

Table 1

Claims (1)

[Claims] 1. A metal foil-clad laminate that has been laminated and formed through a heating/pressure process and a cooling process is heated for a short time so that the temperature of the metal foil of the laminate becomes equal to or higher than the glass transition temperature of the metal foil adhesive resin layer. 1
Method 2 for stabilizing copper-clad laminates, which involves heating the metal foil-clad laminate and then cooling it to room temperature. Claim 1: The method is carried out by sandwiching between planar heating elements heated to a temperature higher than the transition temperature, or by passing between ripening rolls heated to a temperature higher than the glass transition temperature of the metal foil adhesive resin layer.
Method described in section