JP2873501B2 - Resin sealing method for semiconductor integrated device in surface mounting of electric wiring board - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin sealing method for a semiconductor integrated device in surface mounting of an electric wiring board.

2. Description of the Related Art In recent years, in the surface mounting of an electric wiring board, for example, a printed wiring board, a semiconductor integrated device is directly mounted on a printed circuit board in a bare state with the increase in density, and the device and the printed circuit board are mounted. Electrical connection with the battery. In this case, the semiconductor integrated element mounted in a bare state on the printed circuit board needs to be sealed with an electrically insulating resin for the purpose of maintaining quality and the like.

The applicant has previously described that, in surface mounting of an electric wiring board, when sealing a semiconductor integrated element mounted in a bare state on the board with a resin, the mounting pattern of the element has the same through-hole pattern as that of the element. Using a stencil, aligning the through hole with the element and forming a gap required for element sealing between the through hole and the element, and then squeezing the liquid sealing resin through the through hole in the gap. (See, for example, JP-A-64-82639).

According to the resin sealing method proposed by the present applicant, I the thickness of the sealing resin layer becomes uniform, and a stable and reliable resin sealing effect is obtained. II The resin sealing with a minimum resin sealing area is possible. The thickness of the III encapsulation resin layer is determined by the effective height of the through-hole, making it easy to control the thickness. Resin sealing enables stable resin sealing irrespective of the size of the element, large or small. V Regardless of the number of mounted elements, one print is performed by one operation based on the printed circuit board. Although advantages such as the ability to process the substrate and excellent productivity are obtained, subsequent research has revealed that there are some problems in terms of uniformity of the thickness of the sealing resin layer and productivity. That is, according to the previously proposed resin sealing method, as shown in FIG. 5A, the filling amount of the resin (b) is larger on the end point side than on the movement start point side of the squeegee (a),
As a result, the contact area between the resin (b) and the stencil (c) becomes large on the squeegee movement end point side during the resin transfer shown in FIG. 5B, and a stringing (d) phenomenon occurs on the end point side. This stringing (d) breaks and disappears when left for a certain period of time in the state shown in FIG. 5B. However, since the amount of stringing is large and it takes a considerable amount of time to break the thread, the time loss is large. Productivity decreases. Further, since the thread break occurs only on the movement end point side, the thread break portion becomes high as shown in FIG.
The thickness of the sealing resin layer is not uniform.

One way to solve such problems is to increase the pressing pressure of the squeegee against the stencil.However, since the liquid resin used for sealing has a high viscosity, even if the pressing pressure is increased, the stencil and the squeegee may be pressed. However, it is not so effective in eliminating the non-uniformity of the resin filling state. If the squeegee moving speed is reduced, the unevenness of the resin filling state tends to be eliminated.However, considering the productivity, the moving speed cannot be reduced so much. It is practically difficult to do.

The present invention has been made to eliminate such a conventional problem.

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, after filling the resin with the squeegee, turning back with the doctor knife, starting from the end point of the squeegee movement end point As a point, when going to the middle point of the travel distance,
The present inventors have found that all the above problems can be solved, and have completed the present invention.

That is, the present invention uses a stencil having the same through-hole pattern as the mounting pattern of the element when sealing the semiconductor integrated element mounted in a bare state on the electric wiring board with a resin, and In the resin encapsulation method, alignment is performed and a gap necessary for element sealing is formed between the through hole and the element, and then a liquid sealing resin is pushed into the gap through the through hole by operating a squeegee. Then, following the indentation and filling of the liquid sealing resin by the squeegee operation, the doctor knife is moved from the movement end point side to the intermediate portion of the stencil through-hole while maintaining the contact state with the stencil, whereby the through-hole of the stencil is opened. The surface mounting of the electric wiring board is characterized in that the filling state of the sealing resin on the squeegee movement start point side and the end point side is substantially uniform, and then the sealing resin is transferred by removing the stencil from the substrate. In According to the resin encapsulation method of a semiconductor integrated device.

EXAMPLE An embodiment of the resin encapsulation method of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 (a) to 1 (b) are schematic explanatory views showing the basic principle of the resin sealing method of the present invention in the order of steps, and show a semiconductor integrated device (2) mounted in a bare state on a printed circuit board (1). A stencil (3) having the same through-hole pattern as the mounting pattern of the element (2) is used for resin sealing.

In a first step shown in FIG. 1 (a), a stencil (3) is fixedly set at a predetermined position of a screen printing machine (not shown), and a substrate (1) is mounted on a slide table (not shown) of the printing machine. 4) The liquid sealing resin (5) is fixedly set on the stencil, and a predetermined amount of the liquid sealing resin (5) is supplied onto the stencil (3).

Next, the above-mentioned printing press is operated, and the through-holes (3
After the alignment of a) with the semiconductor element (2) mounted on the substrate (1) is performed, the stencil (3) is pressed against the surface of the substrate (1), and the stencil (3) is inserted into each through hole (3a). Are concentrically accommodated. This storage state is shown in an enlarged manner in FIG. 2, and a gap (6) required for resin sealing of the element (2) is provided between the through hole (3a) and the element (2) stored therein. ) Is formed.

Next, by operating the squeegee (7), the resin (5) is extruded and filled into the gap (6) in the through hole (3a). This state is shown in FIG. Thereafter, as shown in FIG. 1 (b), the stencil (3) is retreated to the initial position by operating the printing press, and the element (2) sealed with the resin layer (5a) is removed. can get.

As shown in FIG. 3, the resin (5) filled in the space (6) of the through hole (3a) is moved as usual by the conventional method when the squeegee (7) moves at a normal moving speed. On the point side,
Inevitably, there is a tendency to rise (51), and the filling amount increases. Thus, in this state, the resin (5) has through holes (3a).
Transfer from the substrate (1) to the substrate (1) causes a stringing phenomenon on the end point side as described above as a prior art, and this stringing phenomenon causes an uneven thickness of the sealing resin layer. It may cause a decrease in productivity.

In the present invention, in order to solve such a problem,
The following measures are taken as shown in FIGS. That is, as shown in FIG. 4 (a), in the filling operation of the resin (5) by the operation of the squeegee (7), as long as the squeegee (7) is moved in a usual manner, the resin (5) is located at the end point of the movement. ) Inevitably tends to swell (51). Following this filling operation, as shown in FIG. 4 (b), a switching operation with the doctor knife (8) is performed from the end point of the movement. (51) Push the resin back to the middle part of the moving distance. By this pushing back, the filling state of the resin (5) becomes substantially uniform between the end point side and the start point side, and when the resin is transferred in this state, as shown in FIG. The resin breakage is improved between the end point side and the start point side, and substantially no stringing phenomenon occurs in these portions.
On the other hand, at the lower end of the doctor knife (8), stringing (52) occurs due to contact with the pushed back resin, but the threading amount is small due to the small contact area, and the thread breaks in a short time,
Time loss due to stringing is reduced, and productivity can be improved. In addition, since the yarn break occurs at an intermediate point between the moving distances, the resin due to the yarn break is collected at the intermediate point on the upper surface of the resin layer (5a), and flows to both sides after the collection to be substantially flat. The problem of uneven thickness due to yarn breakage can also be solved.

Incidentally, the preferred operating conditions according to the method of the present invention are listed as follows.

Effects According to the method of the present invention, the following effects can be obtained.

By turning back with the doctor knife, the amount of resin filled in the through-hole becomes almost uniform at the squeegee movement start point side and end point side, so at the time of transfer, not only the start point side but also the end point side The phenomenon does not substantially occur.

At the time of transfer, the threading phenomenon occurs between the two points and occurs at the lower end of the doctor knife, but since the amount of threading is small, thread breakage occurs in a short time, and the time loss in waiting for thread breakage is small. Productivity can be improved.

Since the thread break occurs in the middle portion of the sealing resin layer, the resin due to the thread break flows equally to both sides from the middle portion of the layer and is collected. Therefore, the entire thickness of the sealing resin layer is maintained substantially uniformly.

[Brief description of the drawings]

1 (a) and 1 (b) are diagrams for explaining the basic principle of the method of the present invention,
FIG. 2 is a partially enlarged cross-sectional view showing the alignment state between the through hole of the stencil and the element to be sealed, FIG. 3 is a partially enlarged cross-sectional view showing the filling state of the sealing resin into the through hole, Fig. 4 (a) ~
(D) is an explanatory view of a main part of the method of the present invention, and FIGS.
(C) is an explanatory view of the conventional method. In the figure, (1) is a substrate, (2) is a semiconductor integrated device,
(3) is a stencil, (4) is a slide table, (5) is a sealing resin, (6) is a gap, (7) is a squeegee, and (8) is a doctor knife.

────────────────────────────────────────────────── (5) Continuation of the front page (56) References JP-A-63-53955 (JP, A) JP-A-64-82639 (JP, A) JP-A-2-205390 (JP, A) JP-A-2- 299847 (JP, A) JP-A-3-181142 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 23/28-23/30 H01L 21/56

Claims (1)

(57) [Claims] When sealing a semiconductor integrated element mounted in a bare state on an electric wiring board with a resin, a stencil having the same through-hole pattern as the mounting pattern of the element is used. In the resin encapsulation method, alignment is performed and a gap necessary for element sealing is formed between the through hole and the element, and then a liquid sealing resin is pushed into the gap through the through hole by operating a squeegee. Then, following the indentation and filling of the liquid sealing resin by the squeegee operation, the doctor knife is moved from the movement end point side to the intermediate portion of the stencil through-hole while maintaining the contact state with the stencil, whereby the through-hole of the stencil is opened. The surface mounting of the electric wiring board is characterized in that the filling state of the sealing resin on the squeegee movement start point side and the end point side is substantially uniform, and then the sealing resin is transferred by removing the stencil from the substrate. In Resin sealing method of the conductor integrated device.