JP2004134792A - Resin wiring board with pins - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pin-attached resin wiring board in which flat pins are soldered to pin joining portions of a resin wiring board, and to connect the flat pins with the flat pins in a form suitable for miniaturization of the flat pins. An object of the present invention is to provide a resin wiring board with pins that can enhance the reliability of joining with a part.
SOLUTION: A resin wiring board with pins according to the present invention for solving the above-mentioned problems,
A flat pin composed of a rod-shaped part having a diameter of 0.35 mm or less and a concentric plate-shaped large-diameter part formed at one end of the rod-shaped part and having a diameter larger than the rod-shaped part,
A pin-attached resin wiring board soldered at the large-diameter portion to a pin joint provided on a main surface of the board,
When the diameter of the rod portion of the flat pin is S and the diameter of the large diameter portion is W,
The ratio (W / S) of the diameter of the rod-shaped portion to the diameter of the large-diameter portion is set to be 2.16 or more and 2.67 or less.
[Selection diagram] Fig. 1

Description

The present invention relates to a resin wiring board with pins, and more particularly, to an interlayer insulating layer such as a PGA (pin grid array) type package wiring board in which electronic components such as semiconductor integrated circuit elements (ICs) are mounted and sealed. The present invention relates to a resin wiring board with pins, in which pins (input / output terminals) are soldered to a large number of pin joints (electrodes) formed on the main surface of the wiring board.

A PGA-type resin wiring substrate (hereinafter, also simply referred to as a substrate) has a large number of pad-shaped pin joints (electrodes) used for mounting electronic components such as an LSI and an IC chip on one main surface thereof. The other main surface is provided with a number of pins for inserting into a socket provided on a motherboard or the like. As this pin, for example, a nail-shaped flat pin composed of a bar-shaped portion and a plate-shaped large-diameter portion (having a larger diameter than the bar-shaped portion) formed at one end thereof is generally used. . Further, the flat pin is joined and formed so that a large diameter portion thereof is opposed to a pin joining portion of a substrate via a solder layer formed by soldering.

In a resin wiring board with pins of the type described above, in order to achieve high integration and high density of electronic components such as an LSI, an IC chip or a chip capacitor to be mounted, the size and the number of connection terminals (number of pins) are reduced. The number of pins is increasing. For this reason, even in the flat pin of the device itself, the size of the pin is reduced by reducing the diameter of the rod portion.

JP 2001-267451 A JP 2001-217341 A JP 2001-358277 A

Regarding the miniaturization of the flat pin provided in the resin wiring board with pins, in recent years, the diameter of the bar portion has been reduced to, for example, about 0.30 mm, specifically, 0.35 mm or less (for example, 0.25 mm to 0.35 mm). The following) and reducing the diameter are required as a numerical range. Therefore, when reducing the diameter of the rod portion of the flat pin in this way, it is necessary to optimize the size of the large diameter portion of the flat pin in a form corresponding to the diameter of the reduced rod portion. is there. If this adjustment is not made, the joint strength between the large diameter portion of the flat pin and the pin joint in the resin wiring board with pins cannot be sufficiently ensured. If an excessive external force occurs in the axial direction of the flat pin or in the direction of its inclination, the vicinity of the interface between the solder layer to which the flat pin is joined and the pin joint or the interface between the large diameter portion of the flat pin and the solder layer Peeling will occur. This means that the quality such as the electrical characteristics required of the resin wiring board with pins cannot be maintained.

The present invention has been made in view of the above problems. For a resin wiring board with pins with flat pins soldered to the pin joints of the resin wiring board, the joint reliability between the flat pins and the pin joints is improved in a form suitable for miniaturization of the flat pins. It is an object of the present invention to provide a resin wiring board with pins that can be raised.

The resin wiring board with pins of the present invention for solving the above-mentioned problems,
A flat pin composed of a rod-shaped part having a diameter of 0.35 mm or less and a concentric plate-shaped large-diameter part formed at one end of the rod-shaped part and having a diameter larger than the rod-shaped part,
A pin-attached resin wiring board soldered at the large-diameter portion to a pin joint provided on a main surface of the board,
When the diameter of the rod portion of the flat pin is S and the diameter of the large diameter portion is W,
The ratio (W / S) of the diameter of the rod-shaped portion to the diameter of the large-diameter portion is set to be 2.16 or more and 2.67 or less.

The pins used in the resin wiring board with pins of the present invention include a rod-shaped portion and a large-diameter portion formed at one end of the rod-shaped portion and having a diameter larger than that of the rod-shaped portion. , So-called flat pins. The diameter of the rod portion is 0.35 mm or less (for example, 0 mm or less) in order to cope with high integration and high density of electronic components such as LSIs and IC chips mounted on a resin wiring board with pins. 0.25 mm or more and 0.35 mm or less: If it is less than 0.25 mm, the pin strength may be reduced). When the diameter of the rod portion of the flat pin is reduced in this way, in order to ensure sufficient bonding strength between the pin bonding portion provided on the main surface of the substrate and the large diameter portion of the flat pin, the diameter of the large diameter portion is reduced. It is necessary to optimize the size of the part. Therefore, in the present invention, when the diameter of the rod portion of the flat pin is S and the diameter of the large diameter portion is W, the ratio (W / S) between the diameter of the rod portion and the diameter of the large diameter portion is 2. It is 16 or more and 2.67 or less. When the ratio (W / S) is less than 2.16, the role of the large diameter portion as a base is impaired, and when the axial direction of the flat pin is set to the vertical direction, sufficient joint strength against horizontal external force is obtained. I can't keep it. Further, the bonding area of the large diameter portion with the solder layer formed by soldering is reduced, so that it is not possible to maintain sufficient bonding strength against external force in a vertically upward direction. On the other hand, when the ratio (W / S) exceeds 2.67, the ratio becomes excessively larger than necessary with respect to the diameter of the rod-shaped portion, which is equivalent to requesting excessive bonding strength. That is, if the ratio (W / S) is secured with 2.67 as the upper limit, it is possible to sufficiently secure the bonding strength. Further, when the ratio (W / S) exceeds 2.67, it can be said that there is a disadvantage in cost due to an increase in the formation volume of the large diameter portion.

Next, in the resin-made wiring board with pins of the present invention, assuming that the thickness of the large-diameter portion is T, the ratio (T / S) between the diameter of the rod-shaped portion and the thickness of the large-diameter portion is 0. .40 or more and 0.67 or less. As described above, by optimizing the diameter of the large diameter portion of the flat pin, it is possible to significantly secure the joining strength between the flat pin and the pin joint in a form suitable for downsizing the flat pin. However, it is desirable that the thickness of the large-diameter portion of the flat pin is also optimized. Therefore, in the present invention, the ratio (T / S) between the diameter of the rod portion and the thickness of the large diameter portion is set to 0.40 or more and 0.67 or less. If the ratio (T / S) is less than 0.40, the thickness becomes excessively thin, and the role of the large diameter portion as a base may be impaired. That is, the large diameter portion of the pin cannot maintain sufficient strength to support the rod portion, and the pin is easily broken. The ease with which the pin is broken according to the thickness of the large diameter portion is defined as the base strength, and will be described in detail below. Here, for example, when it is assumed that an external force in the horizontal direction (the axial direction of the pin is a vertical direction) is applied to the tip of the rod portion of the pin, the stress on the pin generated by the external force is It occurs intensively near the boundary between the rod-shaped portion and the large diameter portion. The magnitude of the stress is (proportional) according to the length from the stressed portion to the tip of the pin. Therefore, when the entire length of the pin is the same, the stress starts from the stressed portion to the tip of the pin. The greater the length of the large diameter portion, that is, the smaller the thickness of the large diameter portion, the more stress is applied near the boundary between the rod portion and the large diameter portion. Also, not only the external force in the horizontal direction and the external force applied to the tip of the pin, but also the external force applied to the rod-shaped portion of the pin can be handled as the horizontal external force applied to the tip of the pin. Is valid for all external forces applied to the rod portion of the pin. For the above reasons, the smaller the thickness of the large diameter portion, the more easily the pin is broken by stress.

On the other hand, if the ratio (T / S) exceeds 0.67, the base strength is required more than necessary, and it is sufficient to set the upper limit of the ratio (T / S) to 0.67. It can be said that there is. In addition, there is a disadvantage in cost due to an increase in the volume of the large diameter portion.

Further, the ratio (W / S) of the diameter of the rod portion to the diameter of the large diameter portion is 2.33 or more and 2.67 or less, and the ratio of the diameter of the rod portion to the thickness of the large diameter portion ( T / S) is not less than 0.40 and not more than 0.54. The reason for optimizing the diameter and thickness of the large diameter portion of the flat pin is to secure the joint strength between the flat pin and the pin joint and the base strength. However, even in the state where the bonding strength and the base strength are secured in this way, if an unintended external force is excessively applied to the flat pins, the resin wiring board with pins may be damaged starting from the flat pins. . This damage mode can be roughly classified into three. The first is a mode in which only the pin is broken as shown in FIG. 6A, and the second is a mode in which the vicinity of the interface between the large diameter portion of the pin and the solder layer is peeled off as shown in FIG. The third is a mode in which the vicinity of the interface between the solder layer for joining the pins and the pin joint as shown in FIG. 6C is peeled off. In the first mode, the substrate and the solder layer are not damaged because only the pins are damaged as compared with the second and third modes. Therefore, it is desirable that only the pin be broken if damage occurs.

In order to break only the pin when an external force is applied to the pin in this manner, the ratio of the diameter of the rod-shaped portion to the diameter of the large-diameter portion (W / S = 2.16 to 2.67) The ratio of the diameter of the rod portion to the diameter of the large diameter portion is large (W / W) within the range of the ratio of the diameter of the rod portion to the thickness of the large diameter portion (T / S = 0.40 to 0.67). /S=2.33 to 2.67), and the ratio of the diameter of the rod portion to the thickness of the large diameter portion is desirably small (T / S = 0.40 to 0.54). Here, the reason why the ratio (W / S) between the diameter of the rod-shaped portion and the diameter of the large diameter portion is required to be limited to a large range is that the ratio (W / S) is related to the bonding strength as described above. If the ratio (W / S) is small and the bonding strength is weak, the pin and solder having weak bonding strength, or the vicinity of the interface between the solder and the pin joint is peeled off before the pin is damaged when an external force is applied. This is because the possibility that the substrate and the solder layer are damaged is increased. Further, the ratio (T / S) between the diameter of the rod portion and the thickness of the large diameter portion is required to be limited to a small range because the ratio (T / S) is related to the base strength as described above. If (T / S) is large and the base strength is strong, the pin is hard to be broken due to the strength of the large diameter portion when an external force is applied, and the external force is transmitted to the vicinity of the interface between the pin and the solder or the solder-pin joint. As a result, the interface is peeled off, and the possibility of damaging the substrate and the solder layer increases.

The thickness of the solder layer formed based on the soldering is adjusted to be 0.30 mm or less in the thickness direction from the first main surface of the pin joint to the flat pin side. Become. If it exceeds 0.30 mm, the IC may be mounted on a substrate and sealed to form a semiconductor device, and when a pin is inserted into a socket of a motherboard, solder may hit the socket and a problem may occur in the set of the semiconductor device. . The lower limit is set to 0.10 mm. If the thickness is less than 0.10 mm, the pin holding area decreases, and the bonding strength between the solder and the pin decreases.

で は In the resin wiring board with pins of the present invention, the flat pins are made of a metal containing at least copper. Copper is suitable as a material for flat pins because of its excellent conductivity. In addition, since copper is soft and deforms when stress is generated, it has an advantage that the pin is hardly broken. Note that a pin made of copper alone is too soft as a pin, so that sufficient strength may not be ensured in some cases. Therefore, it is more preferable to use a copper alloy containing a small amount of metal such as iron (for example, Alloy 194 (CDA alloy @ C19400 (based on ASTM B @ 465)) or the like).

As is clear from the above description, the resin-made wiring board with pins of the present invention has a large diameter portion and a large thickness portion of the pin having a size that satisfies predetermined conditions. In addition, when an external force acts on the pin, only the pin is damaged, and the solder portion and the substrate are not easily broken. Therefore, according to the present invention, it is possible to obtain a resin wiring board with pins that can provide high bonding strength and can be easily repaired even when damaged. Further, the wiring board of the present invention is made of a resin material. However, in the case of a resin wiring board, low-melting-point solder must be used for soldering the pins, so that the bonding strength of the pins tends to be low. However, according to the present invention, even when such solder is used, the bonding strength can be reliably increased.

Embodiments of the resin wiring board with pins of the present invention will be described in detail with reference to the drawings. FIG. 1 is a side view of a resin wiring board with pins 1 according to the present invention. FIG. 2 is an enlarged sectional view of FIG. 1, and FIG. 3 is a further enlarged sectional view. The resin wiring board 1 with pins has a rectangular shape in plan view (each 50 mm in length and width, 1 mm in thickness), and a core board (about 0.8 mm) is made of a plurality of resin insulating layers mainly composed of epoxy resin and copper. A resin substrate 12 having a structure in which a number of internal wiring layers are laminated. On the upper main surface 13, a large number of electrodes (not shown) for connecting a semiconductor integrated circuit element IC to be mounted are formed, and an internal wiring layer of each layer (not shown) is formed. Vias to be connected are formed. A large number of conductive layers (copper) in plan view, for example, connected to vias, are formed on the lower main surface 14, and the surface thereof is plated with nickel and gold to form a pin joint 15. The pin joints 15 are formed at intervals of, for example, about 1.3 mm.

The solder resist layer 17 made of epoxy resin is formed on the upper and lower main surfaces 13 and 14 of the substrate 12 so as to cover substantially the entire surface. The height H1 of the surface 171 of the solder resist layer 17 from the first main surface 151 of the pin joint 15 is about 20 μm. However, in the present embodiment, the solder resist layer 17 is opened so as to cover the periphery of the first main surface 151 of the pin joint 15 with a predetermined width, and concentrically extends from the center of the first main surface 151 of the pin joint 15. It is formed so as to be exposed to. Incidentally, in this example, the length D1 of the pin joint (conductor layer) 15 is set to about 1.13 mm, and the exposed portion thereof (the opening of the solder resist layer 17, that is, the pin joint is not covered by the solder resist layer). The length D2 in the direction parallel to the main surface of the substrate (part), that is, the diameter of the soldering surface is set to about 1.03 mm.

On the other hand, the pin 11 joined in the present embodiment is made of a copper alloy such as Alloy 194 (CDA alloy @ C19400 (based on ASTM B @ 465)) or the like, and is a round bar-shaped rod having a circular cross section (about 0.30 mm in diameter). 111, and a nail-shaped flat pin having a concentric disk-shaped large-diameter portion 112 with a diameter larger than that of the rod-shaped portion at the upper end thereof. The surface of the large-diameter portion 112 facing the first main surface 151 of the upper pin joint 15 is arranged so as to be concentric with the first main surface 151 of the pin joint 15 and is provided with an appropriate amount of solder. It is soldered (a solder layer formed by soldering is referred to as a solder layer 16). Note that the solder is a solder having a composition having a melting point higher than the soldering temperature of the semiconductor integrated circuit element IC (for example, Pb 82% / Sn 10% / Sb 8%, or Sn 95% and Sb 5%).

When a Pb-Sn-based solder such as Pb 82% / Sn 10% / Sb 8% is used, since a large amount of soft lead (Pb) is contained, when an unintended external force is excessively applied to the pin 11, the stress generated in the pin 11 Can be received when the solder layer 16 is deformed, so that it is possible to prevent the resin wiring board 1 with pins from being damaged by external force (the above three types of damage).

In the present embodiment, when the diameter of the rod portion 111 of the pin 11 is S and the diameter of the large diameter portion 112 (length in a direction parallel to the main surface of the substrate) is W, the diameter of the rod portion and the diameter of the large diameter portion are equal to each other. (W / S) is in the range of 2.33 to 2.67 (for example, when the diameter S of the rod-shaped portion 111 is 0.3 mm, the diameter W of the large-diameter portion 112 is 0.73 mm or 0.75 mm) When the thickness of the large diameter portion 112 (length in the direction perpendicular to the main surface of the substrate) is T, the ratio (T / S) of the diameter of the rod portion to the thickness of the large diameter portion is 0.40 to 0.40. It is within a range of 0.54 (for example, when the diameter S of the rod-shaped portion 111 is 0.3 mm, the thickness T of the large-diameter portion 112 is 0.15 mm). The height L from the surface 171 of the solder resist layer 17 to the tip of the pin 11 is about 2.00 mm (for example, 2.08 mm).

Also, the large-diameter portion 112 of the pin and the pin joint 15 do not directly contact each other, and the upper surface 113 of the large-diameter portion 112 facing the first main surface 151 of the pin joint 15 and the first main surface of the pin joint 15 do not contact each other. The large diameter portion 112 of the pin and the pin joint 15 are joined with the solder layer 16 interposed between the pin 151 and the surface 151. The distance between the upper surface 113 of the large diameter portion and the first main surface 151 of the pin joint is about 10 to 30 μm. It is preferable that the large-diameter portion 112 of the pin does not directly contact the pin joint portion 15 from the viewpoint of securing the solder attachment area, but the present invention is not limited to this, and the pin may directly contact.

(4) The height H2 of the pin joint 15 of the solder layer 16 from the first main surface 151 is set to 0.3 mm or less. When the thickness is 0.3 mm or more, when a pin is inserted into the socket of the motherboard, the socket hits the solder layer 16, which hinders setting on the motherboard.

高 The height H2 of the solder layer 16 is set to be higher than the position of the lower surface 114 of the pin large diameter portion 112. In the present embodiment, the solder covers the periphery of the lower surface 114 in the vicinity, but if the height H2 of the solder layer 16 is in the range of 0.3 mm or less, the entire lower surface 114 is covered with solder. It does not matter. It is desirable that the height H2 of the solder layer 16 is higher than the position of the lower surface 114 of the pin large-diameter portion 112 from the viewpoint of bonding strength. However, the present invention is not limited to this, and as shown in FIG. The height H2 of the pin 16 may be lower than the position of the lower surface 114 of the pin large diameter portion 112.

The solder layer 16 spreads wet toward the surface of the first main surface 151 of the pin joint 15, and in this embodiment, the diameter of the solder wetting spread is covered by the solder resist layer in the pin joint. It is formed so as to have the same length as the length D2 in the direction parallel to the main surface of the substrate where there is no portion, but is not limited to this, and may be smaller than D2, or the slope 172 of the opening of the solder resist 17. May be partially covered.

Here, specific examples of the wiring board with pins of the present invention will be described together with comparative examples. FIG. 7 shows the ratio (W / S) between the diameter of the rod-shaped portion of the pin and the diameter of the large-diameter portion and the ratio (T / S) between the diameter of the rod-shaped portion of the pin and the thickness of the large-diameter portion in each sample. Show. However, the diameters S of the rod-shaped portions of the pins are all 0.30 mm. Below, in the bullet point,
(1) A pin having a ratio (W / S) of 2.00 (diameter W of the large diameter portion is 0.60 mm) and a ratio (T / S) of 0.83 (thickness T is 0.25 mm) Comparative Example: not belonging to any claim) 1 pin.
(2) A pin having a ratio (W / S) of 2.23 (diameter W of the large diameter portion is 0.67 mm) and a ratio (T / S) of 0.50 (thickness T is 0.15 mm) Example: It belongs to claims 1 and 2). 2 pins.
(3) A pin having a ratio (W / S) of 2.23 (diameter W of the large diameter portion is 0.67 mm) and a ratio (T / S) of 0.67 (thickness T is 0.20 mm) ( Example: It belongs to claims 1 and 2). 3 pins.
(4) A pin having a ratio (W / S) of 2.40 (the diameter W of the large diameter portion is 0.72 mm) and a ratio (T / S) of 0.50 (thickness T is 0.15 mm) ( Example: Sample No. 1 belongs to claims 1 and 2 and further belongs to claim 3). 4 pins.
(5) A pin having a ratio (W / S) of 2.50 (the diameter W of the large diameter portion is 0.75 mm) and a ratio (T / S) of 0.50 (thickness T of 0.15 mm) ( Example: Sample No. 1 belongs to claims 1 and 2 and further belongs to claim 3). 5 pins.
Each of the pins of sample Nos. 1 to 5 was soldered to a resin wiring board having a pin joint having a diameter of 1.03 mm in a direction parallel to the main surface of the substrate not covered with the solder resist layer. Then, a resin-made wiring board sample with pins was prepared, and these were referred to as sample Nos. 1 to 5 (corresponding to the pin numbers). Then, each of the resin wiring board samples with pin No. The bonding strength of 30 pins each of 1 to 5 was confirmed.

(5) The bonding strength is the breaking load (kg) of the resin wiring board with pins when the pin is pulled in a direction inclined by 20 degrees with respect to the axial direction of the pins as shown in FIG. The measurement was performed 30 times for each of Samples 1 to 5. FIG. 8 shows the measurement result, the average value and the standard deviation of the measurement result, and FIG. 10 shows the average value and the standard deviation value of the measurement result. In the embodiment of the present invention, the criterion for the quality judgment is that the breaking load is 2.25 kg or more.

よ う As shown in FIG. 8, in the case of Sample No. 1 which is a comparative example, the average value of the bonding strength is lower than 2.25 kg which is a criterion for quality judgment. On the other hand, the sample No. In the cases of 2 to 5, the average value of the joining strength exceeds 2.25 kg. Therefore, it can be seen that the pin-attached resin-made wiring board sample having the pin whose diameter and thickness of the large-diameter portion are within the range of the present invention has preferable bonding strength as compared with the comparative example. However, the sample No. In some of the samples Nos. 2 and 3, the measured value was less than 2.25 kg, and the standard deviation was less than that of Sample No. 2. There is a tendency to be larger than 4 and 5.

Further, as described above, the form in which the resin circuit board with pins is damaged when an external force is applied to the pins is roughly classified into three types as shown in FIG. It is desirable to break. Therefore, in the above-described measurement, when the resin-made wiring board sample with pins was damaged, an observation was made as to how the sample was damaged. According to the results shown in FIG. No. 4, 80% or more of the sample No. In the case of Sample No. 5 which is a comparative example, only the pins were broken in 90% or more of Sample No. 5. In Sample No. 1, all of the samples were broken by solder. In sample No. 2, solder breakage accounted for the majority, and sample No. In No. 3, pin destruction is also seen, but solder destruction accounts for more than 50%. Therefore, the pin-attached resin wiring board sample having the pin whose diameter and thickness of the large-diameter portion fall within the scope of claim 3 of the present invention has a more desirable form of damage when destroyed than the other samples. It can be seen that there are many cases where only the pin is broken. Further, as shown in FIGS. Sample Nos. 4 and 5 are sample Nos. Compared with 1 to 3, the average value of the measurement results of the breaking load is large and the standard deviation is also a small value of about 60 to 80%. It can be seen that there is less variation in the breaking load as compared with the above, and it is advantageous to supply a stable product.

Now, the method of joining such pins 11 will be described in detail as follows. However, there is no difference from the conventional method for manufacturing a wiring board with pins, except that the pins W having a predetermined relation in the diameter W and the thickness T of the large diameter portion 112 of the pins 11 are joined.

(4) The internal wiring layer of the substrate 12 (before pin bonding) 12 before pin bonding is formed by a subtractive method using copper plating, a semi-additive method, a full-additive method, or the like. The resin insulating layer may be formed by laminating a resin filmed in advance on the surface of a core substrate or a lower substrate, or by applying a liquid resin by a roll coater or the like. The via formation of the resin insulating layer may be performed by laser processing if the material is a non-photosensitive resin, or may be formed by photolithography if the material is a photosensitive resin. May be dawn.

Thereafter, for example, a photosensitive solder resist layer is applied using a photolithography technique, and is exposed, developed, and cured using a mask pattern formed so that the center of the pin joint 15 is opened, and the solder resist layer 17 is formed. Form. After that, nickel plating and gold plating are applied to the exposed metal portion such as the pin joint 15, and the above-described amount of solder paste is printed on the pin joint 15 by screen printing.

On the other hand, a predetermined plate-like jig (not shown) provided with a number of small holes through which the pins 11 can be inserted, corresponding to the arrangement of the pin joint portions 15 of the substrate 12, is nickel-plated in the small holes. The gold-plated pin 11 is inserted with the large-diameter portion 112 facing upward. When the thickness of the gold plating layer on the surface of the pin 11 is 0.04 μm or more (0.3 μm in the present embodiment), the oxidation resistance and the reliability of connection with a socket or the like can be improved. Next, the substrate 12 is positioned and mounted thereon, and set so that the bonding surface 113 of the large-diameter portion of the pin 11 abuts on each of the pin bonding portions 112, and the solder paste is heated and melted. In this way, a large number of pins 11 are soldered at once to pin joints 112. Thus, the wiring board of the present invention is manufactured.

The large-diameter portion 112 of the pin 11 does not necessarily need to be formed of the same material as the pin body, and may be formed by reflowing (welding) a solder having a melting point that does not melt at the soldering temperature of the pin. Good. The large-diameter portion 112 of the pin 11 according to the present embodiment can be formed by pressing one end of a shaft material (wire material) with a mold having a planar shape in the axial direction.

The solder used for soldering the pins 11 may be selected from those that do not melt at the soldering temperature of electronic components such as ICs, depending on the material of the wiring board and the like. For example, in a resin wiring board, Pb-Sn solder (82Pb-10Sn-8Sb solder, 27Pb-73Sn eutectic solder, 50Pb-50Sn solder, etc.), Sn-Sb solder (95Sn-5Sb solder, etc.), Sn- Ag-based solder (96.5Sn-3.5Ag-based solder and the like) and the like. Among these, Sn-Sb-based solder is not preferable because it has poor wettability with a pin having a gold plating layer on its surface, and therefore prevents solder material from sticking to the pin when the pin is fixed to a substrate.

The planar shape of the pin joint 15 and the shape of the large-diameter portion 112 as viewed from the axial direction of the pin 11 are usually circular as in the present embodiment, but the shape is not limited to a circle. It is more preferable that the surface of the large diameter portion 112 forming the soldering surface is roughened so as to increase the bonding area.

In the above description, the wiring board with pins is embodied as a wiring board made of a PGA type epoxy resin, but the board of the present invention can be embodied regardless of the material of the board such as a polyimide resin, a BT resin, and a PPE resin. Not even. Further, the present invention can be applied regardless of a single-layer or multilayer structure. Further, the present invention is not limited to the PGA type, but can be broadly embodied in a wiring board in which flat pins are soldered to pin joints. The present invention is not limited to the above-described embodiment, and does not depart from the gist of the present invention. Can be embodied by appropriately changing the design.

Side view of resin wiring board 1 with pins according to the present invention Enlarged view of FIG. Enlarged view of FIG. Diagram showing the form of the solder layer Diagram showing the outline of load fracture measurement Types of damage to resin wiring boards with pins The figure showing the diameter and thickness of the large diameter part of the pin in an Example and a comparative example. Diagram showing measurement results of pin strength (joining strength) Diagram showing percentage of destruction mode Average value and standard deviation value of pin strength (joining strength) measurement results

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Resin wiring board with pin 11 Flat pin 12 Resin wiring board 111 Bar part of flat pin 112 Large diameter part of flat pin 15 Pin joint part 16 Solder layer 17 Solder resist layer

Claims (6)

A flat pin composed of a rod-shaped part having a diameter of 0.35 mm or less and a concentric plate-shaped large-diameter part formed at one end of the rod-shaped part and having a diameter larger than the rod-shaped part,
A pin-attached resin wiring board soldered at the large-diameter portion to a pin joint provided on a main surface of the board,
When the diameter of the rod portion of the flat pin is S and the diameter of the large diameter portion is W,
A ratio of the diameter of the rod portion to the diameter of the large diameter portion (W / S) is not less than 2.16 and not more than 2.67. When the thickness of the large diameter portion is T, a ratio (T / S) between the diameter of the rod portion and the thickness of the large diameter portion is 0.40 or more and 0.67 or less. The resin wiring board with pins according to claim 1, wherein The ratio (W / S) of the diameter of the rod portion to the diameter of the large diameter portion is 2.33 or more and 2.67 or less, and the ratio (T / S) of the diameter of the rod portion to the thickness of the large diameter portion. 3.) The resin wiring board with pins according to claim 2, wherein (b) is not less than 0.40 and not more than 0.54. The thickness of the solder layer formed based on the soldering is adjusted to be 0.30 mm or less in the thickness direction from the first main surface of the pin joint to the flat pin side. The resin wiring board with pins according to any one of claims 1 to 3, wherein the wiring board is made of resin. 5. The resin wiring board with pins according to claim 1, wherein the flat pins are made of a metal material containing at least copper. (6) The resin wiring board with pins according to any one of (1) to (5), wherein the diameter of the rod-shaped portion is 0.25 mm or more.