JPH0669073B2 - Leadless parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] Side wall electrodes connected to a circuit element are formed in side wall recesses formed in parallel with each other on the side wall of a carrier, the side wall recesses being in communication with the side wall recesses at the periphery of the bottom surface of the carrier. By providing a leadless component in which a bottom recess having an arcuate shape in side view is provided and a bottom electrode connected to the sidewall electrode is formed on the inner surface of the bottom recess, when soldering and mounting on a pad of a circuit board, the solder causes a bottom phenomenon due to a capillary phenomenon. Ascends to the recess and adheres to the bottom electrode.

Therefore, the strength of soldering is high, and there is no risk of short-circuiting between adjacent board pads and electrodes.

[Industrial application field]

The present invention relates to an improvement of a leadless component in which a semiconductor chip such as an IC, an LSI or the like, or a circuit element or the like (hereinafter abbreviated as circuit element) of a hybrid integrated circuit is mounted on a carrier made of ceramic.

A leadless component in which circuit elements are mounted on a carrier made of a small box-shaped ceramic and electrodes made of a conductive film are provided on the side wall and bottom surface of the carrier are small in size and can be mounted at high density on a circuit board. Not only that, but since there are no leads, there is an advantage that stray capacitance does not occur when mounted.

However, on the other hand, with the large number of electrodes in the circuit element,
In such a leadless component, a large number of electrodes adjacent to each other are formed on the side wall and the bottom surface of the chip carrier.

For this reason, leadless semiconductor components are required to have a structure in which there is no risk of short-circuiting between electrodes during mounting by soldering and the soldering strength is strong.

[Conventional technology]

A conventional leadless component will be described with reference to FIGS. 3 and 4.

FIG. 3 is a block diagram of a conventional example, (a) before mounting, (b)
FIG. 4 is a perspective view after mounting, FIG. 4 is a partially cutaway side view of a conventional example, (a) is a view at the time of mounting, and (b) is a view after mounting.

In FIG. 3, a small rectangular plate-shaped carrier 2 made of ceramics such as alumina has a stepped rectangular concave portion 3 at the center.
Is formed, and the circuit element 1 which is a semiconductor chip such as an LSI or IC is mounted in the stepped rectangular recess 3.

On the step end surface 4 of the stepped rectangular recess 3 parallel to the bottom surface 23 of the carrier 2, side wall recesses, which will be described later, are arranged side by side on the side wall of the carrier 2 radially in a direction orthogonal to each side of the stepped rectangular recess 3.
An electrode pattern 5 made of a desired number of metal conductor films, each of which communicates with 22, is formed.

Then, a connecting wire made of, for example, a gold wire is wire-bonded, and the inner end portion of the electrode pattern 5 and the semiconductor chip 1 are connected.
Of the respective electrodes are connected.

On each outer side wall 21 of the carrier 2, side wall recesses 22 which are perpendicular to the bottom surface 23 and are arcuate in plan view are provided in parallel, and the inner surface of each side wall recess 22 is perpendicular to the outer end surface of the electrode pattern 5. Sidewall electrodes 6 made of a metal conductor film, which are connected to each other, are formed. In addition, on the periphery of the bottom surface 23 of the carrier 2,
A rectangular strip-shaped bottom pad 7 made of a metal conductor film and connected to each side wall electrode 6 is formed.

Furthermore, a cover 9 made of a ceramic plate or a metal plate is adhered to the open upper end surface of the carrier 2 to seal the semiconductor chip 1 in the stepped rectangular recess 3.

On the other hand, a desired conductor pattern is formed on the upper surface of the circuit board 30 made of a ceramic plate, and the end portions of each conductor pattern correspond to the bottom surface pads 7 of the carrier 2 and are square-shaped board pads 31. Are juxtaposed.

In order to manufacture the above-mentioned carrier 2, desired rectangular plate-shaped and frame plate-shaped ceramic plates are laminated in the state of a green sheet to form a bottom hole portion of the stepped rectangular concave portion 3, A paste such as molybdenum is screen-printed on the end face 4 of the end face to provide a base film for the electrode pattern 5, and a frame plate-shaped ceramic plate is laminated on the upper face in the state of a green sheet to form a stepped rectangular recess. 3 to form the shape part.

Next, after firing, the carrier 2 is hardened and integrated, the sidewall recess 22 is provided by laser processing or the like, and finished into a desired shape. After that, the base layer of the side wall electrodes 6 and the bottom pad 7 is screen-printed with paste of molybdenum or the like and baked, and the exposed surface of the electrode pattern 5 and the top surface of the base layer of the side wall electrodes 6 and the bottom pad 7 are plated with gold or the like. , The electrode pattern 5, the sidewall electrode 6, and the bottom pad 7 are completed.

The leadless component can be easily manufactured as described above.

To mount the leadless component as described above on the circuit board 30 by soldering, a solder paste is screen-printed on the upper surface of the board pad 31, for example, as shown in FIG. The pads 7 are aligned, the leadless component is temporarily installed on the circuit board 30, and the circuit board 30 is placed in an infrared heating furnace or the like for heating.

When heated, as shown in FIG. 4 (b), the solder paste reflows and adheres to the bottom surface pad 7, and at the same time, the molten solder rises to the side wall recess 22 due to the capillary phenomenon and adheres to the side wall electrode 6 and solder. It becomes 10 and sticks.

[Problems to be solved by the invention]

However, in the conventional leadless component described above, the size of each bottom pad 7 is limited due to the large number of bottom pads 7 arranged side by side on the periphery of the bottom surface 23. Therefore, the fixing surface of the solder 10 is relatively small, the soldering strength becomes weak, and the solder 10 may crack due to vibration of the circuit board, thermal expansion due to the operation of the semiconductor chip that is a circuit element, or the like. That is, there is a problem that the reliability of mounting and fixing the leadless component is low.

Further, since the bottom surface pad 7 and the board pad 31 are flat, as shown in FIG. 4 (b), when the solder paste reflows, it flows out of the board pad 31 to be adjacent to the board pad 31. There is a risk of bridging. Furthermore, the solvent of the solder paste is heated and boiled, jumps out of the board pad 31, and becomes the solder ball 11.

In this way, the solder balls 11 jumping out of the board pad 31.
Since the chip carrier 2 and the circuit board 30 are made of ceramic, the solder wettability is poor and it is difficult to adhere to the chip carrier 2 or the circuit board 30. Therefore, when the leadless component is used, there is a problem that the solder ball 11 rolls into the solder outflow portion close to the bridge state and short-circuits between the adjacent board pads.

[Means for solving problems]

In order to solve the above conventional problems, the present invention provides an electrode structure in which a leadless component is mounted on a circuit board 30 by soldering.
As shown in the drawing, the side wall electrode 6 formed on the inner surface of the side wall recess 22 having a bow shape in plan view is provided in parallel with the side wall 21 of the carrier 2, and the inner end portion is connected to the electrode of the circuit element 1 through the connection line. ,
The outer end surface is connected to the sidewall electrode 6.

Then, a bottom recess 23 having an arcuate side view is provided side by side on the periphery of the bottom surface 23 of the carrier 2 so as to be connected to each side wall recess 2, and a bottom electrode 25 is formed on the inner surface of the bottom recess 24. Is.

[Action]

According to the above-mentioned means of the present invention, the bottom electrode 25 has the bottom recess 24.
Since it is formed on the inner surface of the arc shape, the bonding surface for bonding to the solder 10 is large even though the projected area is the same area as the conventional bottom surface pad. Therefore, the soldering strength is increased and the reliability of mounting and fixing the leadless component is improved.

Further, since both the bottom surface electrode 25 and the side wall electrode 6 are formed on the arc-shaped inner surfaces of the bottom surface recess 24 and the side wall recess 22, when the solder paste applied on the substrate pad 31 reflows, the bottom surface is caused by the capillary phenomenon. The electrode 25 and the sidewall electrode 6 are raised and adhered. Therefore, solder flows out of the board pad 31,
Alternatively, the solder balls are less likely to jump out, and therefore, there is less risk of short-circuiting between adjacent substrate pads.

〔Example〕

The present invention will be specifically described below with reference to the drawings. The same reference numerals denote the same objects throughout the drawings.

FIG. 1 is a configuration diagram of an embodiment of the present invention, (a) is a perspective view before mounting, (b) is a partially cutaway side view after mounting, (c) is a perspective view of a main part, and FIG. [FIG. 3] is a side view of a main part of one embodiment of the present invention, (a) is a diagram at the time of mounting, and (b) is a diagram after mounting.

In FIG. 1, a carrier 2 in the form of a small rectangular plate made of ceramics such as alumina is mounted with a circuit element 1 such as a semiconductor chip such as LSI or IC in a stepped rectangular recess 3 provided in the central portion and released. The cover 9 is adhered to the formed upper end surface,
The circuit element is sealed.

On the stepped end face 4 of the stepped rectangular recessed portion 3, an electrode pattern 5 made of a desired number of metal conductor films, which communicates with side wall recessed portions 22 which will be described later and which are arranged in parallel on the side wall of the carrier 2, is radially formed. The connecting wires made of wire are wire-bonded to form inner ends of the electrode patterns 5 and the circuit element 1.
Of the respective electrodes are connected.

Moreover, side walls 21 of the carrier 2 are provided in parallel with side wall recesses 22 having an arcuate shape in a plan view perpendicular to the bottom surface 23, and the inner surface of each side wall recess 22 is perpendicular to the outer end surface of the electrode pattern 5. A side wall electrode 6 made of a metal conductor film to be connected is formed.

As shown in detail in FIG. 1 (c), the bottom surface 23 of the carrier 2
In the peripheral edge of, so as to communicate with each side wall recess 22,
A bottom recess 24 having an arcuate shape in side view is provided, and a bottom electrode made of a metal conductor film connected to the sidewall electrode 6 is provided on the inner surface of the bottom recess 24.
Formed 25. On the other hand, desired conductor patterns are formed on the upper surface of the circuit board 30 made of a ceramic plate, and the bottom surface recessed portion of the carrier 2 is formed at the end of each conductor pattern.
Corresponding to 24, rectangular piece-shaped substrate pads 31 are arranged in parallel.

To mount the leadless component as described above by soldering on the circuit board 30, as shown in FIG. 2A, the solder paste 10A is screen-printed on the upper surface of the board pad 31, and the bottom surface of the board pad 31 is printed. The recesses 24 are aligned, the leadless component is temporarily installed on the circuit board 30, and the circuit board 30 is put in, for example, an infrared heating furnace to be heated.

When heated, as shown in FIGS. 2B and 1B, the solder paste 10A reflows and the solder rises due to the capillary phenomenon and adheres to the bottom electrode 25 and the side wall electrode 6.

At this time, since the bottom surface electrode 25 is formed on the arc-shaped inner surface of the bottom surface recess 24, the wettability of the solder is good, and since the flat surfaces do not come into contact with each other as in the conventional case, the capillary phenomenon easily occurs. Therefore, there is little risk that the flowing solder will flow out of the substrate pad 31, and there will be less risk that solder balls will be generated.

Further, since the bottom electrode 25 is formed in an arc surface, even if the projected area is the same as that of the conventional bottom pad,
The adhesive surface of 10 is larger than the conventional bottom pad, and the soldering strength is strong.

The present invention is not limited to the above-described embodiment, and includes a flat carrier of a hybrid integrated circuit that can be implemented by forming the sidewall electrode 6 and the bottom electrode 25.

〔The invention's effect〕

As described above, the present invention is a leadless component in which a bottom surface recess is provided in communication with a side wall recess on the periphery of the bottom surface of a carrier, and a bottom surface electrode is formed in the bottom surface recess. High soldering strength and high reliability of mounting and fixing to the circuit board. In addition, there is little risk that solder bridges or solder balls will be generated, and there is no risk of short-circuiting between adjacent electrodes or between substrate pads.

[Brief description of drawings]

 FIG. 1 is a configuration diagram of an embodiment of the present invention. (A) is a perspective view before mounting, (b) is a partially cutaway side view after mounting, (c) is a perspective view of essential parts, and FIG. 2 is FIG. 3 is a side view of a main part of an embodiment of the present invention, (a) is a diagram at the time of mounting, (b) is a diagram after mounting, FIG. 3 is a configuration diagram of a conventional example, (a) is a perspective view before mounting , (B) is a perspective view after mounting, FIG. 4 is a partially cutaway side view of a conventional example, (a) is a drawing at the time of mounting, and (b) is a drawing after mounting. In the figure, 1 is a circuit element, 2 is a carrier, 3 is a stepped rectangular recess, 4 is a step end face, 5 is an electrode pattern, 6 is a sidewall electrode, 7 is a bottom pad, 9 is a cover, 10 is solder, and 10A is solder. Reference numeral 11 is a paste, 11 is a solder ball, 21 is a side wall, 22 is a side wall recess, 23 is a bottom surface, 24 is a bottom surface recess, 25 is a bottom surface electrode, 30 is a circuit board, and 31 is a board pad.

Claims (1)

[Claims] 1. A component in which a circuit element (1) is mounted on a carrier (2), which is formed on an inner surface of a side wall recess (22) which is arranged in parallel with a side wall (21) of the carrier (2) and which is arcuate in a plan view. Along with the side wall electrodes (6) connected to the circuit element (1) and the side wall recesses (22), the side wall electrodes (6) are arranged side by side on the periphery of the bottom surface (23) of the carrier (2). , The side wall formed on the inner surface of the bottom surface recess (24) for soldering and connecting to the bottom surface recess (24) in a side view and the board pads (31) juxtaposed on the circuit board (30). A leadless component comprising a bottom electrode (25) connected to the electrode (6).