JP2001085596A - Stepped package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a mounting structure in which sealing can be carried out without being impeded by a soldered part requiring no sealing located contiguously to a sealed part and a heavy MCM package can stand impact when a heavy MCM package is operated. SOLUTION: When a package is designed, a step 1A is provided on the boundary of a region for mounting a soldered part 5 and a region to be bonded with a seal ring 2 and the upper end of the soldered part 5 requiring no sealing is set lower than a sealed part 11. A lead connecting pad is not provided on the lowermost layer of a substrate 1 but a step 1B is provided on the outer circumferential part on the bottom face of the substrate 1 substantially flush with the forward end part of the lead 4 so that the package can be bonded to the surface 13 of the substrate through adhesive 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a component mounting structure at the time of designing and manufacturing a hybrid IC or a multi-chip module (hereinafter, referred to as MCM), and more particularly to a step type package.

[0002]

2. Description of the Related Art Conventionally, when designing and manufacturing a hybrid IC or MCM, an IC is mounted on a substrate called a substrate.
A chip-mounted component such as a bare chip component and a resistor is mounted.The above-mentioned component-mounted substrate is mounted in a package for hermetic sealing with leads, connected by gold wire bonding, and hermetically sealed in a nitrogen gas atmosphere. Was common. However, in order to cope with recent high density and high integration, a structure in which a substrate and a package are integrated has been often used. The hermetic sealing method of the integrated package is such that a seal ring is previously brazed to the package, and the upper surface of the seal ring and the seal cap are subjected to, for example, gold plating as a low melting point sealant, and the seal ring is sealed in a nitrogen gas atmosphere. A seal cap is placed on top of a pair of parallel seam welded roller electrodes, and a current is continuously or intermittently applied between the roller electrodes while moving horizontally to seal by melting a low melting point sealing material such as gold. It is.

[0003]

Here, in order to design a highly reliable, high-density mounting MCM, not only bare chip parts but also soldering parts which need not be sealed because they are hermetically sealed are in the same package as the bare chip parts. May be desirable. FIG. 2 shows the mounting of the bare chip component 6, the chip component 7 such as a resistor, and the soldering component 5 on the substrate integrated package with the seal ring 2 attached.
FIG. 3 shows a state where a seal cap 10 is placed and a roller electrode 12 for parallel seam welding is overlapped on a sealing portion 11. However, as shown in FIG. 2, when the mixed soldering component 5 is close to the sealing portion 11,
There is a case where the electrode 12 hits the soldering component 5 and sealing work cannot be performed. In particular, when designing a high-density mounting MCM, the package size is often large and heavy due to the circuit scale. This is not a problem when incorporating it into a device that is installed on the ground.
To withstand the gravitational acceleration, a heavy MCM package cannot be supported simply by connecting the package lead 4 to the pad 15 of the substrate.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made to realize a mounting structure capable of performing a sealing operation without being disturbed by a sealing-unnecessary soldering component adjacent to a sealing portion, and to realize a heavy MCM. An object of the present invention is to realize a mounting structure in which a package can withstand a shock or the like during operation of the apparatus.

[0005]

A step-type package according to claim 1 is a hybrid IC or a multi-chip module having a structure in which a chip component requiring sealing and a soldering component not requiring sealing are mounted on the same substrate integrated package. In this case, the mounting surface of the solderless component mounting area that does not need to be sealed is made lower than the mounting area of the chip component that requires sealing by making a step on the component mounting surface of the substrate. It is characterized in that it does not become high.

According to the step-type package of the first aspect, since the soldering parts that do not require sealing do not hinder the movement of the roller electrode for parallel seam welding, the soldering parts can also be mounted before sealing, so that the electrical performance evaluation test can be performed. And sealing work can be performed only on the products that pass the test. Also,
For the same reason as above, it does not hinder that the sealing chip component mounting area and the sealing unnecessary soldering component mounting area are arranged close to each other.

According to a second aspect of the present invention, in a hybrid IC or a multi-chip module structured to be mounted on a substrate-integrated package, a step is formed by forming a step so that the outer peripheral lead joint on the bottom of the package is higher than the bottom. The tip of the lead and the bottom surface of the package are substantially flush with each other.

According to the step-type package of the present invention, when the hybrid IC or the multi-chip module is mounted on the substrate, the bottom surface can be adhered to the substrate, so that it is suitable for strong impact and large gravitational acceleration of equipment mounted on an aircraft or the like.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic side view of an MCM showing one embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a substrate of a ceramic base material, in which bonding pads, soldering pads, and lead connection pads are connected by a multilayer wiring structure so that the MCM functions as a system. An alloy seal ring 2 made of Kovar or the like is brazed onto the surface metal foil of the substrate 1 along the outer peripheral portion of the mounting area of the substrate 1 where necessary sealing components (bare chip components, chip components such as resistors) are mounted, and is insulated. By joining the leads 4 held by the lead frame 3 with lead tie bars to the lead connection pads, a substrate integrated package is completed. Here, the lead frame 3 with the insulated lead tie bar can perform an electrical performance evaluation test without disconnecting the leads, so that deformation of the leads during the test can be prevented.

[0010] A soldering component 5 is mounted on the soldering pad of the integrated package by reflow or the like, and a semiconductor bare chip component 6 and a chip component 7 such as a resistor and a capacitor are placed at predetermined locations in a required mounting component mounting area. The bonding pads 8 are used for bonding, and the bonding pads (gold wires) 9 are used to connect the bonding pads. Thereafter, an electrical performance evaluation test as a product is performed, and after passing the specification, hermetic sealing is performed with the seal cap 10 in a nitrogen gas atmosphere.

The hermetic sealing is carried out by horizontally moving the roller electrode 12 for parallel seam while pressing it against the seam welding portion 11, but as shown in FIG. If there is a part 5, a part of the roller electrode 12 will hit the soldered part 5. In a design in which the soldered component 5 is separated from the seam welded portion 11 so as not to collide, a high-density design is hindered. Further, in the method of attaching the soldering component 5 after seam welding, the sealing is performed before the electric performance evaluation test is performed as a product, and it is not practical because electrical adjustment inside the sealing becomes impossible. Therefore, as shown in FIG. 1, a step 1A is provided at the time of designing the package, at the boundary between the soldering component 5 mounting region and the seal ring 2 joining region on the upper surface of the substrate. In the method of providing the step 1A, the substrate surface layer in the mounting area of the soldered component 5 is counted as the Nth layer from the first layer. Here, N is set so that the height of the upper end of the soldering component 5 that does not need to be sealed is not higher than the height of the sealing portion 11 in consideration of the thickness per layer and the difference between the height of the soldering component 5 and the height of the seal ring 2. Decide.

Further, in order to form a package integrated with a substrate, the leads 4 are joined to lead connection pads (not shown) of the substrate 1, but the connection portions withstand thermal stress after mounting on the device. As shown in FIG. 2, a lead 4 formed into a bent shape is used. However, in order to withstand shocks and gravitational accelerations caused by mounting on an airplane or the like, a heavy MCM package cannot be supported only by connecting leads to the pads 15 of the substrate during mounting on an apparatus. Therefore, as shown in FIG. 1, the lead connection pad is not provided at the lowermost layer of the substrate 1, but a step 1B is provided on the outer peripheral portion of the bottom surface of the substrate 1, and the lead connection pad (not shown in the figure) is formed on the intermediate layer. The package 1 can be fixed to the surface 13 of the substrate using the adhesive 14 by making the package bottom surface and the tip of the lead 4 substantially flush with each other by the step 1B at the outer peripheral portion of the substrate 1 bottom surface.

[0013]

According to the present invention, the height of the upper end of the solderless part 5 which does not need to be sealed does not become higher than the height of the sealing part 11, and even if the seal ring 2 and the soldered part 5 are arranged close to each other, the soldering is not performed during seam welding. Since the mounting component 5 does not hinder the movement of the roller electrode 12 for parallel seam, it is possible to design and manufacture a hybrid IC and MCM in which a bare chip component and a soldering component that does not require sealing are mounted in the same package in a high density. . Further, by providing the lead connection pads of the package above the bottom surface, the tip of the lead and the bottom of the package can be made substantially coplanar, and the leads can be connected to the pads of the substrate after bonding the bottom of the package to the surface of the substrate. Therefore, the shock resistance and vibration resistance of the package mounting device are improved. Accordingly, a large and heavy hybrid I which is suitable for mounting on an airplane or the like and which cannot be tolerated only by lead connection.
C, enables MCM design. Further, by bonding the bottom of the package to the surface of the substrate, the heat dissipation can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a step-type package structure MCM showing an embodiment of the present invention.

FIG. 2 is a schematic side view of a package structure MCM having no steps.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 1A Step provided on the upper surface of substrate 1B Step provided at the bottom of substrate 2 Seal ring 3 Lead frame with insulated lead tie bar 4 Lead 5 (No sealing required) Solder parts 5 'Solder part 6 (Requires sealing) ) Semiconductor bare chip 7 (Seal required) Chip component such as resistor and capacitor 8 (Chip fixing) adhesive 9 Bonding wire (gold wire) 10 Seal cap (sealing cover) 11 Seam welded part 12 Roller electrode for parallel seam 13 Substrate surface 14 Adhesive (for fixing package) 15 Substrate pad

Claims (2)

[Claims] 1. In a hybrid IC or a multi-chip module having a structure in which a chip component requiring sealing and a soldering component not requiring sealing are mounted on the same substrate integrated package, a step is formed on a component mounting surface of the substrate. A step characterized by lowering the mounting surface of the solderless component mounting area that does not require sealing than the mounting area of the chip component requiring sealing, so that the top height of the soldering component that does not need to seal does not become higher than the height of the sealing portion. Expression package. 2. A hybrid IC or multi-chip module having a structure mounted on a substrate-integrated package, wherein a step is formed so that an outer peripheral lead joint on the bottom of the package is higher than the bottom, and a tip of the formed lead is formed. And a bottom surface of the package is substantially coplanar.