JP4508140B2 - Built-in module - Google Patents

Description

The present invention relates to a component built-in module wiring pattern insulating a resin base material to form to Rume Tsu key circuit layer Stainless transfer substrate, parts are built with the wiring pattern is formed by transferring by the transfer is there.

  More specifically, the present invention relates to a technique for forming a very fine circuit by transferring a circuit (wiring pattern) formed by plating onto an insulating resin substrate, and the plated circuit layer is an insulating resin. The present invention relates to a technique capable of improving the adhesion of a plated circuit layer to an insulating resin substrate without being subjected to a surface treatment such as desmear that is generally performed by being embedded in the substrate. . Furthermore, the present invention relates to a technique that allows a component to be mounted on a stainless steel transfer substrate with a plated circuit layer by solder reflow or the like, and that the component can be transferred and embedded together with the circuit.

  In recent years, improvement in wiring density of wiring boards has led to downsizing of boards and shortening of wiring distances between components, and electronic devices have become more functional and smaller and thinner. As a method for manufacturing a substrate, a build-up multilayering method or the like is used. By this method, a multilayer wiring substrate is manufactured by laminating a wiring layer (conductor layer, metal film) via an electrical insulating layer (resin layer). Yes.

  In forming a wiring pattern on such a wiring board, there are the following methods. In other words, a copper-clad laminate in which a metal foil such as copper foil is laminated and integrated with an insulating substrate in advance and a wiring pattern is formed using an etching method on this, and wiring on the surface of the insulating resin substrate by plating or the like In some cases, a layer is formed directly, and this wiring layer is etched to form a predetermined wiring pattern.

  By the way, when the wiring layer is formed on the surface of the electrical insulating layer by plating, the surface of the electrical insulating layer is previously roughened in order to improve the adhesion between the wiring layer formed by plating and the electrical insulating layer. Conventionally, after performing (desmear treatment), plating is performed. The roughening treatment is performed by etching the surface of the electrical insulating layer using an etchant such as potassium permanganate or sodium permanganate (see, for example, Patent Document 1).

A general plating method includes a pretreatment process such as degreasing of the resin surface, an etching process, a catalyzing process, an accelerating process, an electroless copper plating process, and an electrolytic copper plating process. The reason why the plating process is performed after various processing steps without directly performing the plating process on the surface of the insulating resin base material is that the resin is so hydrophobic that it is difficult to wet with water. If the surface of the insulating resin substrate is plated as it is, a metal film cannot be formed on the surface. When surface treatment is performed in an aqueous solution such as plating, the surface of the insulating resin substrate must be made hydrophilic so that it can easily get wet with water. Furthermore, in order for the insulating resin substrate surface and the plating metal to be in close contact with each other, the insulating resin substrate surface is made hydrophilic and activated by creating a polar group on the resin surface, and irregularities such as micropores are formed on the resin surface. It is necessary to roughen the surface. In the roughening treatment, the treatment is performed in the order of a swelling step with a swelling solution such as an organic solvent, an etching step with an etching solution such as a sodium permanganate, and a neutralization step with a neutralizing solution such as a sulfuric acid. This process is an etching process. Furthermore, for the deposition of plating nuclei, it is necessary to activate palladium on the resin surface, so the insulating resin substrate is immersed in a catalyzing solution containing palladium chloride and tin chloride, and the catalyst metal is adsorbed on the resin surface. . This process is a catalyzing process. When the catalyzing process is performed, the complex salt of palladium and tin is adsorbed on the surface of the insulating resin base material. Therefore, in the accelerating process, an accelerating solution containing hydrochloric acid, sulfuric acid, NH ₄ F · HF, or the like is used. In this process, palladium metal serving as a plating nucleus is deposited on the resin surface. Next, in the electroless plating treatment step, the copper metal is electrolessly plated on the resin surface by the catalytic action of the plating nuclei deposited on the resin surface to form a metal film on the resin surface. The metal film formed by electroless plating serves as a power feeding layer for performing electrolytic plating, and is usually about 0.5 to 2.0 μm thick. Thereafter, by the electrolytic copper plating process, electrolytic copper plating is performed until a predetermined thickness that can be used for a wiring pattern or the like is formed, thereby forming a metal film.

  In addition, as a technique for improving the adhesion between the wiring layer and the electrical insulating layer, various methods have been proposed in which the surface of the insulating resin substrate is modified and then electroless plating is performed on the surface. For example, a method has been proposed in which an insulating resin substrate is placed in an amine compound gas or amide compound gas atmosphere, the surface of the insulating resin substrate is irradiated with an ultraviolet laser, and then electroless plating is performed (for example, , See Patent Document 2).

  In addition, as a pretreatment for performing electroless plating on an insulating resin base material, a method of irradiating the surface of the insulating resin base material with ultraviolet rays and then performing electroless plating on the surface of the insulating resin base material has been proposed. (For example, refer to Patent Document 3).

  Moreover, the method of improving adhesiveness is also proposed by performing the surface treatment process made to contact the alkaline solution containing the nonionic surfactant which has a polyoxyethylene bond (for example, refer patent document 4). .

In addition, after the surface modification of the insulating resin substrate by ultraviolet irradiation, the silane coupling agent having an amino-based functional group is adsorbed to promote the application of the tin-palladium catalyst. A method for improving the adhesion of a metal film formed thereon by electroless plating has also been proposed (see, for example, Patent Document 5).
JP 2002-57456 A JP-A-6-87964 JP-A-8-253869 JP-A-10-88361 JP-A-10-310873

When the conductor is filled in the concave portion on the surface of the electrical insulating layer on which the uneven surface is formed by the roughening treatment, the wiring pattern is brought into close contact with the electrical insulating layer by the anchor action. However, when the unevenness on the surface of the electrical insulating layer becomes large, when forming the wiring pattern by etching the wiring layer, the unevenness on the surface adversely affects the accuracy of pattern formation and forms an extremely fine wiring pattern with high accuracy. There was a problem that I could not. The surface roughness in the case of the conventional roughening treatment is about R _{max 4 to 5} μm. Incidentally, Patent Documents 1 and 3 describe techniques for improving the surface roughness so that R _{max is} 1 μm or less.

  In addition, when the surface roughness of the electrical insulating layer increases, there is a problem in that transmission loss of high-frequency signals, which is one of the electrical characteristics of the wiring board, increases. Furthermore, when the surface roughness of the electrically insulating layer is increased, there is a problem that the migration resistance is lowered. Therefore, it is necessary to reduce the surface roughness of the electrical insulation layer as much as possible, and there is a need for a technique that can improve the adhesion between the electrical insulation layer and the wiring layer. As shown in the above, there is known a method of subjecting the surface of an insulating resin substrate to plasma treatment, ion beam irradiation, and ultraviolet irradiation. It is considered that the generation of —OH groups and —NH groups by plasma treatment or ultraviolet treatment contributes to the improvement of the adhesion of electroless plating. In order to generate these functional groups effectively, it is necessary to consider the composition of the insulating resin base material, but there is also a problem that the resin design is limited.

  These methods are based on the premise that the surface of the insulating resin base material is etched and roughened, and this etching process is generally performed using a chromic acid / sulfuric acid mixed solution or a dichromic acid / sulfuric acid mixed solution. The insulating resin substrate is immersed in a strong oxidizing etching solution such as chloric acid, sulfuric acid / perchloric acid mixed solution, or the like. However, since this etchant is a chemical solution with high danger and pollution, it is necessary to pay careful attention to its handling and discharge treatment. In the plating process in metal film formation, work management is required. The burden is large. Furthermore, in order to make it easier to roughen the resin surface by etching, it is necessary to consider such as mixing some components that are easily etched into the resin, which limits the properties of the cured resin. There is also a problem of end. In addition to this, it is necessary to prepare a treatment agent for promoting the modification of the surface of the insulating resin base material separately from the normal treatment liquid, and there is a problem that the number of treatment steps is increased and the treatment cost is increased. Furthermore, it is necessary to install an ultraviolet ray irradiation and a plasma processing apparatus, which causes an increase in equipment cost, and is a great obstacle for supplying inexpensive products.

The present invention has been made in view of the above, primarily, it is an object to provide a parts products built-in module that can be obtained high adhesion to the insulating resin base material of the plating circuit layer .

  More specifically, the present invention provides a technique for forming a circuit board by forming a fine circuit on a stainless steel substrate by pattern plating, transferring only the circuit to an insulating resin substrate, and performing etching. There is no need to form a circuit, and a very fine circuit can be formed. The circuit surface on the side embedded in the insulating resin substrate has a very small roughness and has very excellent characteristics as a high-frequency circuit. In addition, the stainless steel substrate has sufficient heat resistance to mount components on the plated circuit layer, so that deformation and the like do not occur due to reflow processing, etc., and the positional accuracy of the circuit and components is extremely stable. The circuit substrate (stainless steel base) is peeled off after the transfer and removed from the product, eliminating the need for a conventional interposer and making a very thin multilayer circuit board. It can be done.

The component built-in module according to claim 1 of the present invention is a stainless steel transfer substrate with a plated circuit layer in which a plated circuit layer 3 is formed by plating using metal particles 2 attached to the surface of a stainless steel substrate 1 as a core. In the material 4, the metal particles 2 are deposited on the roughened surface obtained by roughening the surface of the stainless steel substrate 1 by a substitution reaction between the iron ions constituting the stainless steel substrate 1 and the metal ions of the metal particles 2. The plating circuit layer 3 is sequentially laminated in a wiring pattern, and is composed of a plurality of plating layers 5 made of one or more types of plating, and adjacent plating layers 5 farther plating layer 5 of the plating circuit layer 3 is being plated with a circuit layer stent which has a wide become structure towards the width from stainless steel substrate 1 than the width of the near-plated layer 5 on the stainless steel substrate 1 of Characterized by using the scan transfer substrate 4. The component 8 is mounted on the plated circuit layer 3 of the stainless steel transfer substrate 4 with the plated circuit layer, and the plated circuit layer 3 and the component 8 are stacked on the insulating resin substrate 6 and thermocompression-molded. The component built-in module is formed by transferring the plated circuit layer 3 to the insulating resin substrate 6 and embedding the component 8 by peeling off the substrate .

  The invention according to claim 2 is characterized in that, in claim 1, the plating layer 5 farthest from the stainless steel substrate 1 among the plurality of plating layers 5 constituting the plating circuit layer 3 is formed by solder plating. Is.

  The invention according to claim 3 is characterized in that, in claim 1 or 2, the surface of the plated circuit layer 3 is roughened.

According to the component built-in module according to claim 1 of the present invention, when a stainless steel transfer substrate with a plated circuit layer is laminated on an insulating resin substrate and thermocompression-molded, among the plurality of plated layers constituting the plated circuit layer Since the end portion of some of the plating layers penetrates deeper into the insulating resin base material, it is possible to obtain high adhesion of the plated circuit layer to the insulating resin base material. In particular, even when a fine wiring pattern is formed with a plated circuit layer, high adhesion of such a wiring pattern to an insulating resin substrate can be obtained. Then, when the plated circuit layer is transferred and embedded in the insulating resin base material, the adhesiveness of the plated circuit layer to the insulating resin base material can be increased. In addition, the surface of the circuit board is flattened by transferring and embedding the plated circuit layer on which the part is mounted on the insulating resin base material. Can be easily obtained, and the thickness of the multilayer circuit board can be stabilized.

  According to the second aspect of the present invention, components can be easily mounted on the plating layer farthest from the stainless steel substrate, that is, the outermost layer of the plating circuit layer, by solder reflow (reflow soldering).

  According to the invention which concerns on Claim 3, the adhesiveness with respect to the insulating resin base material of a plating circuit layer can be obtained still higher.

  Embodiments of the present invention will be described below.

The stainless steel transfer substrate with a plated circuit layer used in the present invention can be manufactured using the stainless steel transfer substrate 21 after the stainless steel transfer substrate 21 is manufactured by attaching the metal particles 2 to the stainless steel substrate 1. First, the stainless steel transfer substrate 21 will be described.

FIG. 8 shows an example of the stainless steel transfer base material 21, which is produced by attaching 0.05 to 5 mg / m ^{2 of} metal particles 2 serving as the core of plating on one or both surfaces of the stainless steel base material 1. can do.

  An appropriate material is used as the stainless steel substrate 1, but in order to facilitate the roughening particularly when the surface roughening treatment is performed, the chromium content is preferably 10 to 20% by mass and the nickel content. Is 0 to 15% by mass. Examples of such a stainless steel substrate 1 include SUS301 and SUS304. Since stainless materials having these compositions are widely used and easily available, manufacturing costs can be reduced. Surface roughening is possible with materials other than these, but it becomes difficult to control the concentration of the etching solution for the roughening treatment.

  The thickness of the stainless steel substrate 1 is preferably 20 to 200 μm. Thus, when the thickness of the stainless steel substrate 1 is as thin as 200 μm or less, the stainless steel substrate 1 is cracked in the insulating resin substrate 6 when it is peeled off after being thermocompression-molded on the insulating resin substrate 6. Can be prevented and the peelability can be improved. Further, when the plated circuit layer 3 is formed on the stainless steel substrate 1 and the component 8 is mounted on the plated circuit layer 3, heat treatment such as bump mounting, wire bonding, and reflow soldering is required. However, since the stainless steel substrate 1 is as thin as 200 μm or less, heat can be easily raised, and the component 8 can be mounted quickly and reliably. However, if the thickness of the stainless steel substrate 1 is greater than 200 μm, the above effects may not be sufficiently obtained. When the insulating resin substrate 6 has flexibility, or when the stainless steel substrate 1 requires sufficient rigidity due to processing limitations, the thickness exceeds 200 μm. May be used. In addition, it is difficult to obtain the stainless steel substrate 1 having a thickness of less than 20 μm and it is difficult to handle, and problems such as hip breakage tend to occur particularly in the reflow process when the component 8 is mounted.

  The metal particles 2 can be attached to the stainless steel substrate 1 by etching the stainless steel substrate 1 using an etching solution containing metal ions of the metal particles 2. Thus, while the surface of the stainless steel substrate 1 is very finely roughened as shown in FIG. 8, the metal ions and the iron ions constituting the stainless steel substrate 1 are replaced, and the metal ions Metal is deposited in a complicated manner on the roughened surface of the stainless steel substrate 1.

  In this way, by treating the surface of the stainless steel substrate 1 with the etching solution, the surface of the stainless steel substrate 1 can be roughened and the metal particles 2 can be attached to the surface. is there. At this time, as the etching solution, the surface of the stainless steel substrate 1 is treated by using the etching solution containing iron ions and metal ions having a smaller ionization tendency than iron, so that the surface of the stainless steel substrate 1 is treated. Simultaneously with the roughening treatment, metal particles having a smaller ionization tendency than iron can be adhered to the surface to form a surface to be treated.

  More specifically, the etching solution contains ferric chloride or a strongly acidic etching solution (iron chloride etching solution) containing iron ions by containing ferric chloride and ferrous chloride. It is preferable to use a metal ion having a smaller ionization tendency than iron, and the metal ion having a smaller ionization tendency than iron preferably includes a copper ion or a nickel ion.

  As described above, when the metal ionization tendency of the metal particles 2 is smaller than the iron ionization tendency of the stainless steel substrate 1, the metal particles 2 are deposited on the surface of the stainless steel substrate 1. The deposited metal particles 2 can be changed depending on the difference in ionization tendency. In this way, dissimilar metal particles that cannot be obtained simply by roughening with conventional etching technology by using an etching solution containing metal ions that are less ionized than iron in a commonly used iron chloride etching solution It is possible to obtain a surface to be processed to which 2 is attached. In addition, as a metal smaller than the ionization tendency of iron, tin etc. can be mentioned besides copper and nickel.

  In particular, as described above, when the metal particles 2 are particles of at least one of copper and nickel, it is possible to manufacture the stainless steel transfer substrate 21 having excellent plating adhesion at the lowest cost. is there.

  Here, in the drilling of the normal stainless steel base material 1 or the like, processing with less side etching is performed using an etching solution having a redox potential of a certain level or more. When the particles 2 are attached, it is preferable to perform the treatment with an etching solution having a lower oxidation-reduction potential (for example, 475 to 550 mV) than that of normal stainless steel processing. In general, the processing liquid used for etching the stainless steel substrate 1 is mixed with an acid or a stabilizer to improve the processing efficiency. Is also possible.

In the present invention, it is preferable to set the adhesion amount of the metal particles 2 serving as the core of the plating to 0.05 to 5 mg / m ^{2. By} setting in this way, good transferability is ensured. On the other hand, it is possible to improve the plating adhesion to the stainless steel substrate 1 which is usually difficult to be plated. Therefore, a fine wiring pattern can be transferred to the insulating resin substrate 6 and formed with high accuracy.

More specifically, as shown in FIG. 8, metal particles 2 are complicatedly entangled and deposited on the surface of the roughened stainless steel substrate 1, and the metal particles 2 serve as the core of plating and are usually plated. It is possible to improve the plating adhesion to the difficult stainless steel substrate 1. In order to prevent the plating from being peeled off, the adhesion amount of the metal particles 2 may be increased. However, in order to obtain transferability, the adhesion must be controlled within a certain range. That is, when the adhesion amount of the metal particles 2 is in the range of 0.05 to 5 mg / m ² , the peel strength between the plated circuit layer 3 and the stainless steel substrate 1 is 100 to 500 g / cm (98.1 to 490 N / m), the best balance between plating adhesion and transferability is maintained, and even if heated, the plated circuit layer 3 does not drop carelessly and heat resistance is improved. In FIG. 8, the roughened surface is formed on one surface of the stainless steel substrate 1 and the metal particles 2 are attached. However, the roughened surface is formed on both surfaces of the stainless steel substrate 1 and the metal particles 2 are attached. It may be attached.

Here, adjustment of the adhesion amount of the metal particles 2 can be performed by adjusting in advance the content of metal ions of the metal particles 2 in the etching solution. For example, by using a ferric chloride solution containing 0.1 to 5.0 mass% copper ions or a ferric chloride solution containing 0.1 to 5.0 mass% nickel ions, Although the adhesion amount of the particle | grains 2 can be set to the range of 0.05-5 mg / m < ² >, it is not specifically limited to these. Further, the etching processing time for attaching the metal particles 2 can be set to 15 to 90 seconds. However, the treatment time is not limited to this depending on the concentration of the treatment liquid. Moreover, the adhesion amount of the metal particles 2 adhering to the surface of the stainless steel transfer substrate 21 as shown in FIG. 8 can be confirmed by measuring with ESCA or the like.

Incidentally, when the amount of deposition of the metal particles 2 is less than 0.05 mg / m ^2, before the adhesion to stainless steel substrate 1 of the plating circuit layer 3 decreases, to transfer the plating circuit layer 3 in the insulating resin base material 6 The plated circuit layer 3 is peeled off from the stainless steel substrate 1. Further, when the component 8 is mounted on the plated circuit layer 3 by the solder reflow process, it leads to the occurrence of peeling or swelling. On the contrary, when the adhesion amount of the metal particles 2 is more than 5 mg / m ² , the transferability of the plated circuit layer 3 to the insulating resin base material 6 is deteriorated. That is, the adhesion of the plated circuit layer 3 to the stainless steel substrate 1 becomes too high, and the plated circuit layer 3 becomes difficult to peel off from the stainless steel substrate 1 and the plated circuit layer 3 cannot be transferred to the insulating resin substrate 6. It is.

Further, the surface to be processed of the stainless steel transfer substrate 21 shown in FIG. 8 is preferably formed so that the surface roughness Ra is 1.0 μm or less. This surface roughness is obtained by measuring with a cut-off value λ _c = 0.80 mm and a measurement length L = λ _c × 5 = 4.0 mm based on JIS B0601. Here, the smaller the surface roughness is, the higher the accuracy of the subsequent circuit formation can be expected. This roughness also has a relationship with the deposition rate of the metal particles 2, and the amount of deposition of the metal particles 2 needs to be optimized. If this roughness becomes too small, the adhesion of resist such as pattern plating deteriorates, and peeling of edges tends to occur in a strong acid or strong alkali atmosphere such as a plating solution, thereby forming a fine pattern. Because there is a possibility that a problem will occur, care should be taken.

  Furthermore, the etching solution is not limited to a ferric chloride solution, and any etching solution that can roughen and etch the stainless steel substrate 1 such as a copper chloride solution can be selected freely. .

  Next, the stainless steel transfer substrate 4 with a plated circuit layer will be described. The stainless steel transfer substrate 4 with a plated circuit layer can be manufactured as shown in FIG. 1 using the stainless steel transfer substrate 21 described above. That is, a photomask film (not shown) in which a wiring resist pattern is formed after the plating resist layer 10 is formed on the surface to be processed (the surface on which the metal particles 2 are attached) of the stainless transfer substrate 21 shown in FIG. ) And then developed, as shown in FIG. 1 (b), the plating resist layer 10 in the portion to be plated is removed, the surface to be processed of the stainless steel transfer substrate 21 is exposed, and plating is performed. A portion of the plating resist layer 10 (first plating resist layer 10a) that is not to be left remains. Then, using the exposed metal particles 2 on the surface to be processed as the core of plating, plating is performed as shown in FIG. Subsequently, after the plating resist layer 10 is formed on the surface of the first plating resist layer 10a, it is exposed using a photomask film (not shown) on which a wiring pattern is formed and then developed, as shown in FIG. 1 (d). In addition, the plating resist layer 10 where plating is performed is removed to expose the surface of the first plating layer 5a, and the plating resist layer 10 (second plating resist layer 10b) where plating is not performed remains. Here, the portion not covered with the second plating resist layer 10b is formed wider than the exposed surface of the first plating layer 5a. Then, by plating the exposed surface of the first plating layer 5a, the second plating layer 5b is formed as shown in FIG. At this time, if the second plating layer 5b becomes mushroom-like beyond the surface of the second plating resist layer 10b, the pattern accuracy may be adversely affected and it may be difficult to form a fine circuit. The plating layer 5b does not exceed the surface of the second plating resist layer 10b. In the case shown in FIG. 1E, the exposed surface of the second plating layer 5a is flush with the surface of the second plating resist layer 10b. The second plating layer 5b may be formed with the same plating type as the first plating layer 5a, or may be formed with a plating type different from that of the first plating layer 5a. Thereafter, when the plating resist layer 10 (the first plating resist layer 10a and the second plating resist layer 10b) is removed, a stainless steel transfer substrate 4 with a plating circuit layer as shown in FIG. 1 (f) can be obtained. In this stainless steel transfer substrate 4 with a plated circuit layer, a plated circuit layer 3 having a substantially T-shaped cross section is formed of two layers, a first plated layer 5a and a second plated layer 5b. In addition, as plating, electrolytic plating, such as electrolytic copper plating, can be performed. In addition, in the case where a residual component still remains between the plated circuit layers 3 after the plating resist layer 10 is removed, the residual component may be cleaned and removed by soft etching or the like.

  In the present invention, the plated circuit layer 3 is not limited to that shown in FIG. 1 (f) described above, and may be as shown in FIG. The plating circuit layer 3 shown in FIG. 2 is also formed by repeatedly forming the plating resist layer 10 and the plating layer 5 in the same manner as shown in FIG. The plated circuit layer 3 shown in FIG. 2 (a) has a substantially T-shaped cross section similar to that shown in FIG. 1 (f), but is composed of three layers of first to third plated layers 5a, 5b, 5c. Has been. The plated circuit layer 3 shown in FIG. 2 (b) is also composed of three layers of first to third plated layers 5a, 5b, and 5c, which are formed in a substantially horizontal H-shaped cross section. . Further, the plated circuit layer 3 shown in FIG. 2C is also composed of three layers of first to third plated layers 5a, 5b, and 5c, which are formed in a cross-like cross section. And the plating seed | species which forms each plating layer 5 is not specifically limited. For example, in the case shown in FIG. 2, the first plating layer 5a can be formed by copper plating, the second plating layer 5b can be formed by nickel plating, and the third plating layer 5c can be formed by gold plating. In this case, since the third plating layer 5c, which is the outermost layer, is formed by gold plating, it can be easily connected later by the gold wire 18, and the first to third plating layers 5a, 5b, 5c It is not necessary to form all of them with gold plating, and only the third plating layer 5c, which is the outermost layer, needs to be formed with gold plating, leading to cost reduction. Further, the number of plating layers 5 constituting the plating circuit layer 3 may be four or more.

  FIG. 3 shows another example of the plated circuit layer 3, which is formed as follows. First, by forming the plating resist layer 10 and the plating layer 5, the first to third plating layers 5a, 5b, and 5c are stacked with the same width as shown in FIG. Then, when etching is performed using a processing solution that selectively etches only the second plating layer 5b, a plating circuit layer 3 having a substantially horizontal H-shaped cross section as shown in FIG. 3B can be obtained. it can. Specifically, for example, when the first and third plating layers 5a and 5c are formed by nickel plating and the second plating layer 5b is formed by copper plating, only the copper plating can be selectively etched. Etching may be performed using a processing solution that can be used.

  As described above, in the present invention, the plating circuit layer 3 is composed of a plurality of plating layers 5 made of one type or a plurality of types of plating. Furthermore, the plating circuit layer 3 has a structure in which the width of the plating layer 5 far from the stainless steel substrate 1 is wider than the width of the plating layer 5 near the stainless steel substrate 1 among the adjacent plating layers 5. . This point will be described in detail with reference to FIG. In the structure shown in FIG. 2A, the first and second plating layers 5a and 5b are adjacent to each other, and the second and third plating layers 5b and 5c are adjacent to each other. Focusing on the second plating layers 5a and 5b, the width of the plating layer 5 (second plating layer 5b) farther from the stainless steel substrate 1 than the width of the plating layer 5 (first plating layer 5a) close to the stainless steel substrate 1 is used. Is wider. Further, in the case shown in FIG. 2B, focusing on the second and third plating layers 5b and 5c, the stainless steel substrate 1 is larger than the width of the plating layer 5 (second plating layer 5b) close to the stainless steel substrate 1. The width of the plating layer 5 (third plating layer 5c) far from the center is wider. Further, in the case shown in FIG. 2C, when focusing on the first and second plating layers 5 a and 5 b, the stainless steel substrate 1 is larger than the width of the plating layer 5 (first plating layer 5 a) close to the stainless steel substrate 1. The width of the plating layer 5 (second plating layer 5b) far from the center is wider. Note that what is shown in FIG. 3B is the same as that shown in FIG.

  And according to the stainless steel transfer substrate 4 with a plated circuit layer on which the plated circuit layer 3 having the above structure is formed, an insulating resin base is used in manufacturing the circuit board 7 and the component built-in module 9 (both described later). When thermocompression molding is performed over the material 6, the end of some of the plating layers 5 of the plurality of plating layers 5 constituting the plating circuit layer 3 penetrates deeper into the insulating resin substrate 6. High adhesion of the layer 3 to the insulating resin substrate 6 can be obtained. Taking the example shown in FIG. 2 as an example, in FIG. 2A, the end portions of the second and third plating layers 5b, 5c bite deeper into the insulating resin substrate 6, and in FIG. 2B, The end portion of the third plating layer 5c bites deeper into the insulating resin base material 6, and in FIG. 2C, the end portion of the second plating layer 5b bites deeper into the insulating resin base material 6, With respect to the plated circuit layer 3, the pulling strength can be improved. In particular, even when a fine wiring pattern is formed with such a plated circuit layer 3, it is possible to obtain high adhesion of the wiring pattern to the insulating resin substrate 6. In addition, when the plated circuit layer 3 is formed, a predetermined amount of the metal particles 2 is attached to the surface of the stainless steel substrate 1 in advance, so that excellent transferability and plating adhesion can be obtained. Therefore, if the stainless steel substrate 1 is peeled off after the stainless steel substrate 4 with the plated circuit layer is directly laminated on the insulating resin substrate 6 and thermocompression-molded, the circuit board 7 can be easily obtained. If the stainless steel substrate 1 with a plated circuit layer on which the component 8 is mounted is superimposed on the insulating resin substrate 6 and thermocompression-molded, and then the stainless steel substrate 1 is peeled off, the component built-in module 9 can be easily obtained. is there. Further, since the etching is not performed in the circuit formation process shown in FIGS. 1A to 1F, a fine wiring pattern can be accurately formed by the plated circuit layer 3. FIG.

  Next, the circuit board 7 will be described. This circuit board 7 can be manufactured as shown in FIG. 4 using the above-described stainless steel transfer substrate 4 with a plated circuit layer. That is, as shown in FIGS. 4 (a) and 4 (b), the plated circuit layer 3 of the stainless steel transfer substrate 4 with the plated circuit layer is laminated on the insulating resin substrate 6 in a semi-cured state (B stage state) and thermocompression-molded. When the plated circuit layer 3 is transferred to the insulating resin base material 6 by peeling the stainless steel base material 1 after (heat-press molding), a circuit board 7 as shown in FIG. 4C can be obtained. . Thereafter, if the surface of the circuit board 7 is washed by soft etching or the like, the circuit board 7 with higher reliability can be obtained. The thermocompression molding may be performed under the condition that the insulating resin layer formed of the molded insulating resin base material 6 maintains the B stage state, or under the condition that the insulating resin layer is in the C stage state. it can.

  Here, as the insulating resin base material 6, for example, an appropriate electrically insulating thermosetting resin composition such as an epoxy resin composition or a material formed using a thermoplastic resin composition may be used. it can. Specifically, the resin composition is molded into a sheet shape, heat-dried and resin sheet such as a polyimide film in a semi-cured state, or a glass woven fabric or an organic fiber sheet is impregnated with the resin composition, A sheet material composed of an electrically insulating resin composition in a B-stage state, such as a prepreg that has been heated and dried to be in a semi-cured state, can be used. The insulating resin substrate 6 can be formed of a single sheet material, or can be formed by laminating and integrating a plurality of sheet materials.

  Further, as shown in FIG. 4A, the surface of the plated circuit layer 3 may be roughened before the stainless transfer substrate 4 with the plated circuit layer is overlaid on the insulating resin substrate 6. Thereby, the adhesiveness with respect to the insulating resin base material 6 of the plated circuit layer 3 can be obtained still higher. In addition, the roughening process of the surface of the plating circuit layer 3 can be performed by a blackening process, for example, and the roughness of the plating circuit layer 3 roughened by this is about 0.2-0.3 micrometer in Ra. is there. Since the roughness is low, transmission loss is not adversely affected.

  By the way, with a stainless steel plate that is usually used, if it is a very rigid circuit board 7, it can be peeled off, but in the case of a thin circuit board 7, the circuit board 7 must be turned up and peeled off, There is a possibility that fine cracks or the like may occur in the circuit board 7 due to mechanical stress, and it is easy to cause a problem in reliability. However, as described above, by making the stainless steel substrate 1 into a foil shape having a thickness of 200 μm or less, stainless steel is formed. By turning up the base material 1, it is possible to easily peel off a very delicate circuit board 7 without generating fine cracks or the like. Thus, in order to improve peelability, it is preferable that the thickness of the stainless steel substrate 1 is in the range of 20 to 200 μm as described above. In this case, the stainless steel substrate 1 is peeled from the insulating resin substrate 6. In this case, the stainless steel base material 1 can be easily peeled off while being turned up from the insulating resin base material 6, and excessive stress is applied to the insulating resin base material 6 at this time. Further, it is possible to prevent the circuit board 7 from being damaged.

  And according to the circuit board 7 as shown in FIG.4 (c), when the plating circuit layer 3 is transcribe | transferred and embedded at the insulating resin base material 6, with respect to the insulating resin base material 6 of the plating circuit layer 3 High adhesion can be obtained. Therefore, it is not necessary to perform a roughening process (desmearing process) on the surface of the insulating resin base 6 in advance at the stage shown in FIG. 4A, so that the roughening process is not performed. Thus, it is possible to prevent an increase in transmission loss of the high-frequency signal and to prevent a decrease in migration resistance. Further, the exposed surface of the plated circuit layer 3 and the outer surface of the insulating resin substrate 6 are flush with each other by being transferred and embedded so that the plated circuit layer 3 is exposed on the surface of the insulating resin substrate 6. When the multi-layer circuit board is obtained by using a plurality of such circuit boards 7 as a core material and multi-layering by a build-up method or the like, the surface of the circuit board 7 becomes flat. It is possible to stabilize the thickness of the substrate.

  In addition, two circuit boards 7 can be manufactured at a time as shown in FIG. 5 by using a stainless steel transfer substrate 4 with a plated circuit layer in which plated circuit layers 3 are formed on both sides. That is, as shown in FIGS. 5A and 5B, a stainless steel transfer substrate 4 with a plated circuit layer having a plated circuit layer 3 formed on both sides is sandwiched between two semi-cured insulating resin substrates 6. After the thermocompression molding, the two insulating resin base materials 6 are peeled off, whereby two circuit boards 7 can be obtained as shown in FIG.

  Next, the component built-in module 9 will be described. This component built-in module 9 can also be manufactured as shown in FIG. 6 using the above-described stainless transfer substrate 4 with a plated circuit layer. That is, as shown in FIG. 6A, the component 8 is first mounted on the plated circuit layer 3 of the stainless transfer substrate 4 with the plated circuit layer.

As the component 8, a passive component such as a chip-shaped resistor, a chip-shaped capacitor, or a chip-shaped inductor can be used, and such a component 8 can be connected to the plated circuit layer 3 with solder 16 and mounted. . Here, it is preferable that the plating layer 5 farthest from the stainless steel substrate 1 among the plurality of plating layers 5 constituting the plating circuit layer 3 is formed by solder plating. Specifically, for example, in the plated circuit layer 3 shown in FIG. 2A, the third plated layer 5c is preferably formed by solder plating. Thus, the component 8 can be easily mounted on the plating layer 5 farthest from the stainless steel substrate 1, that is, the outermost layer of the plating circuit layer 3 by solder reflow (reflow soldering).
Further, as the component 8, an active component such as a semiconductor bare chip can be used, and the component 8 is connected to the plated circuit layer 3 by a bump 17 such as a solder ball as shown in FIG. May be. Further, as shown in FIG. 7B, the component 8 is connected to the plated circuit layer 3 with an adhesive, and the other plated circuit layer 3 and the component 8 are mounted by wire bonding with a gold wire 18 or the like. Also good.
By the way, when heating is performed when the component 8 is mounted, the component 8 and the plated circuit layer 3 may be peeled off from the stainless steel substrate 1 in the conventional device. By improving the adhesion between the stainless steel substrate 1 and the plated circuit layer 3, the component 8 and the plated circuit layer 3 can be prevented from falling off when the component 8 is mounted by heating. After the plated circuit layer 3 is transferred and embedded in the insulating resin base material 6, only the stainless steel base material 1 can be easily peeled off. In addition, when heating is performed when the component 8 is mounted, if the stainless steel substrate 1 is thick, the heat does not easily rise, and problems such as bump mounting, wire bonding, reflow soldering, etc. are likely to occur. By using the material 1, it can be easily heated, and uniform heat treatment is facilitated as a whole.

  6 (a) and 6 (b), the plated circuit layer 3 and the component 8 of the stainless transfer substrate 4 with the plated circuit layer on which the component 8 is mounted are stacked on the insulating resin substrate 6 and thermocompression-molded. Later, by peeling the stainless steel substrate 1, the plated circuit layer 3 is transferred to the insulating resin substrate 6 and the component 8 is embedded, whereby a component built-in module 9 as shown in FIG. 6C can be obtained. it can.

  In the component built-in module 9 manufactured as described above, the plated circuit layer 3 is transferred to the insulating resin base material 6 and embedded, whereby the adhesion of the plated circuit layer 3 to the insulating resin base material 6 is achieved. Can be obtained high. Further, the plated circuit layer 3 on which the component 8 is mounted is transferred and embedded so as to be exposed in the insulating resin base material 6, so that the exposed surface of the plated circuit layer 3 and the outer surface of the insulating resin base material 6 face each other. Since the unevenness is eliminated and the surface of the component built-in module 9 becomes flat, a multilayer circuit board incorporating the component 8 can be easily obtained by using a plurality of such component built-in modules 9 to form a multilayer. In addition, the thickness of the multilayer circuit board can be stabilized. Further, since the component 8 is built in, it can be made smaller and thinner than the conventional one.

  In the circuit board 7 and the component built-in module 9 described above, a hole is formed by laser processing, drilling, or the like, and then the hole is plated or filled with a conductive paste. Can be formed.

  Hereinafter, the present invention will be specifically described by way of examples.

( Reference Example 1)
As the stainless steel substrate 1, SUS301 (76% Fe, 17% Cr, 7% Ni), tempered 3 / 4H, 100 μm thick, ferric chloride solution containing 1.0% by mass of copper ions A stainless steel transfer substrate 21 as shown in FIG. 8 was obtained by performing an etching process on one surface of the stainless steel substrate 1 for 60 seconds at an oxidation-reduction potential of 500 mV and a specific gravity of 1.46. The adhesion amount of the metal particles 2 (copper particles) was 0.5 mg / m ² .

  Next, using the stainless steel transfer substrate 21, a plating circuit layer 3 as shown in FIG. 2A is formed by sequentially performing formation of the plating resist layer 10, exposure, development, and electrolytic plating. A layered stainless steel transfer substrate 4 was obtained. However, the plating circuit layer 3 is formed by laminating copper plating (thickness 10 μm, circuit width 300 μm), nickel plating (thickness 20 μm, circuit width 350 μm), and gold plating (thickness 2 μm, circuit width 350 μm) sequentially from the surface to be processed. A three-layer structure was formed.

Next, an epoxy resin sheet (thickness: 100 μm) is used as the insulating resin substrate 6, and as shown in FIGS. 4 (a) and 4 (b), the stainless steel transfer substrate 4 with a plated circuit layer is overlaid on the epoxy resin sheet, Thermocompression molding was performed at 100 ° C. and 5 kg / cm ² (0.49 MPa). And after cooling this, the stainless steel substrate 1 was peeled off to obtain a circuit board 7 as shown in FIG.

  The plated circuit layer 3 of the stainless steel transfer substrate 4 with the plated circuit layer is not inadvertently peeled off before the transfer, and when the circuit board 7 is manufactured, the plated circuit layer 3 is entirely epoxy. It was confirmed that it was transferred to the resin sheet.

( Reference Example 2)
FIG. 8 is the same as Reference Example 1 except that the etching process is performed for 30 seconds with a ferric chloride solution containing 3.0 mass% copper ions (redox potential 500 mV, specific gravity 1.46). A stainless transfer substrate 21 as shown in FIG. The adhesion amount of the metal particles 2 (copper particles) was 2.0 mg / m ² .

  Next, using the stainless steel transfer substrate 21, a plating circuit layer 3 as shown in FIG. 2A is formed by sequentially performing formation of the plating resist layer 10, exposure, development, and electrolytic plating. A layered stainless steel transfer substrate 4 was obtained. However, the plating circuit layer 3 is formed by laminating copper plating (thickness 10 μm, circuit width 1 mm), nickel plating (thickness 20 μm, circuit width 1.5 mm), and gold plating (thickness 2 μm, circuit width 1.5 mm) in order from the surface to be processed. As a result, a three-layer structure was formed.

Next, an epoxy prepreg (thickness: 200 μm) is used as the insulating resin substrate 6, and as shown in FIGS. 4 (a) and 4 (b), the stainless steel transfer substrate 4 with a plated circuit layer is overlaid on the epoxy prepreg, and 80 ° C. Thermocompression bonding was performed under conditions of 3 kg / cm ² (0.29 MPa). And after cooling this, the stainless steel substrate 1 was peeled off to obtain a circuit board 7 as shown in FIG.

  The plated circuit layer 3 of the stainless steel transfer substrate 4 with the plated circuit layer is not inadvertently peeled off before the transfer, and when the circuit board 7 is manufactured, the plated circuit layer 3 is entirely epoxy. It was confirmed that it was transferred to the prepreg.

(Example 1 )
FIG. 8 is similar to Reference Example 1 except that the etching treatment is performed for 45 seconds with a ferric chloride solution (oxidation-reduction potential 520 mV, specific gravity 1.45) containing 2.0 mass% nickel ions. A stainless transfer substrate 21 as shown in FIG. The adhesion amount of the metal particles 2 (nickel particles) was 1.0 mg / m ² .

  Next, by using the stainless steel transfer substrate 21, the plating resist layer 10 is formed, exposed, developed, and electroplated in this order, so that the stainless steel transfer substrate 4 with a plated circuit layer as shown in FIG. Got. However, the plated circuit layer 3 was formed in a two-layer structure by sequentially stacking nickel plating (thickness 20 μm, circuit width 200 μm) and solder plating (thickness 50 μm, circuit width 250 μm) from the surface to be processed.

  Next, a component 8 (chip resistance) was mounted on the plated circuit layer 3 by solder reflow. At the time of mounting by this solder reflow, the plated circuit layer 3 did not peel from the stainless steel substrate 1.

Next, as the insulating resin substrate 6, three epoxy resin sheets (thickness: 200 μm) are used, and as shown in FIGS. The material 4 was stacked on the epoxy resin sheet, and thermocompression-bonded under conditions of 100 ° C. and 5 kg / cm ² (0.49 MPa). And after cooling this, the stainless steel base material 1 was peeled off to obtain a component built-in module 9 as shown in FIG.

  The plated circuit layer 3 of the stainless steel transfer substrate 4 with the plated circuit layer is not inadvertently peeled off before the transfer, and when the component built-in module 9 is manufactured, the plated circuit layer 3 is all It was confirmed that it was transferred to the epoxy resin sheet.

( Reference Example 3 )
FIG. 8 is similar to Reference Example 1 except that the etching process is performed for 45 seconds with a ferric chloride solution (oxidation-reduction potential 520 mV, specific gravity 1.45) containing 1.0 mass% nickel ions. A stainless transfer substrate 21 as shown in FIG. The adhesion amount of the metal particles 2 (nickel particles) was 0.8 mg / m ² .

  Next, the surface of the stainless steel transfer substrate 21 is formed as shown in FIG. 3A by sequentially performing formation of the plating resist layer 10, exposure, development, and electrolytic plating using the stainless steel transfer substrate 21. Nickel plating (thickness 5 μm), copper plating (thickness 10 μm), and nickel plating (thickness 20 μm) were sequentially laminated with the same diameter (land diameter 2 mm). Then, using a general processing solution capable of selectively etching only copper plating, etching is performed about 50 μm from the side surface, thereby forming a plated circuit layer 3 (land) as shown in FIG. did.

Next, an epoxy prepreg (thickness: 150 μm) is used as the insulating resin substrate 6, and the stainless steel transfer substrate 4 with a plated circuit layer is overlaid on the epoxy prepreg as shown in FIGS. Thermocompression bonding was performed under conditions of 5 kg / cm ² (0.49 MPa). And after cooling this, the stainless steel substrate 1 was peeled off to obtain a circuit board 7 as shown in FIG.

  The plated circuit layer 3 of the stainless steel transfer substrate 4 with the plated circuit layer is not inadvertently peeled off before the transfer, and when the circuit board 7 is manufactured, the plated circuit layer 3 is entirely epoxy. It was confirmed that it was transferred to the prepreg.

( Reference Example 4 )
As the stainless steel substrate 1, SUS301 (76% Fe, 17% Cr, 7% Ni), tempered 3 / 4H, 100 μm thick, ferric chloride solution containing 1.0% by mass of copper ions The stainless steel transfer base material 21 was obtained by performing an etching process for 30 seconds on both surfaces of the stainless steel base material 1 at an oxidation-reduction potential of 500 mV and a specific gravity of 1.46. The adhesion amount of the metal particles 2 (copper particles) was 0.2 mg / m ² per side.

  Next, using the stainless steel transfer substrate 21, a plating circuit layer 3 as shown in FIG. 2A is formed by sequentially performing formation of the plating resist layer 10, exposure, development, and electrolytic plating. A layered stainless steel transfer substrate 4 was obtained. However, the plating circuit layer 3 is formed by laminating copper plating (thickness 10 μm, circuit width 1 mm), nickel plating (thickness 20 μm, circuit width 1.5 mm), and gold plating (thickness 2 μm, circuit width 1.5 mm) in order from the surface to be processed. As a result, a three-layer structure was formed.

Next, two polyimide films (thickness 50 μm) are used as the insulating resin substrate 6, and as shown in FIGS. 5A and 5B, the stainless transfer substrate 4 with a plated circuit layer is replaced with the two polyimide films. And thermocompression-bonded under the conditions of 200 ° C. and 5 kg / cm ² (0.49 MPa). And after cooling this, as shown in FIG.5 (c), two circuit boards 7 were obtained by peeling two polyimide films.

  The plated circuit layer 3 of the stainless steel transfer substrate 4 with the plated circuit layer is not inadvertently peeled off before the transfer, and when the circuit board 7 is manufactured, all of the plated circuit layer 3 is polyimide. It was confirmed that it was transferred to the film.

( Reference Example 5 )
As the stainless steel substrate 1, SUS301 (76% Fe, 17% Cr, 7% Ni), tempered 3 / 4H, 100 μm thick, ferric chloride solution containing 1.0% by mass of copper ions A stainless steel transfer substrate 21 as shown in FIG. 8 was obtained by performing an etching process on one surface of the stainless steel substrate 1 for 60 seconds at an oxidation-reduction potential of 500 mV and a specific gravity of 1.46. The adhesion amount of the metal particles 2 (copper particles) was 0.5 mg / m ² .

  Next, using the stainless steel transfer substrate 21, a plating circuit layer 3 as shown in FIG. 2A is formed by sequentially performing formation of the plating resist layer 10, exposure, development, and electrolytic plating. A layered stainless steel transfer substrate 4 was obtained. However, the plating circuit layer 3 is formed by laminating copper plating (thickness 35 μm, circuit width 300 μm), nickel plating (thickness 25 μm, circuit width 350 μm), and gold plating (thickness 2 μm, circuit width 350 μm) in this order from the surface to be processed. A three-layer structure was formed. The surface of the plated circuit layer 3 formed in this way was roughened by blackening. The roughness of the plated circuit layer 3 after the roughening treatment was 0.2 to 0.3 μm in Ra.

Next, an epoxy resin sheet (thickness 150 μm) is used as the insulating resin substrate 6, and as shown in FIGS. 4A and 4B, the stainless steel transfer substrate 4 with a plated circuit layer is overlaid on the epoxy resin sheet, Thermocompression molding was performed at 100 ° C. and 5 kg / cm ² (0.49 MPa). And after cooling this, the stainless steel substrate 1 was peeled off to obtain a circuit board 7 as shown in FIG.

  The plated circuit layer 3 of the stainless steel transfer substrate 4 with the plated circuit layer is not inadvertently peeled off before the transfer, and when the circuit board 7 is manufactured, the plated circuit layer 3 is entirely epoxy. It was confirmed that it was transferred to the resin sheet.

Moreover, while the plating circuit layer 3 is not subjected to roughening treatment, the plating peel strength is about 600 g / cm (588 N / m), whereas the plating circuit layer 3 is subjected to roughening treatment in this reference example. The peel strength was about 900 g / cm to 1 kg / cm (883 to 981 N / m).

An example of the manufacturing method of the stainless steel transcription | transfer base material with a plating circuit layer is shown, (a)-(f) is sectional drawing. The other example of a plated circuit layer is shown, (a)-(c) is sectional drawing. The other example of the formation method of a plating circuit layer is shown, (a) (b) is sectional drawing. An example of the manufacturing method of a circuit board is shown, (a)-(c) is sectional drawing. The other example of the manufacturing method of a circuit board is shown, (a)-(c) is sectional drawing. An example of the manufacturing method of a component built-in module is shown, (a)-(c) is sectional drawing. An example of the stainless steel transfer base material with a plating circuit layer which mounted components is shown, (a) (b) is sectional drawing. An example of a stainless steel transcription | transfer base material is shown, (a) is sectional drawing, (b) is an expanded sectional view of the surface part of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stainless steel base material 2 Metal particle 3 Plating circuit layer 4 Stainless steel transfer base material with plating circuit layer 5 Plating layer 6 Insulation resin base material 7 Circuit board 8 Parts 9 Parts built-in module

Claims (3)

A stainless steel transfer substrate with a plated circuit layer in which a plated circuit layer is formed by plating using metal particles attached to the surface of the stainless steel substrate as a core, and the metal particles constitute the stainless steel substrate The surface of the stainless steel substrate is deposited and adhered to the roughened surface by a substitution reaction between iron ions and metal ions of the metal particles, and the plated circuit layer is sequentially laminated in a wiring pattern. And a plurality of plating layers made of one or more kinds of plating species, and the width of the plating layer farther from the stainless steel substrate than the width of the plating layer close to the stainless steel substrate among the adjacent plating layers. Write with Rume Tsu key circuit layer stainless transfer substrate a wide made structures have said plating circuit layer,
After mounting the component on the plated circuit layer of the stainless steel transfer substrate with the plated circuit layer and superposing the plated circuit layer and the component on the insulating resin substrate and performing thermocompression molding, the stainless steel substrate is peeled off to remove the insulating resin substrate. A component built-in module, wherein a plated circuit layer is transferred to a material and the component is embedded . 2. The component built-in module according to claim 1, wherein a plating layer farthest from the stainless steel substrate among the plurality of plating layers constituting the plating circuit layer is formed by solder plating. The component built-in module according to claim 1, wherein the surface of the plated circuit layer is roughened.

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