JP3037885B2 - Substrate for PGA type electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PGA (Pin Grid Array) type electronic component substrate,
A PGA-type electronic component substrate (hereinafter, referred to as a substrate) in which a large number of input / output terminal pins are provided upright on a main surface of a plastic substrate.
PGA type substrate, or simply referred to as a substrate).

[0002]

2. Description of the Related Art A PGA type substrate can take out input / output terminals in a plane, so that even if the number of terminals increases, a relatively sufficient pitch between terminals can be ensured without increasing the outer diameter of the package. Widely used from. This substrate is roughly classified into a ceramic type substrate made of a ceramic such as alumina and a plastic type substrate formed by laminating a glass-epoxy resin composite plate or the like.

[0003] Among them, the ceramic type PGA type substrate can be easily multi-layered, and a via hole for connecting wiring between upper and lower layers can be easily formed. Also, pins for input / output terminals (hereinafter, also simply referred to as pins) are also used as bonding pads formed on the main surface of the substrate, and pins having a head of a nail head type are attached to the end surfaces of the head. Can be joined easily and with high strength by abutting and brazing.

On the other hand, plastic type PG
The A-type substrate is formed by forming a copper wiring pattern by applying a resist or etching on a copper-clad resin plate (glass-epoxy resin composite plate, etc.) with a copper plate stuck on one side, or by drilling a hole in the resin plate. It is manufactured by laminating copper formed by plating or the like with an epoxy adhesive.
By the way, since the plastic type has low heat resistance of the substrate, the pins cannot be soldered as in the case of the ceramic type, and the soldering is performed with a relatively low melting point. However, if a pin having a nail head type head is soldered with its head in contact with the pad of the substrate, the bonding (bonding) strength is insufficient in practical use. Also,
In this case, the adhesion strength between the substrate and the pad (copper foil or copper plating) is as low as 1 to ² kgf / mm ² . For this reason, in the conventional general plastic type PGA type substrate, a through hole is formed in the substrate, the inner wall surface is electrically connected by copper plating or the like, and a pin is inserted through the through hole (press-fit). ) Or after that, the pins are fixed to the substrate by further impregnating with solder.

[0005]

As described above, the conventional plastic type PGA type substrate is provided with a through hole for fixing a pin due to its structure.
Since the circuit wiring cannot be formed above and below a certain portion of the pin, there is a problem that the density of the circuit (wiring) is reduced accordingly. In addition, since it is difficult to route the circuit because of the presence of the pins, there has been a problem that the demand for increasing the number of pins or increasing the density of the pins cannot be sufficiently satisfied. Further, there is a structure in which a hole fixed through a pin is formed in the middle of the substrate without being a through hole, and a pin is fitted into the hole (Japanese Patent Laid-Open No. 4-105351).
In that case, the strength tends to be insufficient, and the routing of the circuit is hindered because the pin is partially inserted.

The present invention has been made in view of the above-mentioned problems, and has been made in consideration of the excellent characteristics (low resistance wiring, low dielectric constant insulator, low cost, etc.) of a plastic type substrate, and a ceramic substrate. By realizing a structure that allows the pins to be joined without inserting the pins into the board and without lowering the joining strength as in the case of the type board, the density of circuit wiring formed in the board is reduced. It is an object of the present invention to provide a PGA-type electronic component substrate that can be made high and can sufficiently meet the demand for increasing the number of pins or increasing the density of pins.

[0007]

According to a first aspect of the present invention, there is provided a substrate for a PGA-type electronic component, comprising: a main surface of a plastic substrate for connecting pins for input / output terminals; A plurality of pads are formed on the pad, the pin having a head of a nail head type is held in electrical continuity through the head, and corresponds to the arrangement of the pin and A pin fixing plate having a through-hole formed so as to be able to penetrate the shaft portion and engage the head portion thereof, passes the shaft portion of the pin through the through-hole and engages the head portion of the pin. Then, the pin fixing plate is provided with a filling hole for filling with an adhesive, which is penetrated separately from the through hole, and is bonded to a main surface of the plastic substrate.

In the PGA-type electronic component substrate according to a second aspect of the present invention, the pin fixing plate is formed smaller than the outer shape of the main surface of the plastic substrate. In the above means, electrical conduction between the pad and the head of the pin may be maintained by soldering or bonding with a conductive adhesive, but is not limited thereto. In these means, the pin fixing plate may be adhered to the main surface of the plastic substrate using prepreg as an adhesive.

According to the configuration of the present invention, the electrical continuity between the pad and the head of the pin is maintained by soldering or bonding by a conductive adhesive, while the pin fixing plate is Adhered to the main surface of the board,
Since the head of the pin is engaged with the through hole of the pin fixing plate, the pin acts as a stopper when a tensile force is applied to the pin in the axial direction. The pin has a high joining strength despite being joined to the substrate in such a manner that it can withstand an external force (in the axial radius direction of the pin) even if it receives an external force. In particular, in the PGA-type electronic component substrate according to the first aspect, since the pin fixing plate has a filling hole separately from the through hole of the pin, the pin is press-fitted in the fixing plate in advance, and the pin is pressed into the pad under the state. In the joining method, an adhesive can be injected from the filling hole after the joining.

[0010]

The pin fixing plate has a predetermined electric insulating property,
Any material that maintains strength and heat resistance may be used, and examples thereof include glass BT (bismaleimide-triazine) resin, glass polyimide, glass phenol resin, and glass BCB. In such a composite material, paper or organic fiber can be used instead of glass (fiber). The pin fixing plate may be designed to have an appropriate thickness and an appropriate planar shape in consideration of the material thereof, the planar shape (size) of the substrate, and the like. In addition, the through-hole through which the shaft of the pin penetrates may be formed as long as it can penetrate the shaft and engage with the head of the pin, and may have an appropriate hole shape such as a circular hole. it can.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment A first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, reference numeral 1 denotes a PGA-type electronic component substrate (package main body) made of glass epoxy resin or the like, which has a substantially rectangular shape in a plan view, and one main surface thereof (the lower surface in FIG. 1).
2 is a pad for joining pins for input / output terminals (hereinafter referred to as a pad).
A large number of pads 3 are formed, and these pads 3 are connected to an IC chip to be mounted by wire bonding via circuit wiring formed in a cross section of the substrate 1 (not shown). Is formed. A pin 4 forming a nail head type is soldered to the pad 3 by abutting an end surface 5a of the head 5 thereof.
Electrical conduction between the pad 3 and the pin 4 is maintained via the solder (layer) 10.

On the other hand, the thin pin fixing plate 6 is bonded to the main surface 2 of the substrate 1 by an adhesive (layer) 7 so as to be engaged with the lower surface 5b of the head 5 of the pin 4 as described later. Have been. That is, in this example, the pin fixing plate 6 (hereinafter, also simply referred to as a fixing plate) provided with a large number of through holes 8 having a predetermined inner diameter in a predetermined arrangement corresponding to the arrangement of the pins 4 is used. The pin 4 is attached to the main surface 2 of the substrate 1 with an adhesive 7 through the shaft portion 4a of the pin 4. However, the fixing plate 6 in this example is a thin plate made of glass epoxy resin formed in a square slightly smaller than the one main surface 2 of the substrate 1, and the inner diameter (diameter) of the through hole 8 is the shaft portion 4 a of the pin 4. Outer diameter D1
(0.45 mm) and smaller than the outer diameter D2 (0.7 mm) of the head 5 of the pin 4 and is set to 0.5 mm in this example. Thus, in this example,
The head 5 is set so as to engage with 0.1 mm on one side by design.

The pin 4 used in this embodiment has a head 5
Is enlarged slightly larger than the diameter of the through hole 8, and when the pin 4 is pressed into the through hole 8 of the fixing plate 6, the expanded portion 4 b It is designed to bite and fix the wall (see FIG. 2). Then
A lower surface (a flange portion of the head) 5b of the head 5 of the pin 4 is
And the periphery of its head 5 is
It is filled with the filled and solidified adhesive 7, holds the pins 4, and adheres the fixing plate 6 to the substrate 1. In this embodiment, a large number of holes 9 for filling the adhesive 7 are provided in the fixing plate 6 in addition to the through holes 8 of the pins 4 in this example.

Here, one manufacturing method of the present embodiment shown in FIGS. 1 and 2 will be described with reference to FIGS. First, a large number of pads 3, 3 of a predetermined size formed on one main surface 2 of the substrate 1.
Solder cream (for example, Sn / Pb = 90/10)
Is printed in a predetermined amount (predetermined thickness). On the other hand, the above-mentioned fixing plate (resin plate) 6 is separately prepared, and the pins 4 are pressed into the predetermined through holes 8 by a press at a time until the head 5 is engaged (see FIG. 3). Next, as shown in FIG. 4, the fixing plate 6 into which the pins 4 are pressed is attached to the head 5 of each pin 4.
Is positioned and abutted so that the end face 5a of the substrate 1 faces each pad 3 of the substrate 1. Then, at a predetermined temperature (200 to 30)
(0 ° C.), for example, for 30 seconds to reflow the solder cream 10 and cool and solidify it. As a result, the pins 4 are soldered to the pads 3 to maintain electrical continuity.

After the soldering, a minute gap k is formed between the main surface 2 of the substrate 1 and the fixing plate 6, and this gap k is a gap between the outer edges of the substrate 1 and the fixing plate 6. Alternatively, a thermosetting resin-based adhesive such as an epoxy resin is injected (press-fitted) and filled as an adhesive from a filling hole 9 formed in the fixing plate 6. In this filling, the resin is filled until the surplus resin comes out from the outer edge portion of the substrate 1 or another filling hole 9. Thereafter, the adhesive is heated at a predetermined temperature for a predetermined time (for example, about 24 hours at room temperature or about 5 hours at 150 ° C.) to cure the adhesive,
The fixing plate 6 is bonded to the main surface 2 of the substrate 1.

1 and FIG. 2, the outer periphery of the head 5 of the pin 4 is solidified by the adhesive 7 and the head 5 of the pin 4 Since the lower surface 5b is engaged with the peripheral surface 8a of the through hole 8, the bonding strength of the pin, which is insufficient only by soldering, is kept high. By the way, according to the pin tensile test, in the case of only soldering, the end face (soldered portion) of the head of the pin separated from the pad at about 2 to 3 kgf. 8kgf without any separation
Thus, the shaft was cut in the middle.

As described above, in this embodiment, the plastic P
Although the pin 4 is a GA package, the pins 4 are joined to the substrate 1 in an abutting state without being penetrated or fitted into the substrate 1, so that wiring is provided inside the cross section of the PGA type substrate in the same manner as the ceramic type PGA type substrate. Can be routed,
It is possible to increase the density of wiring and increase the number of pins to the same extent.

The above structure can be manufactured without press-fitting the pins into the fixing plate in advance (see FIGS. 5 to 7). That is, first, a pin 4 is applied to the pad 3 on which the solder cream 10 is applied and formed by using a predetermined jig.
Are joined by reflow while holding the end face of the head 5 in an upright state (see FIG. 5). Then, an adhesive 17 such as an epoxy resin is applied to the main surface 2 side (the upper surface in FIG. 6) of the substrate 1 to which the pins 4 are joined, and thereafter, as shown in FIG. The pin 17 is put on the main surface 2 of the substrate 1 through the pins 4 and the fixing plate 6 is pressed with a predetermined load W as shown in FIG. What is necessary is just to make it adhere | attach. According to such a manufacturing method, when the pins 4 are joined (soldered) (the state shown in FIG. 5), there is no fixing plate.
Flux cleaning becomes easy. In this manufacturing method, an adhesive may be applied to the fixing plate.

In the above-mentioned manufacturing method, solder cream is formed on the pads 3 of the substrate 1 for joining (soldering) the pins. However, a solder clad may be formed on the end face of the head 5 of the pins 4. Good. The connection between the head of the pin and the pad only needs to maintain electrical continuity. Therefore, instead of solder, an Au-Sn paste that can be fused under almost the same conditions as above is applied to the pad. Is also good. Further, since it is only necessary to maintain the electrical continuity, a conductive (resin) adhesive may be applied on the pad or on the end face of the head of the pin, and then bonded.

If the conductive adhesive is used to maintain electrical continuity between the pad and the pin, the bonding can be performed by holding the pad at, for example, 150 ° C. for about one hour. Use a material whose temperature is lower than the heat resistant temperature of the agent. When a conductive adhesive is used, a reflow process is not required unlike soldering or the like, so that manufacturing is facilitated. Even when a conductive adhesive is used, the pins are press-fitted into the fixing plate in advance, and are joined to the pads (maintaining continuity).
Then, as described above, an adhesive may be filled from a filling hole or the like and bonded, or a pin may be bonded to a pad (conduction is maintained) and then a fixing plate may be bonded later. That is, the pins and pads in the PGA type substrate according to the present invention need only maintain electrical continuity, and are not limited to soldering or bonding with a conductive adhesive.

Further, in the PGA type substrate having the above structure, the bonding means (adhesive) for bonding the fixing plate to the substrate is provided with a through hole (having a hole diameter substantially equal to the diameter of the pin head) corresponding to the pin arrangement. ) (A plate obtained by impregnating glass cloth fibers or the like with an epoxy resin or the like and semi-curing) can also be used.

Here, a manufacturing method using a prepreg will be described with reference to FIGS. The first example is
As described above, first, the pins 4 are soldered to the pads 3 of the substrate 1 or bonded with the conductive adhesive 10. Then, FIG.
As shown in the figure, a predetermined thickness (for example, 50 to 100 μm)
m), the prepreg 27 having a through-hole 28 having substantially the same diameter as the diameter of the head 5 of the pin 4 at a position corresponding to the arrangement of the pin 4, as in the case of the fixing plate 6. And the through-hole 28 of the prepreg 27 and the through-hole 8 of the fixing plate 6 face each other so as to match the pin 4. (See FIG. 9). Then, pressure is applied at a predetermined temperature (150 to 200 ° C.) for a predetermined time (1.5 to 2.5 hours) at a predetermined pressure (20 to 70 kgf / cm ² ) to cure the prepreg 27. By doing so, the substrate 1 and the fixing plate 6 are adhered to each other using the prepreg 27 as an adhesive, and the pin 4 has its head 5 at the through hole 2 of the fixing plate 6.
8 and is fixed in a state of being engaged with the peripheral surface. The filling hole 9 of the fixing plate 6 becomes unnecessary when pressure bonding is performed by a vacuum press.

[0024]

Next, the second case in which a prepreg is used will be described.
Will be described with reference to FIGS. 10 and 11. According to this method, the pins 4 are inserted into the through holes 8 of the fixing plate 6 at a time (press-fitting) to the heads 5 of the prepregs 27 without previously joining the pins to the pads 3 of the substrate 1. The conductive adhesive 30 is filled or buried in the through hole 28 for the pin formed in the above. Then, as shown in FIG. 11, the fixing plate 6 into which the pins 4 are inserted via the prepreg 27 is moved to the portion of the conductive adhesive 30 in which the heads 5 of the pins 4 are filled in the through holes of the prepreg. And pad 3 so as to correspond. Then, the prepreg and the conductive adhesive are cured by pressing under a predetermined load W at a predetermined temperature. Then, the pad 3 and the head 5 of the pin 4 are bonded with the conductive adhesive 30 to maintain electrical continuity. A prepreg 27 is formed between the main surface 2 of the substrate 1 and the fixing plate 6.
The head 5 of the pin 4 is engaged with and fixed to the peripheral surface of the through hole of the fixing plate 6, so that a desired structure similar to that shown in FIG. 9 can be obtained.

The size of the through-hole 28 of the prepreg 27 and the amount of the conductive adhesive 30 to be embedded are determined by ensuring that the pad 3 and the pin 4 facing each other after the bonding are electrically insulated from each other. Thus, it is only necessary to maintain the electrical continuity, and it may be set appropriately. Therefore, prepreg 2
The size of the through hole 28 provided in the nozzle 7 may be smaller than the diameter of the pin head 5 and larger than the diameter of the shaft portion, and may be used in the same manner as described above. In this case, by making the material and thickness of the prepreg 27 appropriate, the prepreg 2
7 is deformed and hardened. Therefore, the peripheral surface 8a of the through hole of the fixing plate 6 and the head 5 of the pin
The fixing plate 6 is adhered to the main surface 2 of the substrate 1 while being engaged through.

In each of the above-described examples, the pad 3 and the pin 4 are connected with solder or a conductive adhesive to maintain electrical continuity. The head 5 is brought into close contact with the head 5 to maintain electrical continuity, while the joint strength between the two is such that the head 5 of the pin 4 is
May be obtained by engaging with. It is preferable that the end face 5a of the head 5 of the pin is roughened, knurled, or provided with concavities and convexities such as a conical shape, because electrical conductivity with the conductive adhesive 30 and the pad 3 is easily maintained.

[0028]

[0029]

[0030]

[0031]

According to the present invention, the excellent characteristics (low resistance wiring, low dielectric constant insulator,
It is possible to realize a structure in which the pins can be joined without inserting the pins into the substrate as in the case of the ceramic type substrate, and without lowering the joining strength, while taking advantage of low cost, etc.). Therefore, even though it is a plastic type PGA type electronic component substrate, the density of circuit wiring formed in the substrate can be increased, and the number of pins or the density of pins can be increased. In the case where the filling hole is provided separately from the through hole of the pin, in a manufacturing method in which the pin is pressed into the fixing plate in advance and the pin is bonded to the pad under the state, the fixing plate is bonded after the bonding. At this time, an adhesive can be injected from the filling hole.

[Brief description of the drawings]

FIG. 1 is a central longitudinal sectional front view showing a first embodiment of a PGA type electronic component substrate according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is an explanatory view of a manufacturing process of the PGA-type electronic component substrate of FIG. 1, which is a longitudinal sectional front view at the center in which pins are pressed into a pin fixing plate to face pads of the substrate.

FIG. 4 is a front view of the central longitudinal section in a state where the heads of the pins are soldered to pads of a substrate after the step shown in FIG. 3;

FIG. 5 is an explanatory view of another manufacturing method of the PGA type electronic component substrate of FIG. 1, and is a longitudinal sectional front view of the center in a state where pins are soldered to pads of the substrate via its heads.

FIG. 6 is a central longitudinal sectional front view illustrating a state in which an adhesive is applied to the main surface side of the substrate after the step shown in FIG. 5 and a fixing plate is put on the main surface of the substrate by passing pins through through holes.

FIG. 7 is a front view of the central longitudinal section in a state where a fixing plate is adhered to the main surface of the substrate in the step shown in FIG. 6;

FIG. 8 is a view for explaining a manufacturing method in which a prepreg is used as an adhesive means for adhering a pin fixing plate to a substrate, wherein pins are adhered to pads of the substrate, and the prepreg is interposed between the substrate and the fixing plate. FIG. 2 is a front view of the central vertical section in a state where the positioning is performed.

FIG. 9 is a front view in a central longitudinal section in a state where a pin fixing plate is adhered to a substrate after the step shown in FIG.

FIG. 10 is a view for explaining another manufacturing method when a prepreg is used as an adhesion means for adhering the pin fixing plate to the substrate, wherein the pin fixing plate into which the pins are pressed is opposed to the substrate via the prepreg. The center longitudinal section front view of a state.

11 is a front view of the central longitudinal section in a state where the pin fixing plate into which the pins have been pressed is brought into contact with the substrate after the step shown in FIG. 10;

[Explanation of symbols]

 Reference Signs List 1 plastic substrate 2 main surface of substrate 3 pad 4 pin for input / output terminal 4a shaft of input / output terminal pin 5 head of input / output terminal pin 6 pin fixing plate 7,17 adhesive 8 pin fixing Plate through-hole 27 Pre-preg (adhesive)

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 23/12 H01L 23/50

Claims (3)

(57) [Claims] 1. A plurality of pads for joining pins for input / output terminals are formed on a main surface of a plastic substrate, and the pins having a head of a nail head type are formed on the pads via the heads. A pin fixing plate provided with a through hole which is maintained in electrical continuity, and is formed so as to correspond to the arrangement of the pin, to penetrate the shaft of the pin, and to engage the head thereof. Is passed through the through-hole of the pin, and the head of the pin is engaged with the pin to adhere to the main surface of the plastic substrate, and the pin fixing plate is penetrated separately from the through-hole. A substrate for a PGA-type electronic component, comprising a filling hole for filling an adhesive. 2. The PGA type electronic component substrate according to claim 1, wherein said pin fixing plate is formed smaller than an outer shape of a main surface of said plastic substrate. 3. The P according to claim 1, wherein the electrical continuity between the pad and the head of the pin is maintained by soldering or bonding with a conductive adhesive.
GA type electronic component substrate.