JP2001261862A - Preparation process of prepreg, prepreg, metal-laminated laminate and printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a preparation process of a prepreg which has a small residual strain and a small difference between the attached amounts of the resin of one side of a fiber base-material and the other, and also to provide a prepreg prepared by this process and, a metal-laminated laminate and a printed circuit-board each of which is made of this prepreg and is excellent in surface smoothness, thickness accuracy and warpage property. SOLUTION: This prepreg preparation process contains a coating process in which a thermosetting resin varnish is impregnated into a fiber base-material and a drying process in which the solvent of the thermosetting resin varnish impregnated into a fiber base material is evaporated and the resin is half-cured. The drying process is carried out in a horizontal drying oven in which the temperature of the drying oven is not higher than the softening point of the resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a prepreg, a prepreg, a metal-clad laminate, and a printed wiring board.

[0002]

2. Description of the Related Art In general, a prepreg used for a printed wiring board is prepared by impregnating a glass woven fabric with a thermosetting resin varnish obtained by diluting a thermosetting resin with an organic solvent, and then evaporating the solvent in a drying oven. It is manufactured by curing a curable resin to a B-stage state. The coating step and the drying step are a series of flows in a coating machine, in which a band-shaped glass woven cloth is impregnated with a thermosetting resin varnish, and the impregnated glass woven cloth is dried in a drying furnace. .

[0003] In the coating step of impregnating a glass woven fabric with a thermosetting resin varnish, the glass woven fabric is immersed in the thermosetting resin varnish, and then passed through a gap between squeeze rolls to form the thermosetting resin varnish. Weighing.

[0004] In the drying step of volatilizing the solvent and curing the resin, in the case of a glass woven fabric, a vertical drying oven is generally used, and a conveyed substrate is impregnated with a thermosetting resin varnish. After passing vertically through the gap between the squeeze rolls, it is generally performed that the drawer rolls at the outlet of the drying furnace are pulled vertically in the vertical drying furnace to move and harden the resin to the B-stage state. ing.

However, when drying the glass woven fabric impregnated with the thermosetting resin varnish in the above-described vertical drying oven,
It is necessary to move the glass woven fabric upward, and a large tension is required to move the glass woven fabric. That is, in the vertical drying oven, tension is required to move the glass woven fabric upward against the gravity, and the tension is applied to the glass woven fabric by the drawer roll provided at the outlet of the vertical drying oven. I have. Since the resin is cured in a state where the tension is applied, the tension is distorted and remains on the prepreg.

When a metal-clad laminate is manufactured using a prepreg having this residual strain, the residual strain has an adverse effect, and there is a problem that the dimensional stability and warpage characteristics of the metal-clad laminate are reduced. Further, the same problem occurs even when this prepreg is used as a prepreg for multilayer bonding.

When a metal-clad laminate is manufactured using the prepreg having the residual strain, the residual strain has an adverse effect, and there is a problem that the dimensional stability and warpage characteristics of the metal-clad laminate are reduced. Further, the same problem occurs even when this prepreg is used as a prepreg for multilayer bonding.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is directed to a method of manufacturing a prepreg having a small residual strain, a prepreg obtained by the method, and a high dimensional stability using the prepreg. It is intended to provide a metal-clad laminate and a printed wiring board.

[0009]

The present invention relates to the following. 1. In the prepreg manufacturing method including a coating step of impregnating the thermosetting resin varnish on the fiber base material and a drying step of semi-curing the resin by volatilizing the solvent of the thermosetting resin varnish impregnated on the fiber base material. A method for producing a prepreg, wherein the step is performed using a horizontal drying furnace in which the drying furnace inlet temperature is lower than the softening point of the resin. 2. In the prepreg manufacturing method including a coating step of impregnating the thermosetting resin varnish on the fiber base material and a drying step of semi-curing the resin by volatilizing the solvent of the thermosetting resin varnish impregnated on the fiber base material. A process for producing a prepreg, wherein the step is carried out by moving the fiber base material impregnated with the thermosetting resin varnish in the horizontal direction, and heating the resin to a temperature lower than the softening point of the resin at the beginning of the drying step. 3. Item 3. The method for producing a prepreg according to Item 1 or 2, wherein the fibrous base material is a strip. 4. A prepreg produced by the method according to any one of Items 1 to 3. 5. Item 5. A metal-clad laminate obtained by laminating a metal foil on one or both sides of the prepreg or the laminate thereof according to Item 4, and molding by heating and pressing. 6. Item 7. A printed wiring board obtained by subjecting the metal-clad laminate according to Item 6 to circuit processing.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, in the drying step, the fiber base material impregnated with the thermosetting resin varnish is moved in the horizontal direction. Therefore, warpage or dimensional change of a metal-clad laminate or printed wiring board manufactured using the prepreg obtained according to the present invention can be reduced. In the present invention, the tensile force in the drying step is particularly preferably adjusted to be 3.0 N / cm or less, and the metal-clad laminate manufactured using the prepreg obtained thereby or Warpage or dimensional change of the printed wiring board can be reduced. More preferably, the above-mentioned tensile force is adjusted to be 2.5 N / cm or less. In the present invention, in the drying step,
It is particularly preferable that the fiber base material impregnated with the thermosetting resin varnish is moved in a drying furnace and dried. As the above-mentioned fiber base material, it is preferable to use a band-like material from the viewpoint of ease of handling.

The length of the drying oven varies depending on the moving speed of the fiber base material impregnated with the thermosetting resin, the temperature of the drying oven, and the like.
The thermosetting resin is adjusted so as to be in a semi-cured state, particularly a B-stage state, when passing therethrough.

The temperature at the beginning of the drying step or at the entrance to the drying oven is below the softening point of the resin. Further, considering the volatilization of the solvent and the temperature stability, the temperature is preferably 50 ° C. or higher. At a temperature lower than the softening point temperature, it is preferable to retain the fiber base material impregnated with the thermosetting resin varnish so that the solvent can be sufficiently volatilized and removed. Seconds is enough. The solvent used for the thermosetting resin varnish is preferably a volatile solvent suitable for this purpose. The temperature in the drying step or the temperature in the drying furnace is preferably a temperature not lower than the softening temperature and not higher than 200 ° C, particularly preferably a temperature of 150 to 200 ° C. The drying of the fiber base material impregnated with the thermosetting resin is performed at this temperature. It is preferable that the exposure is performed under an atmosphere for 1 to 15 minutes.

[0013] In the drying step, a feed roll located before the entrance of the drying step or drying oven (which may be generally known as a horizontal drying oven)] and a feed roll located near the exit of the drying step or the drying oven. It is preferable to move the fiber base material in the drying step or in the drying direction in the horizontal direction using the drawer roll. For this purpose, a special feed roll may be provided, but a squeeze roll may perform this function. As for the drawer roll, a drawer roll may be specially provided for this purpose, and the take-up roll may perform this function.

The rotation speed of the feed roll and the rotation speed of the drawer roll are adjusted so that the tensile force applied to the fiber base material impregnated with the thermosetting resin in the drying furnace can be eliminated or reduced. Thereby, the tension applied to the fiber base material can be reduced, so that the residual strain acting on the fiber base material can be reduced. More specifically, the rotation speed of the feed roll is 95 to 1 of the rotation speed of the pull-out roll.
It is preferably set to 05%. Since the feed roll (especially when a squeeze roll is used as the feed roll) slides with the varnish, the rotation speed of the feed roll is particularly preferably 100 to 105% of the rotation speed of the drawer roll. It is particularly preferable that the rotation speed of the drawer roll and the rotation speed of the feed roll are adjusted so that the tensile force applied to the fiber base material impregnated with the thermosetting resin varnish is 3.0 N / cm or less.

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of an example of an apparatus used for producing the prepreg of the present invention. Pre-preg horizontal manufacturing equipment 1
Are impregnation tank 3 containing thermosetting resin varnish 2, impregnation tank 3
And a squeeze roll 5 also serving as a feed roll, a horizontal drying furnace 6, and a drawer roll 7.
The impregnated tank 3 impregnates the thermosetting resin varnish 2 with the conveyed fiber base material 8 such as a glass woven cloth or the like in the impregnation tank 3, and then passes through the gap of the squeeze roll 5.
It is moved horizontally in the horizontal drying furnace 6 and pulled out by the drawer roll 7. In the horizontal drying furnace 6, the thermosetting resin is
It is cured to a stage state to produce a prepreg. The prepreg coming out of the horizontal drying furnace 6 is supplied to a drawer roll 7.
Or after being passed through a drawer roll 7, it is wound on a take-up roll, or is cut into a predetermined size after passing through the drawer roll 7. In the horizontal drying furnace 6, in order to support the fiber base material 8, it is preferable to blow up gas such as air from below. In this case, gas such as air is also blown from above so that the base material is stable without waving. It is preferable to spray. In the horizontal drying furnace 6, a roll or the like may be used to support the fiber base material. The gas in the drying oven preferably has a wind speed of 5 m / min to 15 m / min in order to support the fiber base material.

The fiber substrate of the present invention is a woven or non-woven fabric such as glass fiber and organic fiber. Glass woven fabric is most preferred. When the fiber base material having a resin holding force is imparted to the fiber base material and the thermosetting resin-impregnated fiber base material moves in the drying oven, the thermosetting resin varnish attached to the fiber base material is gravity-adjusted. Since it shifts to the lower side, the correlation between the air permeability y (cc / cm 2 / sec) and the thickness x (μm) of the fiber base material (1 )formula

It is preferable that the following formula is satisfied: y ≦ −0.1x + 25 (1) The thickness of the fiber substrate depends on the material, but is preferably 50 to 250 μm.
In the present invention, the air permeability is measured based on JIS R 3420. Therefore, a metal-clad laminate or a printed wiring board manufactured using this prepreg is particularly small in warpage or dimensional change. The same effect can be obtained when the prepreg is used as a prepreg for multilayer bonding.

The thermosetting resin used in the present invention includes epoxy resin, phenol resin, polyimide resin,
A polyester resin, a cyanate ester resin, a resin having a benzoxazine ring, and a thermosetting resin having a triazine ring can be used, and an epoxy resin is particularly preferable in terms of heat resistance and water absorption.

As the epoxy resin, a bifunctional or higher functional epoxy resin is used. For example, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, alicyclic epoxy resin, phenol novolak epoxy resin, cresol novolak epoxy resin, bisphenol A novolak epoxy resin, polyfunctional phenol Glycidyl ether products, diglycidyl ether products of polyfunctional alcohols, hydrogenated products thereof, and the like can be given. These are usually used alone, but several types can be used in combination.

The curing agent is not particularly limited as long as it is used as an epoxy resin curing agent for electric insulating materials. For example, amines, phenols, acid anhydrides and the like can be used. Specific compounds are shown below. Examples of amines include diethylamine, diethylenethiamine, triethylenetetramine, diethylaminopropylamine, aminoethylpiperazine, mensendiamine, metaxylylenediamine, dicyandiamide, diaminodiphenylmethane, diaminodiphenylsulfone, methylenedianiline, and metaphenylenediamine. Can be mentioned. Examples of the phenols include bisphenol, bisphenol A, bisphenol F, phenol novolak resin, cresol novolak resin, bisphenol A novolak resin, and alkyl group-substituted products thereof. Examples of the acid anhydride include hexahydrophthalic anhydride, tetrahydrophthalic anhydride, pyromellitic anhydride, chlorendic anhydride, nadic anhydride, methylnadic anhydride, dodecynylsuccinic anhydride, phthalic anhydride, methylhexahydrophthalic anhydride, Maleic anhydride and the like can be mentioned. These are usually used alone, but several types can be used in combination.

As the epoxy resin, a novolak type epoxy resin, for example, a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, a bisphenol A novolak type epoxy resin, and the like, and as a curing agent, a novolak type phenol resin, for example, phenol novolak A combination with a resin, a cresol novolak resin, a bisphenol A novolak resin, or the like is preferable because the cured product has excellent heat resistance.

The curing agent is preferably used such that the functional group of the curing agent is blended in the range of 0.8 to 1.2 equivalents with respect to 1 equivalent of the epoxy group of the epoxy resin, and 0.85 to 1.1 equivalents. More preferably, it is blended so as to fall within the range. In both cases where the functional group of the curing agent is less than 0.8 equivalent and more than 1.2 equivalent, the glass transition temperature becomes low and moisture is easily absorbed, so that heat resistance is lowered.

A curing accelerator may be used in combination with the epoxy resin and the curing agent, if necessary. The curing accelerator is not limited as long as it is a compound having a catalytic function of accelerating an etherification reaction between an epoxy group and a phenolic hydroxyl group, and examples thereof include an alkali metal compound, an alkaline earth metal compound, an imidazole compound, and an organic phosphorus compound. , Secondary amines, tertiary amines, quaternary ammonium salts and the like. It is preferable to use imidazole in which the imino group is masked with acrylonitrile, isocyanate, melamine acrylate, or the like, since a prepreg having storage stability twice or more that of conventional prepregs can be obtained.

These curing accelerators may be used in combination of several kinds, and the compounding amount is preferably 0.01 to 5 parts by weight based on 100 parts by weight of the epoxy resin. If the amount is less than 0.01 part by weight, the accelerating effect tends to decrease, and if it exceeds 5 parts by weight, the storage stability tends to deteriorate.

Examples of the imidazole compound include imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, and 2-heptadecylimidazole. , 4,5-diphenylimidazole, 2-methylimidazoline, 2-
Phenylimidazoline, 2-undecylimidazoline,
2-heptadecylimidazoline, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl-4-methylimidazole, 2-ethylimidazoline, 2-isopropylimidazoline, 2,4-dimethylimidazoline, 2-phenyl-4- Examples of the masking agent include acrylonitrile, phenylene diisocyanate, toluidine isocyanate, naphthalene diisocyanate, methylene bisphenyl isocyanate, and melamine acrylate.

In the thermosetting resin, if necessary,
An inorganic filler such as aluminum hydroxide and clay is added. Further, if necessary, other compounds can be blended as long as the effects of the present invention are not impaired.

The thermosetting resin and other components are dissolved or dispersed in a solvent and used as a varnish. Solvents used include acetone, methyl ethyl ketone,
Ketone solvents such as methyl isobutyl ketone; aromatic hydrocarbon solvents such as toluene and xylene; ester solvents such as ethyl acetate; ether solvents such as ethylene glycol monomethyl ether; amide solvents such as N, N-dimethylacetamide , Methanol, ethanol and the like, and some of them may be used as a mixture. The solid concentration in the varnish is 50
It is preferable that the content is about 80% by weight.

The method of impregnating the fiber base material with the thermosetting resin varnish is not particularly limited, but it is preferable to pass the base resin through a tank containing the thermosetting resin varnish. At this time, the amount of resin adhered to the fiber base material is preferably such that the varnish solid content is 35 to 60% by weight based on the total amount of the varnish solid content and the base material.

The obtained prepreg is cut into a predetermined size, and then laminated singly or in an arbitrary number of layers, and a metal foil is laminated by laminating a metal foil on one or both sides thereof and heating and pressing. It can be a plate. As the conditions at this time, it is preferable that the heating temperature is 150 to 230 ° C. and the pressure is 2 to 5 MPa, and it is preferable that the heating conditions be 0.5 to 2.0 hours.

As the above-mentioned metal foil, copper foil, aluminum foil and the like are used. The thickness of the metal foil depends on the application, but is 5-100μ
m are preferably used.

The printed wiring board can be obtained by subjecting the metal foil of the metal foil-clad laminate to circuit processing. For circuit processing, for example, after forming a resist pattern on the surface of the metal foil, the unnecessary portion of the foil is removed by etching, the resist pattern is peeled off, plating is performed to conduct to the necessary through holes by a drill, and finally the resist is This can be performed by peeling the pattern. On the surface of the printed laminate thus obtained, the above-mentioned metal foil-clad laminate is further laminated under the same conditions as described above, and further processed in the same manner as above to obtain a multilayer printed wiring board. Can be. In this case, it is not always necessary to form a through hole, and a via hole may be formed, or both may be formed. Such multilayering is performed for a required number of sheets.

[0031]

[Function] When drying glass woven fabric impregnated with a thermosetting resin varnish in a horizontal drying oven, if the temperature of the drying furnace inlet is set to a temperature higher than the softening point of the resin, the resin rapidly softens, and the surface of the glass woven fabric becomes soft. Since the resin easily moves and the resin hardens in that state, there is a possibility that the resin adhesion amount varies on the front and back of the fiber base material. When a metal-clad laminate is manufactured using a prepreg having a large variation in the amount of adhered resin, there arises a problem that the surface smoothness, plate thickness accuracy, and warpage characteristics of the metal-clad laminate are reduced. The initial or horizontal drying furnace inlet temperature is kept below the softening point of the resin to suppress the decrease in the viscosity of the resin, reduce the flow of the resin on the surface of the glass woven fabric, and then cure the resin. Becomes smaller. As described above, according to the present invention, a prepreg having a small variation in the amount of adhered resin can be obtained on the front and back surfaces of the fiber base material, so that a metal-clad laminate and a printed wiring board having excellent surface smoothness, thickness accuracy and warpage characteristics can be manufactured. can do.

[0032]

Next, examples of the present invention will be described. Example 1 Brominated bisphenol A type epoxy resin (epoxy equivalent: 480, bromine content: 21.5% by weight, softening temperature: 80 ° C.)
100 parts by weight, 2.6 parts by weight of dicyandiamide and 2-
Ethyl-4-methylimidazole (0.2 part by weight) was dissolved in methyl ethyl ketone to prepare a thermosetting resin varnish having a solid content of 65% by weight. Further, a prepreg horizontal manufacturing apparatus as shown in FIG. 1 was used. The above-mentioned thermosetting resin varnish was put in an impregnation tank, and the thickness was 0.20 mm and the air permeability was 5 c.
The glass woven cloth impregnated with the thermosetting resin varnish is passed through a 1.2 m wide band-shaped glass woven cloth having a c / cm2 / sec and then the glass woven cloth impregnated with the thermosetting resin varnish. Was passed through a drying oven to produce a prepreg having a resin content of 42% by weight.

The specifications of the drying oven are as follows. Length of drying oven; 35 m Residence time of glass woven fabric impregnated with thermosetting resin varnish in drying oven: 50 seconds Temperature in drying oven: gap through which glass woven fabric impregnated with thermosetting resin varnish passes Was opened, the drying oven was divided into six rooms, and the temperature in each room was kept constant. The length of each room,
The temperatures are as follows: First room from the beginning: 4.5m, 70 ° C (entrance temperature) Second room from the beginning: 4.5m, 100 ° C Third room from the beginning: 4.5m, 140 ° C First from the fourth 5th room from the beginning: 4.5m, 180 ° C Fifth room from the beginning: 6.0m, 180 ° C 6th room from the beginning: 6.0m, 140 ° C Rotation speed of slide roll: 25m / min. Rotational speed: 25 m / min. Tensile force applied to the glass woven fabric impregnated with thermosetting resin varnish: 2.3 N / cm (immediately before the draw roll). Air was blown up, and air was blown from above so that the fiber base material was stabilized.

Example 2 A glass woven fabric having a thickness of 0.10 mm and an air permeability of 15 cc
A prepreg having a resin content of 46% by weight was produced in the same manner as in Example 1 except that a glass woven fabric of / cm2 / sec was used.

Comparative Example 1 A prepreg manufacturing apparatus using a vertical drying furnace was used as a drying furnace, and 0.10 mm and a gas permeability of 5 cc / cm 2 were used.
/ Sec, except that a glass woven fabric was used, and a prepreg having a resin content of 46% by weight was produced. The size of the vertical drying furnace in this prepreg manufacturing apparatus was 17 m in height, and the fiber base material reciprocated through a roll in the vertical drying furnace, so that a length of 34 m was present in the drying furnace. Otherwise, the apparatus was the same as the apparatus shown in FIG. However, the rotation speed of the slide roll: 25 m / min The rotation speed of the drawer roll: 0.7 m / min. In order for the fiber base material to be sent stably without flapping, the rotation speed of the drawer roll needs to be higher than the rotation speed of the slide roll. The tensile force immediately before the pull-out roll was 3.4 N / cm.

Comparative Example 2 A prepreg having a resin content of 46% by weight was produced in the same manner as in Comparative Example 1 except that a glass woven fabric having a thickness of 0.10 mm and an air permeability of 20 cc / cm ² / sec was used. The tensile force immediately before the pull-out roll was 3.4 N / cm.

Comparative Example 3 The procedure of Example 1 was repeated, except that the drying furnace inlet temperature was 150 ° C. and the temperature inside the drying furnace was maintained at 150 to 185 ° C. % Prepreg was produced.

The prepregs of Example 1, Example 2, and Comparative Examples 1 to 3 were cut to a predetermined size, and 18 μm was cut on both sides.
m of copper foil, and this material is made of stainless steel with a thickness of 1.
Insert these components into an 8 mm end plate, superimpose these components 13 times, insert between press hot plates, and apply a temperature of 185 with a multi-stage press.
Molding was performed for 85 minutes at a temperature of 4 ° C. and a pressure of 4 MPa to produce a double-sided copper-clad laminate. Circuit processing was performed on the obtained double-sided copper-clad laminate by a conventional method to produce a printed wiring board. Table 1 shows the performance of the double-sided copper-clad laminate and the printed wiring board. Table 1 shows these performances.

[0039]

[Table 1] * 1: The deviation when measuring the thickness of the double-sided copper-clad laminate at any 50 points without a 300 mm square sample. * 2: The difference between the maximum value and the minimum value when the thickness of the double-sided copper-clad laminate was measured at any 50 points without a 300 mm square sample. * 3: Mark a mark at the center of a 300 mm square sample.
This figure shows the warpage (maximum) and dimensional change of the end due to circuit processing on the printed wiring board.

The performance of the copper-clad laminates of Examples 1 and 2 and the comparative example is clear from Table 1. The performance of the copper-clad laminate of the present invention is smaller than that of the copper-clad laminates other than the present invention. It was confirmed that the change was small, and that the warpage and dimensional change during the multi-layer bonding were small.

[0041]

The prepreg produced according to the present invention is less likely to cause residual strain because the tension applied to the fiber base material during the production can be reduced. The metal-clad laminates and printed wiring boards manufactured using them have excellent surface smoothness and plate thickness accuracy,
Small warpage and dimensional change.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a prepreg horizontal manufacturing apparatus used for manufacturing a prepreg in the present invention.

[Explanation of symbols]

1 horizontal coating machine, 2 thermosetting resin varnish, 3 impregnation tank, 4 impregnation roll, 5 squeeze roll, 6 horizontal drying furnace, 7 drawer roll, 8 glass woven fabric.

Continued on the front page (72) Inventor Takashi Matsuzaki 1500 Ogawa, Shimodate-shi, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd. AJ04 AJ13 AK02 AL13

Claims (6)

[Claims] 1. A prepreg comprising a coating step of impregnating a fibrous base material with a thermosetting resin varnish and a drying step of volatilizing a solvent of the thermosetting resin varnish impregnated on the fibrous base material and semi-curing the resin. A method for producing a prepreg, wherein the drying step is performed using a horizontal drying furnace in which the drying furnace inlet temperature is lower than the softening point of the resin. 2. A prepreg comprising a coating step of impregnating a thermosetting resin varnish on a fiber base material and a drying step of volatilizing a solvent of the thermosetting resin varnish impregnated on the fiber base material and semi-curing the resin. In the production method, the drying step is performed by moving the fiber base material impregnated with the thermosetting resin varnish in the horizontal direction, and further, the drying step is heated to a temperature equal to or lower than the softening point of the resin. Method for producing prepreg. 3. The method for producing a prepreg according to claim 1, wherein the fibrous base material is a strip. 4. A prepreg produced by the method according to claim 1. 5. A metal-clad laminate obtained by laminating a metal foil on one side or both sides of the prepreg or the laminate thereof according to claim 4, and subjecting the laminate to heat and pressure molding. 6. A printed wiring board obtained by subjecting the metal-clad laminate according to claim 5 to circuit processing.