JP4784352B2 - Steel plate for printed circuit board - Google Patents

Description

  The present invention relates to a steel plate for a printed circuit board used as a support for a photosensitive resin plate material. The steel sheet also includes a steel sheet whose surface is plated.

  Traditionally, typographic printing has used plate materials made by corroding metals such as lead, zinc, and copper with chemicals. However, it takes time and cost to make plates, and it requires specialized technology. Then, it is the mainstream to use a photosensitive resin plate material. This photosensitive resin plate material is a photosensitive material in which a base polymer such as alcohol-soluble or water-soluble polyamide or polyvinyl alcohol SBR is mixed with a photopolymerization component, a photosensitizer, a heat stabilizer, a plasticizer, etc. on the surface of a support. After a thin and uniform coating of the photosensitive resin layer with a thickness of 0.2 mm or more is performed, the negative film is vacuum-adhered to this surface and exposed, and the unexposed part is eluted with water and dried. The exposed portion becomes the plate surface convex portion (image portion), and the elution portion becomes the plate surface concave portion (non-image portion).

  Conventionally, a relatively thick steel plate (hereinafter, this steel plate is also referred to as “printed board steel plate”) has been used for the support. Therefore, it is heavy and poor in workability.When attaching the rotary press to the plate cylinder, it is necessary to attach the curl with a carving machine in advance, and the work is complicated.There is a dedicated cutter for size adjustment. There were problems such as being required.

As a technique for solving this problem, for example, Patent Document 1 discloses a typographic photosensitive material using a steel plate having a tensile strength of 55 kgf / mm ² or more, an elongation of 10% or less, and a thickness of 0.03 to 0.12 mm as a support. Resin letterpress material is disclosed. Patent Document 2 discloses a photosensitive resin plate material using a steel plate having a tensile strength of 20 to 45 kgf / mm ² , an elongation of 10% or more, and a thickness of 0.05 to 0.13 mm as a support. According to these techniques, it is not necessary to attach a curl by a carving machine, and it is possible to obtain a printed board steel plate that is easy and light in cutting and excellent in workability.

  By the way, a steel sheet for printed circuit boards is required to have high strength and excellent flatness. Therefore, in the prior art, a thin cold-rolled steel sheet that is excellent in smoothness and thickness accuracy and satisfies the required characteristics as a printing material is used as the steel sheet, and if necessary, the surface thereof is for rust prevention. "Plating" or chemical-treated ones were used.

  The steel sheet for printed boards has been manufactured by further rolling and thinning the annealed cold-rolled steel sheet. Specifically, a hot-rolled steel sheet is cold-rolled to an intermediate thickness, and a steel sheet that has been tin-plated or galvanized for the purpose of improving lubrication or the like as needed is further cold-rolled to achieve the desired 0.03. It was a very thin steel plate (steel foil) having a thickness of ˜0.13 mm. However, the steel sheet for a printed board having a thickness of 0.13 mm or less has a problem that it is easy to bend and difficult to handle because it is thin.

Therefore, a cold-rolled steel sheet having a thickness exceeding 0.13 mm is often used as a printed board steel sheet. Such a cold-rolled steel sheet having a thickness exceeding 0.13 mm is obtained by hot rolling a low-carbon steel material, re-annealing the cold-rolled steel sheet by continuous annealing or the like, and further using a DCR mill or the like. Subsequent cold rolling is performed to obtain a product thickness, and thereafter, surface treatment such as tin plating or chrome plating is performed as necessary (see, for example, Patent Document 3).
JP-A-62-056967 JP 09-138507 A Japanese Patent Laid-Open No. 63-060591

  However, in the above manufacturing method, since the plate thickness is thin, shape control with a secondary cold rolling mill is difficult, and shape defects such as ear elongation and middle elongation are likely to occur. In addition, since the material of the secondary cold rolling is an annealed material and is soft, there is a problem that buckling streak defects such as bellows and vertical bars are likely to occur. Moreover, in this manufacturing method, since it is necessary to perform secondary cold rolling after annealing, the production efficiency was lowered and the production cost was increased. On the other hand, the steel sheet for printed circuit boards of SR material (Single Reduce material) manufactured by one cold rolling has a problem that the strength (tensile strength) is low and the fatigue strength is low. I had it.

  In order to avoid such a problem, it has been considered that a predetermined product sheet thickness is obtained by one cold rolling without including an annealing step in the middle, and the annealing step is omitted. In this method, the problems in the two-rolling method can be solved to some extent, and a steel plate having high strength and good flatness can be manufactured at low cost. However, since the steel sheet obtained by this method is in an unannealed state as cold-rolled, the elongation is close to zero (0)%.

  As a method of attaching a steel plate to a plate cylinder (drum) of a rotary press, a magnet or a bolt may be used, but in many cases, the end portion of the steel plate is folded and attached. In this case, since the steel sheet is subjected to a bending process almost similar to close contact bending, the above-described cold-rolled steel sheet is cracked in the bent portion and cannot be practically used.

  Then, the objective of this invention is providing the steel plate for printed circuit boards which is excellent in ductility (bending property) while being high intensity | strength and excellent in flatness at low cost. Specifically, the mechanical properties that the steel sheet of the present invention should have are a tensile strength TS of 500 MPa or more and a total elongation El of 2% or more.

  Inventors repeated examination in order to solve the said problem which a prior art has. As a result, low carbon steel added with an appropriate amount of P and / or Nb is used as a raw material, and this is rolled to the final sheet thickness by one cold rolling, annealed, and temper rolled, thereby causing the above-mentioned problems As a result, the present invention was completed.

That is, the present invention includes C: 0.02 to 0.09 mass %, Mn : 1.0 mass% or less, P: 0.07 to 0.15 mass% , Al: 0.031 mass% or less, N: 0.03 mass%. It is a steel sheet for a printed circuit board containing the following , the balance being a component composition composed of Fe and inevitable impurities, a tensile strength of 500 MPa or more, and a total elongation of 2% or more.

In the present invention, C: 0.02-0.09 mass% , Mn : 1.0 mass% or less, P: 0.02-0.15 mass%, Nb: 0.02-0.06 mass % , Al: 0 0.03 mass% or less, N: 0.03 mass% or less , the balance being a component composition composed of Fe and inevitable impurities, a tensile strength of 500 MPa or more, and a total elongation of 2% or more. It is.

  The steel sheet of the present invention has a plating layer on the surface thereof.

  According to the present invention, it is possible to produce a steel sheet having not only high strength and excellent flatness but also excellent ductility as compared with the prior art at low cost. Therefore, this steel plate is suitable for use as a steel plate for a printed circuit board of a photosensitive resin plate material.

An experiment that triggered the development of the present invention will be described.
C: 0.02 to 0.09 mass%, Mn: 0.50 mass%, N: 0.01 mass%, the balance being substantially made of Fe, and Nb added thereto 0.02 mass% and 0.06 mass% Steels based on a total of three types of steels, and further added with P in the range of 0.01 to 0.15 mass%, were melted in the laboratory and hot-rolled to obtain a thickness of 1. 8 mm hot-rolled sheet, pickled, cold-rolled to a thickness of 0.18 mm, recrystallized at 760 ° C. for 15 seconds, tempered and rolled 1.0%, and cooled A fire annealed plate was used. For this steel sheet, a tensile test piece in the direction parallel to the rolling direction is taken and a tensile test is conducted to measure the tensile strength TS and total elongation El, and a strip-like test piece in the C direction is taken and is subjected to tight bending (bending). R = 0t (t: thickness) was tested.

The result of the measurement is shown in FIG. From this result, it can be seen that even if Nb is not added, the tensile strength TS ≧ 500 MPa can be obtained if the steel sheet is added with 0.07 mass% or more of P. Further, it can be seen that by adding Nb, a steel sheet with 0.02 mass% or more of P can be obtained with a tensile strength TS ≧ 500 MPa. Therefore, when it adds excessively, the addition amount of P which has a bad influence on corrosion resistance can be reduced. Furthermore, all of these steel sheets showed a value of the total elongation El of 20% or more, and no cracking occurred even in close contact bending.
The present invention has been developed based on the above findings.

Next, the reason for limiting the component composition of the steel sheet for printed boards according to the present invention will be described.
C: 0.02-0.09 mass%
C is an essential component for increasing the strength of steel. In the steel plate of the present invention, it is necessary to add 0.02 mass% or more. However, if it exceeds 0.09 mass%, the strength of the steel becomes too high and the rolling load increases, making it impossible to roll to the product sheet thickness by one cold rolling, It becomes easy to cause a shape defect. Further, when C is large, the amount of precipitated carbide increases, which may cause breakage during printing. Therefore, the upper limit of C in the steel sheet of the present invention is 0.09 mass%. Preferably, C is in the range of 0.04 to 0.07 mass%.

P: 0.02-0.15 mass% or 0.07-0.15 mass%
P is a component excellent in solid solution strengthening ability, and is an essential component for securing a high strength of tensile strength TS ≧ 500 MPa in the steel sheet of the present invention. In order to obtain such an effect, when Nb is not added, it is necessary to add 0.07 mass% or more. However, when Nb is added in an amount of 0.02 mass% or more, the tensile strength TS ≧ 500 MPa can be obtained if the addition amount of P is 0.02 mass% or more. On the other hand, regardless of whether Nb is added or not, if the P content exceeds 0.15 mass%, the effect is saturated, and the adverse effect of reducing corrosion resistance also occurs. .

Nb: 0.06 mass% or less Nb is a component that forms carbonitrides with C and N, finely precipitates, refines crystal grains, and increases steel sheet strength. Like P, in the steel of the present invention, It is a preferred component for securing a high strength with a tensile strength TS ≧ 500 MPa, and the amount of P added, which has an adverse effect on corrosion resistance, can be reduced. In order to acquire the said effect, addition of 0.02 mass% or more is preferable. On the other hand, if the Nb content exceeds 0.06 mass%, the above effect is saturated and only the raw material cost is increased, so the upper limit is 0.06 mass%. Preferably, it is the range of 0.03-0.05 mass%.

The amount of Mn and N contained in the steel plate of the present invention may be in the range normally contained as a steel plate for cans, and specifically the following ranges are preferred.
Mn: 1.0 mass% or less Mn is an element having an effect of preventing hot brittleness due to S and an effect of increasing the steel plate strength in addition to having a deoxidizing effect. In order to obtain such an effect, it is preferable to add 0.2 mass% or more. On the other hand, when Mn is added in excess of 1.0 mass%, Mn is concentrated on the surface of the steel sheet and may cause surface contamination, so Mn is set to 1.0 mass% or less. Preferably, it is 0.7 mass% or less.

N: 0.03 mass% or less N is a component that forms a nitride with Al or Nb to refine crystal grains and increase the strength of steel. 0.03 mass% or less is preferable. However, excessive reduction leads to an increase in steelmaking costs, so the lower limit is preferably about 0.001 mass%.

  In the steel sheet of the present invention, the balance other than the above components is preferably composed of Fe and inevitable impurities. However, as long as the effects of the present invention are not adversely affected, it does not refuse to contain components other than those described above.

Next, mechanical properties that the steel sheet of the present invention should have will be described.
Tensile strength TS: 500 MPa or more The tensile strength TS of the steel sheet of the present invention needs to be 500 MPa or more. This is because when TS is less than 500 MPa, fatigue strength is low and breakage occurs when used as a substrate material for printing for a long time.

Total elongation: 2% or more The total elongation of the steel sheet of the present invention needs to be 2% or more. This is because the helix fold when mounted on the drum of a rotary press is usually subjected to a 180 ° bending of a bending R = 1t (t: plate thickness) which is almost close to a contact bending. According to the test results of the inventors, the elongation in the tensile test needs to be at least 2% in order to prevent cracking (breaking) even if the bending is performed. Therefore, the total elongation of the steel sheet of the present invention is 2% or more.

In addition, the steel sheet of the present invention preferably satisfies the following items.
Plate thickness: more than 0.13 mm The steel plate of the present invention preferably has a plate thickness exceeding 0.13 mm. This is because, when the plate thickness is 0.13 mm or less, the product is weak and easily folds, making handling difficult during plate making and printing. More preferably, the product plate thickness is 0.15 mm or more. On the other hand, the upper limit of the plate thickness is not particularly limited, but if it becomes too thick, the weight of the steel plate itself increases and handling becomes difficult, so the upper limit is preferably set to 0.25 mm.

Ear elongation and middle elongation: 1% or less each in steepness Further, the cold rolled steel sheet of the present invention measures the ear elongation and middle elongation (also referred to as belly elongation) when the flatness is placed on a surface plate. When the following formula:
Steepness = (peak height of ear extension or medium extension) / mountain pitch x 100 (%)
It is preferable that each of the steepness levels defined by (1) is 1% or less. If the steepness of the edge extension or middle extension exceeds 1%, the ear extension and the middle extension are large, so that when the paper is wound around the plate cylinder, it does not completely adhere to the plate cylinder and may cause printing failure. is there.

Next, the manufacturing method of the steel plate for printed boards of this invention is demonstrated.
The steel sheet of the present invention is a continuous casting method after the steel having the above-described component composition is melted by a generally known method such as a converter or an electric furnace, and after secondary refining such as degassing treatment as necessary. The steel slab is formed by a known method such as ingot-making and ingot rolling. This steel slab is then charged in a heating furnace, reheated and hot rolled. At this time, the steel slab after continuous casting may be hot-rolled after being lightly heated in a heating furnace without being cooled to room temperature, or may be adopted an energy saving process in which hot rolling is performed immediately after continuous casting.

The hot rolling step can be carried out by a generally known method, but in order to obtain excellent flatness, the hot rolling finish finishing temperature (FDT) is not less than the Ar ₃ transformation point, preferably (Ar ₃ transformation point +50). It is desirable that the temperature be equal to or higher than (° C.). This is because the temperature of the edge portion of the hot-rolled steel sheet is likely to decrease, and the finish rolling end temperature is likely to be lower than the Ar ₃ transformation point. As a result, the hot rolled structure of the edge portion becomes coarse and soft, and it is easy to cause an ear elongation failure during cold rolling. The winding temperature after rolling may be a normal temperature, but is preferably 500 to 650 ° C.

  The steel sheet after hot rolling is rolled to a desired product thickness by one cold rolling after pickling. In this case, the cold rolling reduction ratio is preferably in the range of 80 to 95%. If it is less than 80%, it is necessary to make the thickness of the hot-rolled steel sheet, which is a material of the cold-rolled steel sheet, excessively thin, which unfavorably increases the rolling load of hot rolling. On the other hand, if it exceeds 95%, the cold rolling reduction ratio becomes too large, and the rolling load increases, and surface defects such as heat streaks and shape defects such as ear elongation are likely to occur.

  The cold-rolled steel sheet is then recrystallized in an annealing process. As a method of recrystallization annealing, there are a box annealing method and a continuous annealing method. In order to obtain a high-strength steel sheet and to ensure a good shape, it is preferable to employ a continuous annealing method. It is preferable that the annealing temperature at this time is 730-780 degreeC.

  The steel sheet after continuous annealing is then subjected to temper rolling with a rolling reduction in the range of 0.5 to 1.5% for the purpose of improving the mechanical properties such as surface roughness adjustment, shape correction and loss of yield elongation. It is preferable to apply. Furthermore, if necessary, shape correction with an elongation of about 0.1 to 3% may be performed with a shape correction facility such as a tension leveler.

  The steel plate after the continuous annealing may be used as a product as it is, or may be passed through an electroplating line and then subjected to a plating treatment such as chromium plating or tin plating, and then the product.

Steel having the component composition shown in Table 1 is melted in a converter and made into a steel slab by a continuous casting method. After that, the steel slab is reheated to 1250 ° C., and then the finish rolling finish temperature is 890 to 920 ° C. (≧ A hot rolled sheet having a thickness of 1.8 mm was obtained by hot rolling with an Ar ₃ transformation point. Subsequently, these hot-rolled sheets were pickled, rolled at a final sheet thickness of 0.18 mm by only one cold rolling, and subjected to continuous annealing at 750 ° C. for 30 seconds, and then 0.9% The temper rolling was performed at a reduction ratio of 1 to obtain a cold-rolled annealed sheet. The cold-rolled annealed plate is further subjected to shape correction with an elongation rate of 0.3% using a tension leveler, then passed through a finishing line for shape measurement, and a sample material is collected. And subjected to a tensile test and a bending test. In the shape measurement, on the surface plate of the finishing line, the ear elongation, the middle elongation, and their generated pitch were measured, and the above-mentioned steepness was measured. For the tensile test, a JIS No. 5 tensile test piece was taken in parallel with the rolling direction from the above test material, and the tensile strength TS and total elongation El were measured. A test piece was collected and subjected to close contact bending with a bending R = 0 t (t: plate thickness) to examine whether or not cracking occurred.

  The results of the above measurements are shown together in Table 1. From the results shown in Table 1, the cold-rolled steel sheet produced according to the present invention has higher yield strength and excellent flatness than the cold-rolled steel sheet produced by the conventional method. It turns out that it is suitable.

  The cold-rolled steel sheet whose shape was corrected with a tension leveler was then further subjected to chrome plating in an electroplating line to produce tin-free steel (TFS) that satisfies the plating coverage specified in JIS G3315-2002. . And about this TFS, the shape measurement, the tensile test, and the bending test were done like the said cold-rolled steel plate, The result became the same as the result shown in Table 1. From this, it was confirmed that the cold-rolled steel sheet having a plating layer produced according to the present invention is also excellent as a steel sheet for a printed circuit board.

  The technology of the present invention is not limited to steel plates for printed boards, but can also be applied to steel plates for cans used for containers such as food cans, beverage cans, miscellaneous cans and the like.

It is a graph which shows the influence of Nb and P content which has on the tensile strength of the steel plate for printed circuit boards.

Claims (3)

C: 0.02-0.09 mass%,
Mn: 1.0 mass% or less ,
P: 0.07 to 0.15 mass% ,
Al: 0.031 mass% or less,
N: 0.03 mass% or less is contained,
The balance has a component composition consisting of Fe and inevitable impurities,
A steel sheet for printed circuit boards having a tensile strength of 500 MPa or more and a total elongation of 2% or more. C: 0.02-0.09 mass%,
Mn: 1.0 mass% or less ,
P: 0.02-0.15 mass%,
Nb: 0.02 to 0.06 mass% ,
Al: 0.031 mass% or less,
N: 0.03 mass% or less is contained,
The balance has a component composition consisting of Fe and inevitable impurities,
A steel sheet for printed circuit boards having a tensile strength of 500 MPa or more and a total elongation of 2% or more. The said steel plate has a plating layer in the surface, The steel plate for printed circuit boards of Claim 1 or 2 characterized by the above-mentioned.

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