JP2004363128A - Resin wiring board with pin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin wiring board with pin in which connection pins are soldered to the pin-pad conductors of the resin wiring board and which is improved in the reliability of electrical characteristics. <P>SOLUTION: The resin wiring board 1 with pin is provided with connections 6 (composed of via conductors) which electrically connect lid-like conductor layers 4 formed on a core substrate 2 having through-hole conductors 22 and filling materials 23 in through holes 21 to the pin-pad conductors 5 provided with connection pins 9 which can be connected to the connection terminals of an external substrate. The resin wiring board is characterised in that the center axial lines 901 of the connection pins 9 not positioned on the through holes 21 when the penetrated directions of the through hole 21 are the directions of the center axial directions of the through holes 21. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
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 connection pins (connection terminals) are soldered to a predetermined number of pin pad conductors formed on the main surface of the wiring board.
[0002]
[Prior art]
The PGA type wiring board has a predetermined number of pad-like electrodes used for mounting electronic components such as LSIs and IC chips on one main surface, and a socket provided on a motherboard or the like on the other main surface. It has a predetermined number of pin pad conductors for connection to the connector and connection pins (connection terminals) soldered thereto. In this type of resin wiring board with pins, the size and the number of connection terminals (number of pins) are reduced in order to increase the integration and density of electronic components such as LSIs, IC chips or chip capacitors to be mounted. Are increasing.
[0003]
As shown in FIG. 2A, the internal structure of such a resin wiring board with pins includes a core substrate having a through-hole conductor and a filler in a through-hole formed in an insulating substrate; The cover-like conductor layer, the resin layer, the pin pad conductor, and the connection pin (connection terminal) formed on the top are buried in the resin layer so as to conduct the through-hole conductor and the pin pad conductor (connection pin soldered thereto). And a via conductor.
[0004]
[Patent Document 1]
JP 2003-8219 (see FIG. 1)
[0005]
[Problems to be solved by the invention]
In the resin wiring board with pins as described above, the following problem arises in the course of the thermal cycle performed during manufacturing or the like. A metal layer that penetrates through a thickness direction is formed at a predetermined position of an insulating material substrate made of resin or the like in order to conduct between two main surfaces on a core substrate serving as a core of the resin wiring substrate. Since the metal and the resin have different coefficients of thermal expansion, the expansion / contraction in the thickness direction of the core substrate due to the heat cycle is biased depending on the position. For this reason, in the layers laminated on the core substrate, the force applied due to the expansion / contraction of the core substrate becomes uneven, and as a result, cracks occur at the joint surfaces of the via conductors, and the pin pads are removed from the through-hole conductors. There has been a problem that the electrical connection to the conductor (and the connection pins soldered thereto) is easily cut off. This leads to failure to maintain the quality such as electrical characteristics required for the resin wiring board.
[0006]
The present invention has been made in view of the above problems. An object of the present invention is to provide a resin wiring board with pins having high reliability in electrical characteristics for a resin wiring board with pins in which connection pins are soldered to pin pad conductors of the resin wiring board.
[0007]
Means for Solving the Problems and Functions / Effects of the Invention
In order to solve the above problems, in the resin wiring board with pins of the present invention,
A through-hole formed through the insulating substrate, and a substantially cylindrical through-hole conductor formed on the inner peripheral surface of the through-hole, and a filler filled in a hollow portion of the through-hole conductor. A core substrate having
On at least one main surface of the core substrate, a lid-like conductor layer formed to include an end surface of the through-hole, and conducting with the through-hole conductor,
A plurality of resin layers formed on the lid-like conductor layer,
A pin pad conductor formed on the plurality of resin layers,
A connection pin comprising a rod-shaped part and a flange formed at one end of the rod-shaped part, soldered on the pin pad conductor at the flange, and connectable to a connection terminal of an external board,
A connection portion formed of a via conductor embedded in each of the plurality of resin layers so as to conduct the lid-shaped conductor layer and the pin pad conductor,
A resin wiring board with pins comprising:
The connection portion is configured by stacked vias connected so that each of the via conductors formed of filled vias are connected in a substantially concentric manner,
When the penetration direction of the through hole is the central axis direction, the central axis of the stacked via (or the connection pin and the stacked via) is not located on the through hole.
[0008]
Generally, the thermal expansion coefficient of a resin material is larger than that of a metal material. When the resin-made wiring board 1 with pins as shown in FIG. 2A is heated, a substantially cylindrical through-hole conductor 22 (metal material) constituting the core substrate 2 and a hollow portion of the through-hole conductor 22 are formed. The filled filler 23 (resin material) and the insulating substrate material 24 having the through holes 21 (resin material: located around the through-hole conductors 22) expand in the thickness direction. At this time, as shown in FIG. 2B, the expansion of the through-hole conductor 21 (metal material) is smaller than that of the surrounding resin materials 23 and 24. In addition, a bias is generated in the force applied to the lid-like conductor layer 4, the resin layer 3, and the pin pad conductor 5. Specifically, the applied force is smaller only in the vicinity of the through-hole conductor 22 than in the surroundings, so that a force is generated in the vicinity of the through-hole conductor 22 as if the force were lowered downward. When the resin wiring board with pins 1 is cooled, the opposite phenomenon occurs. As shown in FIG. 2C, the pin-like resin wiring board 22 is pushed upward in the vicinity of the through-hole conductor 22. Force is generated. Therefore, if the via conductors 61 and 62 formed of filled vias, the center axes of the pin pad conductors 5 and the connection pins 9 are provided on the through-hole conductors 22, the lid conductors are easily affected by pulling down / pushing up from the core substrate 2. Excessive stress concentration occurs between the layer 4 and the via conductor 61, between the via conductors (between the via conductors 61 and 62), and between the via conductor 62 and the pin pad conductor 5, and their connection is easily cut off. turn into.
[0009]
Therefore, as described above, the stacked via connected to the lid-like conductor layer on the through hole, and the center axis of the connection pin soldered to the pin pad conductor are arranged so as not to be located on the through hole, respectively. It is possible to reduce the influence of the pulling / pushing up from the core substrate as described above.
[0010]
Note that the central axis here is the same direction as the direction of penetration of the through-hole, and the through-hole, the stacked via, and the connection pin (the center axis of the connection pin is defined by a rod-shaped portion) are respectively It passes through the center position in a substantially circular projection image projected on a plane perpendicular to the penetration direction.
[0011]
Further, in the present invention, it is conceivable that an error occurs in the position where the stacked via or the connection pin is arranged due to manufacturing reasons or the like. Therefore, an error such that the amount of deviation between the center axes becomes a distance of 0 μm or more and 30 μm or less. Shall be allowed.
[0012]
In the present invention, it is preferable that the diameter of the through hole is 50 μm or more and 400 μm or less. When the diameter of the through-hole is excessively small (less than 50 μm), as shown in FIG. 3, the expansion of the core substrate 2, the heat is applied to the end surface of the filler 23 (the surface where the filler 23 contacts the lid-shaped conductor layer 4). The proportion of the portion where the expansion is hindered by the lid-like conductor layer 4 connected to the through-hole conductor 22 having a small expansion coefficient (near the periphery of the end face of the filler 23) increases. In this case, the expansion of the filler 23 concentrates in the vicinity of the center axis of the through-hole 21, and excessive stress concentration due to thrust up near the center tends to occur. Arrangement near the axis may be disadvantageous. In order to avoid such an effect, the diameter of the through hole needs to be 50 μm or more. Further, when the diameter of the through hole exceeds 400 μm, it may be disadvantageous for high integration and high density of the wiring board. More preferably, the diameter of the through hole is 50 μm or more and 300 μm or less.
[0013]
When the diameter of the through hole is in the above range, it is preferable that the average wall thickness of the substantially cylindrical through hole conductor is 5 μm or more and 50 μm or less. If the average wall thickness is excessively thick, the expansion of the filler inside the through-hole conductor concentrates near the central axis of the through-hole as described above, and excessive stress concentration due to thrust may occur, so the upper limit value is set. Is set to 50 μm. The lower limit is not particularly limited. However, if the thickness is excessively small, conduction may not be obtained. More preferably, the average wall thickness of the substantially cylindrical through-hole conductor is 5 μm or more and 30 μm or less.
[0014]
Further, when the through-hole or the through-hole conductor is in the above range, the center axis of the stacked via is located at a distance of 5 μm or more and 600 μm or less from the outer edge of the through-hole conductor, and the center axis of the connection pin is It is preferable to be arranged at a position having a distance of 5 μm or more and 600 μm or less from the outer edge. In both cases, if the distance is smaller than the lower limit value, the center axis is too close to the through-hole conductor position where the influence of the pull-down / push-up from the core substrate is large as described above, so that the influence is easily affected. If the value is larger than the above value, it may be disadvantageous for high integration and high density of the wiring board. More preferably, the distance of the center axis of the stacked via from the outer edge of the through-hole conductor is 30 μm or more and 500 μm or less, and the distance of the center axis of the connection pin from the outer edge of the through-hole conductor is 30 μm or more and 500 μm or less.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a resin wiring board with pins of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a resin wiring board 1 with pins. The resin wiring board 1 with pins has a rectangular shape in a plan view (for example, each of 50 mm in length and width, 1 mm in thickness), and a predetermined number of connection pins 9 which can be connected to connection terminals of an external board such as a motherboard are provided in the figure. It is the figure which expanded a part of internal structure of the main surface side performed. Although not shown, a predetermined number of electrodes for connecting a semiconductor integrated circuit element IC to be mounted are formed on the opposite main surface side, and the internal wiring layers of each layer and each internal wiring layer are formed therein. Via conductors for connecting them are formed.
[0016]
The core substrate 2 has a through hole 21 having a diameter of about 300 μm formed by penetrating through a substrate material 24 containing BT resin as a main component and having a thickness of about 0.8 mm at an interval of about 1.3 mm. A substantially cylindrical (wall thickness of about 18 μm) through-hole conductor 22 mainly composed of copper and a filler 23 mainly composed of epoxy resin filled in a hollow portion of the through-hole conductor 22 formed on the peripheral surface; Is provided. The core substrate 2 may have a conductor layer or a via conductor formed therein. The lid-shaped conductor layer 4 is formed on the surface of the core substrate 2 so as to include the end face of the through hole 21, and is electrically connected to the through hole conductor 22. The lid-shaped conductor layer 4 is, for example, a column having a diameter of about 350 μm and a thickness of about 35 μm, and is arranged so that the central axis thereof coincides with the central axis 201 of the through-hole 21 in the through direction. Since the diameter is larger than the diameter of the through hole (about 300 μm), the substrate material 24 is covered by about 25 μm from the outer edge of the through hole 21.
[0017]
On such a core substrate 2, a plurality of resins having a thickness of about 50 μm (about 25 μm per layer) are composed of two layers, a lower resin layer 31 and an upper resin layer 32, which are mainly composed of epoxy resin. Layer 3 is formed. In the present embodiment, the plurality of resin layers 3 are composed of two layers, but may be three or more without being limited to two layers. On the upper resin layer 32, a predetermined number of cylindrical conductor layers mainly composed of copper are formed at intervals of about 1.3 mm, and the surface thereof is nickel-plated and gold-plated. The pin pad conductor 5 is formed. The pin pad conductor 5 has a diameter of about 800 μm and a thickness of about 15 μm. The position of the pin pad conductor 5 is within a range where the pin pad conductor 5 can be connected to the upper filled via 62 of the stacked via (connecting portion) 6 described later, and the connection pin 9 installed substantially concentrically on the upper main surface 51 is described later. It is a range that can be installed under the conditions that meet the requirements.
[0018]
In addition, on the upper resin layer 32, a solder resist layer 7 having a thickness of about 25 μm is formed on portions where the pin pad conductors 5 are not arranged. In the present embodiment, the solder resist layer 7 is formed so as to cover the periphery of the upper main surface 51 of the pin pad conductor 5 with a predetermined width, and to form a portion concentrically exposed from the center of the upper main surface 51 of the pin pad conductor 5. Have been. Incidentally, in this example, the diameter of the exposed portion (the opening of the solder resist layer 7, that is, the portion of the upper main surface 51 of the pin pad conductor 5 that is not covered by the solder resist layer 7), that is, the diameter of the upper main surface 51 of the pin pad conductor 5. The diameter of the soldering surface is set to about 650 μm.
[0019]
The connection pin 9 is provided on the upper main surface 51 of the pin pad conductor 5, and a position where the center axis 901 (defined by the rod portion 91 of the connection pin 9) is not located on the through hole 21, specifically, Is located at a distance L from the outer edge of the through hole 21 to about 300 μm. The connecting pin 9 is made of an alloy containing copper as a main component, for example, a copper alloy such as Alloy 194 (CDA alloy C19400 (based on ASTM B465)) or the like, and is a round bar-shaped rod having a circular cross section (about 0.30 mm in diameter). It has a nail shape of 91 (total length of about 2 mm). At one end thereof, a circular flange 92 protruding radially is provided concentrically, and the connection pin 9 is installed by being soldered to the flange 92 with an appropriate amount of known solder. (Japanese Patent No. 3160583). A layer of solder formed by soldering is called a solder layer 8. However, of the flange portion 92, the joint surface 921 facing the upper main surface 51 of the pin pad conductor 5 is formed in a spherical shape that is entirely convex, and concentrically contacts the upper main surface 51 of the pin pad conductor 5. Placed in 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%). In the present embodiment, a spherical spherical pin is used as the connection pin 9 in which the entire joint surface 921 facing the upper main surface 51 of the pin pad conductor 5 is convex. However, the present invention is not limited to this. Instead, a flat pin having a flat bonding surface facing the upper main surface 51 of the pin pad conductor 5 may be used.
[0020]
The amount of solder forming the solder layer 8 is appropriately selected so that the connection pin 9 can be fixed at the flange 92. Further, in order to fix the connection pins 9 by melting the solder, the solder layer 8 has a form that spreads toward the surface of the upper main surface 51 of the pin pad conductor 5. However, the height of the solder layer 8 from the upper main surface 51 of the pin pad conductor 5 after formation is desirably about 300 μm, and the spread of the solder layer 8 spreads over the periphery of the upper main surface 51 of the pin pad conductor 5. It is desirable not to exceed the end position.
[0021]
Filled vias 61 and 62 are buried in each of the plurality of resin layers 3 (the lower resin layer 31 and the upper resin layer 32). What is buried in 32 is referred to as 62). The filled via is formed by filling a via hole formed through a resin layer with a metal material containing copper as a main component, and has a maximum diameter of, for example, about 85 μm. The filled vias 61 and 62 are connected substantially concentrically to form a stacked via (connection portion) 6, and the lower filled via 61 further includes an upper main surface 41 of the lid-like conductor layer 4 below the lower via and an upper filled via 62. Is electrically connected between the lid-shaped conductor layer 4 and the pin pad conductor 5 by being connected to the lower main surface 52 of the pin pad conductor 5 thereon. The center axis 601 of the stacked via (connecting portion) 6 has a distance VL from the outside of the through hole 21, specifically, the outer edge of the through hole 21 of about 50 μm so as to be hardly affected by the contraction / expansion of the core substrate 2. It is arranged so that it becomes. Further, in the present embodiment, the center axis 601 of the stacked via (connection part) 6 and the center axis 901 of the connection pin 9 are arranged so as to coincide with each other. However, the present invention is not limited to this, and the respective distances PL and VL are provided. Is within the above-mentioned range, and the positional relationship is such that the stacked via (connecting portion) 6 and the pin pad conductor 5 can be connected.
[0022]
【Example】
Here, specific examples of the resin wiring board with pins of the present invention will be described together with comparative examples. The above embodiment (FIG. 1) is taken as an example, and in the comparative example, a via conductor formed of a filled via as shown in FIG. 2A and a pin pad conductor are arranged on the through-hole conductor with their central axes aligned. Form.
[0023]
Regarding Examples and Comparative Examples, a heat cycle (10 minutes per cycle) in which heating and cooling are repeated between -55 ° C. and 125 ° C. is performed before (1), after (2) 100 cycles, and after (3) 500 Three types of samples after the cycle were prepared, and a cross section SEM (Scanning Electron Microscope) was observed to evaluate the crack generation rate.
[0024]
According to the evaluation results, in Examples, (1) before heat cycling, (2) after 100 cycles, and (3) all samples after 500 cycles, no abnormalities such as cracks were observed in the SEM images. In the examples, cracks were observed in about half or more of the samples after (2) 100 cycles and (3) 500 cycles. (1) In the sample before the thermal cycle, cracks were already observed in some samples. This is considered to be due to heat treatment at the time of solder pin installation.
[Brief description of the drawings]
FIG. 1 is a view showing a part of the internal structure of a resin wiring board with pins of the present invention. FIG. 2 is a view showing the influence of expansion / contraction of a core board. FIG. 3 is a view showing a core having a small through-hole diameter. Expansion / contraction of substrate [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pin-made resin wiring board 2 Core board 21 Through hole 22 Through hole conductor 23 Filler 3 Plural resin layers 31 Lower resin layer 32 Upper resin layer 4 Cover conductor layer 5 Pin pad conductor 6 Stacked via (connection part)
61 Lower Filled Via 62 Upper Filled Via 7 Solder Resist Layer 8 Solder Layer 9 Connection Pin

Claims (2)

A through-hole formed through the insulating substrate, and a substantially cylindrical through-hole conductor formed on the inner peripheral surface of the through-hole, and a filler filled in a hollow portion of the through-hole conductor. A core substrate having
On at least one main surface of the core substrate, a lid-like conductor layer formed to include an end surface of the through-hole, and conducting with the through-hole conductor,
A plurality of resin layers formed on the lid-like conductor layer,
A pin pad conductor formed on the plurality of resin layers,
A connection pin comprising a rod-shaped part and a flange formed at one end of the rod-shaped part, soldered on the pin pad conductor at the flange, and connectable to a connection terminal of an external board,
A connection portion formed of a via conductor embedded in each of the plurality of resin layers so as to conduct the lid-shaped conductor layer and the pin pad conductor,
A resin wiring board with pins comprising:
The connection portion is configured by stacked vias connected so that each of the via conductors formed of filled vias are connected in a substantially concentric manner,
In the case where the through-hole direction of the through hole is the central axis direction, the central axis line of the stacked via is not located on the through hole. 2. The resin wiring board with pins according to claim 1, wherein a center axis of the connection pin is not located on the through hole. 3.

Images