JP2003318209A - Fabrication method for semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent defective molding of a resin molding body, thus improving its reliability. <P>SOLUTION: In a fabrication method, a pellet 1 is mechanically and electrically connected to each unit wiring substrate 11 of a multilayered wiring substrate 10, and after resin-molding the pellet 1 group collectively by the resin molding body 28, the multilayered wiring substrate 10 and the resin molding body 28 are divided into parts to fabricate individual BGA.IC. A thick film section 23 is formed in the middle part where the pellet 1 group of the multilayered wiring substrate 10's surface dielectric film 20 is mounted, and a thin film section 21 is formed in its peripheral part. Accordingly, by forming the peripheral part in the thin film section, which is inserted into the mold of the resin molding body, an appropriate air vent flow can be created, thus preventing a void in the resin molding body and a blister in the multi-wiring substrate. Since the surface dielectric film of the BGA-IC can be made thick in the thick film section of the multilayered wiring substrate, dielectric voltage performance can be ensured. Namely, highly reliable BGA.IC with good performance for withstand voltage and for moisture resistance can be fabricated by use of MAP. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a mold array process (mold).
array process. Hereinafter referred to as MAP. ) And a method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art A method of manufacturing a semiconductor device by MAP is
A plurality of semiconductor pellets (hereinafter referred to as pellets) in which an integrated circuit including a semiconductor element is built, and a plurality of unit wiring boards on which electric wiring for electrically taking out the integrated circuit is formed are connected. After bonding the multiple wiring boards to each other and encapsulating these pellets with a resin encapsulant in a lump, the multiple wiring board and the resin encapsulant are cut into unit wiring boards, that is, pellets, and individual semiconductor devices Is a method of manufacturing. Then, in the method of manufacturing a semiconductor device by MAP, the resin sealing body is molded by a transfer molding device.

An MCM (multi-chip module) in which a plurality of chips (pellets) are mechanically and electrically connected to an electric wiring board and these pellets are collectively sealed on the electric wiring board. As an example that mentions, "VLS" issued by Nikkei BP Co., Ltd. on May 31, 1993.
I packaging technology (bottom) "P213 to P253. However, the method of manufacturing a semiconductor device by MAP is
This MCM and package are drastically different in that they are cut into individual products by cutting them into pellets.

[0004]

Generally, in order to secure dielectric strength performance up to a target number of cycles in a temperature cycle test or the like, in a semiconductor device which requires high reliability, an insulating film on the surface of an electric wiring board is used. The solder resist film to be formed needs to be thick. Therefore, in the method of manufacturing a semiconductor device by MAP, by setting the solder resist film of the multiple wiring substrate to be a unit wiring substrate to be thick, a semiconductor device corresponding to high reliability can be manufactured by the method of manufacturing a semiconductor device by MAP. Can be considered.

However, when a resin encapsulant is molded on a multiple wiring board having a thick solder resist film by using a molding die of a normal transfer molding apparatus, the multiple wiring board is swollen and the resin sealing body is It has been clarified by the present inventor that there is a problem that a through void is generated in the inside of.

An object of the present invention is to improve the reliability while preventing the occurrence of defective molding of the resin sealing body.
It is to provide a method for manufacturing a semiconductor device by AP.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0008]

The typical ones of the inventions disclosed in the present application will be outlined below.

That is, a plurality of semiconductor pellets are respectively bonded to a plurality of unit wiring boards of a multiple wiring board, and the semiconductor pellets are collectively resin-sealed by a resin sealing body, and then the multiple wiring board is formed. And a method for manufacturing a semiconductor device in which a resin sealing body is cut into each of the unit wiring boards to manufacture an individual semiconductor device, wherein insulation of an area of the multiple wiring board where the plurality of semiconductor devices is obtained is isolated. The film is set to be thick, and at least a vent-side insulating film is set to be relatively thin in a peripheral portion sandwiched by a mold for molding the resin sealing body in the multiple wiring board. To do.

According to the above-mentioned means, since the insulating film in the area where the semiconductor device is obtained in the multiple wiring board is set thick, the withstand voltage performance of each unit wiring board obtained from the multiple wiring board is increased. Can be increased.
That is, it is possible to improve the withstand voltage performance of all the semiconductor devices obtained from the multiple wiring board. In addition, since the insulating film on the vent side of the peripheral part of the multiple wiring board sandwiched by the resin encapsulation mold is set relatively thin, the air inside the cavity is Therefore, it is possible to prevent the defective molding of the resin encapsulation body, which is caused by the swelling of the multiple wiring board and the generation of the through void inside the resin encapsulation body.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, a semiconductor device manufacturing method according to the present invention is applied to a BGA (Ball Grid Array Package).
Integrated circuit device (hereinafter, BGA / IC)
Say. ) Is manufactured by MAP. As shown in FIG. 1, B by MAP
GA / IC manufacturing method includes pellet preparation step, multiple wiring board preparation step, pellet bonding step, wire bonding step, resin encapsulant molding step, resin encapsulant cutting step, solder ball attaching step and electrical characteristic inspection. It has a process. Hereinafter, BG by MAP according to the present embodiment
The manufacturing method of the A / IC will be described in the order of each step.

The pellet preparation process is constituted by a so-called pre-process of the semiconductor device manufacturing method. That is, in a so-called pre-process in the method of manufacturing a semiconductor device, an integrated circuit including semiconductor elements is built in each pellet portion defined in a matrix shape in the state of a semiconductor wafer. The semiconductor wafer is diced into each pellet portion in the dicing step, whereby the pellet 1 shown in FIG. 2 is manufactured. As shown in FIG. 2, the passivation film 3 is entirely deposited on the active area side main surface of the substrate 2 in which the integrated circuit of the pellet 1 is formed, and the peripheral portion of the passivation film 3 is deposited. , A plurality of electrode pads 4 are arranged and opened in a square frame shape. A back surface coating 5 is applied over the entire main surface of the pellet 1 opposite to the active area side main surface of the substrate 2. The pellet 1 thus configured is supplied to the pellet bonding process.

The multiple wiring substrate 10 for collectively forming a plurality of unit wiring substrates 11 is manufactured in the configuration shown in FIGS. 3 and 4 in the multiple wiring substrate preparing process and supplied to the pellet bonding process. To be done. That is, as shown in FIGS. 3 and 4, the plurality of unit wiring boards 11 are formed in a rectangular flat plate-like multiple wiring board 10.
Are laid out in a matrix.

The multiple wiring board 10 is provided with a base 12 formed in a rectangular flat plate shape, and the base 12 uses a glass / epoxy resin substrate in which glass fibers are impregnated with an epoxy resin and has a multilayer structure (not shown). Formed). A plurality of unit wiring boards 11 are laid out in a matrix on the base 12, and a central portion of an area where each unit wiring board 11 is laid out on one main surface (hereinafter, referred to as an upper surface) of one of the bases 12. In each of the above, a pellet bonding land (hereinafter, referred to as a land) 13 for bonding the pellet 1 is formed in a square having a diameter slightly larger than the outer diameter of the pellet 1. A plurality of internal terminals 14 are arranged outside the four sides of each land 13 on the upper surface of the base 12 in parallel with the respective sides, and each internal terminal 14 is formed in a quadrangular shape having a size capable of wire bonding. ing.

On the other hand, on the lower surface of the base 12, a plurality of external terminals 15 are arranged in a two-row rectangular frame shape inside and outside the peripheral portion of the laid-out area of each unit wiring board 11, respectively. The terminals 15 are each formed in a circular shape having a small diameter. Land 13, internal terminal 14
The external terminal 15 is formed by patterning a copper foil attached to the surface of the base 12 by lithography and etching. The internal terminal 14 arranged on the upper surface of the base 12 and the external terminal 15 arranged on the lower surface of the base 12 are electrically connected to each other by an electric wiring 16 arranged inside the base 12. Electric wiring 1 in which a large number of wires are arranged in an electrically insulated state
6 is formed into a so-called multi-layer wiring structure by patterning each layer of the base 12 formed in the multi-layer structure and then connecting the upper layer and the lower layer to each other by through-hole conductors.

At the end of one of the long sides on the upper surface of the base 12, a plurality of injection port portions 17 are formed so as to correspond to the gates of the transfer molding apparatus described later. The inlet metal part 17 includes the land 13 and the internal terminal 1.
4 and the external terminal 15 are formed.

An insulating film (hereinafter, referred to as a back surface insulating film) 18 made of a solder resist film is uniformly deposited on the lower surface of the base 12 as shown in FIG. 4 (c). Each unit wiring board 11 of the back insulating film 18
Each external terminal 15 is attached to a part corresponding to each external terminal 15 of
A window hole 19 for exposing the main surface (lower surface) of each is opened. The back surface insulating film 18 is formed by applying a solder resist on the lower surface of the base 12 by a screen printing method, so that the lower surface of the base 12 is adhered to the lower surface of the base 12 at the same time.
9 can be patterned.

An insulating film (hereinafter referred to as a surface insulating film) 20 made of a solder resist film is entirely deposited on the upper surface of the base 12, and the thickness of the peripheral portion of the surface insulating film 20 is the thickness of the central portion. It is formed thinner than that. A peripheral surface insulating film having a small thickness (hereinafter referred to as a thin film portion) 21.
Is formed in a rectangular frame shape having a constant width along the four sides of the base 12, and the main surface (upper surface) of each injection mouth portion 17 is formed in a portion of the thin film portion 21 corresponding to each injection mouth portion 17 of the base 12. A window hole 22 for exposing each is opened. The thin film portion 21 is formed by applying a solder resist on the upper surface of the base 12 by a screen printing method, so that the window hole 22 can be patterned simultaneously with deposition on the upper surface of the base 12.

A thick surface central insulating film 23 (hereinafter referred to as a thick film portion) 23 surrounded by the thin film portion 21 is formed in a rectangular shape corresponding to an area including all the unit wiring boards 11. A window hole 24 exposing the upper surface of each unit wiring board 11 corresponding to each land 13 and a window hole 25 exposing the upper surface thereof corresponding to the internal terminals 14 are formed. The thick film portion 23 can be applied thickly in combination with the thickness of the thin film portion 21 by applying a solder resist on the upper surface of the thin film portion 21 by screen printing so as to thicken the window portion 24,
25 can be patterned. In this case,
The thin film portion 21 is formed in advance by a screen printing method with the windows 24 and 25 exposed on the entire surface of the base 12. Note that, for example, after the thick film portion 23 is formed thick in the central portion of the base 12 by the screen printing method, the thin film portion 2 is formed.
1 may be thinly formed on the peripheral portion of the base 12 by a screen printing method.

In FIG. 4 (c), the thickness t of the thin film portion 21 is
When a is 0.025 mm, the thickness tb of the thick film portion 23 is set to 0.075 mm. Incidentally, in this case, the thickness of the base 12 is 0.1 mm, the thickness of the pellet 1 is 0.28 mm, and the thickness of the resin sealing body is 0.7 mm.

In the pellet bonding process, the pellets 1 having the above-described structure are used for the multiple wiring boards 10 having the above-described structure, as shown in FIG.
It is pellet-bonded to the land 13 of No. 1. That is, the back coating 5 side of the pellet 1 is bonded to the land 13 of each unit wiring board 11 by the bonding layer 26 made of silver paste, solder material or the like.

Then, in the wire bonding step, as shown in FIG. 6, the wire 27 is wire bonded between the electrode pad 4 of the pellet 1 of each unit wiring board 11 and the internal terminal 14.

A resin encapsulant is molded in the resin encapsulant molding process on the multiple wiring substrate 10 on which the wire bonding process has been performed. This resin encapsulant molding step is carried out by the transfer molding apparatus 50 shown in FIGS.

As shown in FIG. 7, the transfer molding apparatus 50 includes a pair of upper mold 51 and lower mold 52 which are clamped together by a cylinder device or the like (not shown). A plurality of sets of upper mold cavity recesses 53a and lower mold cavity recesses 53b (however, only two sets are shown in FIG. 8) and a pair of mating surfaces of the upper mold 51 and the lower mold 52. The objects are submerged so as to cooperate with each other to form one cavity 53. The lower mold cavity recess 53b is formed in a rectangular flat plate hole shape having a size to accommodate the multiple wiring board 10, and the upper mold cavity recess 53a is a rectangular flat plate slightly smaller than the lower mold cavity recess 53b. It is formed in the shape of a board hole and is arranged concentrically.

A pot 54 is provided on the mating surface of the lower mold 52, and a cylinder device (not shown) is provided in the pot 54.
The plunger 55 pushed forward and backward is crushed by a tablet as a molding material, and the tablet is inserted so as to deliver a liquid resin obtained by melting the tablet.

On the mating surface of the upper mold 51, a cull 56 is disposed so as to face the pot 54 and is recessed.
One end of each of the plurality of runners 57 is connected to. The other end of each runner 57 has an upper mold cavity recess 53a.
Of the runners 57 are respectively connected to the long sides of the runners 57, and gates 58 are provided at the connection portions of the runners 57 with the upper cavity cavities 53a so that the resin 59 can be injected into the cavities 53.

Although not shown for ease of understanding, an upper heat block and a lower heat block are provided outside the upper mold 51 and the lower mold 52, respectively. An electric heater is provided on the upper and lower heat blocks.
And the pots, culls, runners, and tablets and resins in the cavities of the lower mold 52 are laid to heat. By this heating, the tablets are melted, and the resin formed by melting the tablets is reduced to a predetermined viscosity.

Next, a resin encapsulant molding process using the transfer molding apparatus having the above-described structure will be described.

During transfer molding, the multiple wiring substrate 10 after wire bonding as a work is housed in each lower die 52. Then, the upper mold 51 and the lower mold 5
2. The resin 59, which is obtained by clamping the mold 2 and heating and melting the tablet, is fed by the plunger 55 from the pod 54 and the cull 56 to the respective cavities 53 through the respective runners 57 and the respective gates 58 to be filled therein. become.

By the way, as shown in FIG. 7B, if the thick back surface insulating film 18 ′ and the thick front surface insulating film 20 ′ are uniformly formed on the entire surface of the multi-layer wiring substrate 10, the cavities are The volume of the tee 53 is reduced, and as shown by the broken line arrow in FIG. 7B, the air vent flow 60 is at the air vent side end of the cavity 53 at the mating surface between the upper mold 51 and the lower mold 52. Since the resin is blocked, voids 61 are generated inside the resin 59 of the cavity 53, and the multiple wiring board 10 is swollen.

In this embodiment, as shown in FIG. 7A, the multi-layer wiring substrate 10 has a surface insulating film composed of a thin film portion 21 in the peripheral portion and a thick film portion 23 in the central portion. 20
Since the thin insulating film 18 and the thin back surface insulating film 18 are formed, the reduction in the volume of the cavity 53 is suppressed,
As shown by a dashed arrow in FIG. 7A, a proper air vent flow 62 is formed without being blocked at the air vent side edge of the cavity 53 at the mating surface between the upper mold 51 and the lower mold 52. Since all the air is discharged, voids are not generated inside the resin 59 of the cavity 53 and swelling of the multiple wiring board 10 is not generated.

After the resin 59 is filled in the respective cavities 53 and the liquid resin 59 is thermoset to mold the resin sealing body, the upper mold 51 and the lower mold 52 are opened and the figure The multiple wiring board 10 on which the resin sealing body 28 shown in FIG. 9 is molded is released from the cavity 53 by an ejector pin (not shown). Then, the multiple wiring board 10 on which the resin sealing body 28 is molded is removed from the transfer molding device 50 by a handler (not shown).

As shown in FIG. 9, the resin sealing body 2
The reference numeral 8 is resin-molded so that the upper surface of the multiple wiring board 10 is substantially covered.
4, the pellet 1 and the wire 27 are collectively resin-sealed.

In the resin sealing body cutting step, as shown in FIG. 10, each of the multiple wiring boards 10 whose upper surface is resin-sealed substantially entirely by the resin sealing body 28 as described above is The unit wiring board 11 or the pellets 1 are divided. By this resin sealing body cutting step, the thin film portion 21 of the surface insulating film 20 of the multiple wiring board 10 is cut off, and the surface insulating film 20 of the individually divided unit wiring board 11 is composed of only the thick film portion 23. It will be in a state of being.

As shown in FIG. 11, solder balls 29 are soldered to the external terminals 15 of the unit wiring board 11 in the solder ball soldering step, so that the BGA
-The IC30 has been manufactured.

BGA / IC manufactured as described above
30 is subjected to an electrical characteristic inspection in the electrical characteristic process. At this time, since the surface insulating film 20 of the wiring board (unit wiring board) 11 of the BGA / IC 30 is composed of only the thick film portion 23, it is necessary to secure the dielectric strength performance up to the target number of cycles in the temperature cycle test or the like. You can That is, the BGA IC 30 having high reliability is manufactured.

According to the above embodiment, the following effects can be obtained.

1) By forming a thick surface insulating film on the wiring board of the BGA IC, it is possible to secure dielectric strength performance up to the target number of cycles in a temperature cycle test, etc. An IC can be manufactured.

2) In the method of manufacturing a BGA / IC, the peripheral portion of the surface insulating film of the multiple wiring board sandwiched by the transfer molding device is formed by a thin film portion, so that the resin sealing body for the multiple wiring board is formed. During molding, the volume of the cavity is suppressed from decreasing, a proper air vent flow is formed at the edge of the cavity on the air vent side, and all the air is discharged, so voids may occur inside the resin encapsulant. It is possible to prevent the swelling of the multilayer wiring board.

3) According to the above 2), a through void is formed inside the resin sealing body of the BGA / IC manufactured by dividing the multiple wiring board, or the wiring board (unit wiring board) is swollen. Since it can be prevented from occurring in advance, it is possible to manufacture a BGA / IC having excellent moisture resistance and further improve the reliability of the BGA / IC.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

For example, if the air vent side end portion of the cavity of the mold in the surface insulating film of the multiple wiring board is thin, the air in the cavity can be properly discharged, so that the multiple wiring board As the surface insulating film, at least the surface insulating film at the end portion on the air vent side may be set as a thin film portion.

The back surface insulating film of the multiple wiring board is not limited to be thin throughout, but may be thick throughout. By setting the entire wiring board thicker, the mechanical strength of the multiple wiring board can be increased, so that it is possible to prevent the multiple wiring board from swelling when molding the resin encapsulant, and also to prevent the rear surface of the unit wiring board Since the withstand voltage performance on the side can be enhanced, the reliability of the BGA / IC can be further enhanced.

In the above description, the BGA, which is the field of application of the invention mainly made by the present inventor, was the background.
・ I explained the case where it is applied to the IC manufacturing method.
The present invention is not limited to this, and can be applied to all methods of manufacturing semiconductor devices having other packages.

[0046]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

At least the air vent side of the peripheral portion of the multiple wiring board sandwiched by the molding die for molding the resin sealing body in the multiple wiring board by setting the insulating film thick in the area where a plurality of semiconductor devices are obtained. By setting a relatively thin insulating film, it is possible to prevent the occurrence of defective molding of the resin encapsulant when molding the resin encapsulant while improving the dielectric strength performance of the semiconductor device obtained from the multiple wiring board. Since it can be increased, a semiconductor device having high reliability can be manufactured.

[Brief description of drawings]

FIG. 1 is a BG according to MAP, which is an embodiment of the present invention.
It is process drawing which shows the manufacturing method of A * IC.

FIG. 2 shows a pellet, (a) is a plan view,
(B) is a partially cut front view.

FIG. 3 is a partially omitted plan view showing a multiple wiring board.

4A is a side sectional view taken along the line aa in FIG.
(B) is a side sectional view taken along the line bb of FIG. 3, and (c) is a detailed view of a portion c of (a).

FIG. 5 shows after the pellet bonding process,
(A) is a partially omitted plan view and (b) is a partially cut side view.

6A and 6B show a unit wiring board after a wire bonding step, wherein FIG. 6A is a plan view and FIG. 6B is a sectional view taken along line bb of FIG.

FIG. 7 is a side view of the transfer molding apparatus used in a resin encapsulation molding step, in which some parts are omitted. FIG. 7A shows a case according to the present embodiment, and FIG. It shows the case related to.

FIG. 8 is a plan sectional view in which a cutting line passes through an upper die of the transfer molding apparatus.

9A and 9B are views showing a state after a resin sealing body molding step, wherein FIG. 9A is a plan view and FIG. 9B is a partially cut side view.

FIG. 10 shows a step of cutting a resin sealing body, (a) is a plan view, and (b) is a partially cut side view.

FIG. 11 shows a manufactured BGA / IC,
(A) is a partially cut front view, (b) is an upper half plan view and a lower half bottom view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pellet (semiconductor pellet), 2 ... Substrate, 3 ... Passivation film, 4 ... Electrode pad, 5 ... Backside coating, 10 ... Multiple wiring board, 11 ... Unit wiring board, 1
2 ... Base, 13 ... Land (pellet bonding land), 14 ... Internal terminal, 15 ... External terminal, 16 ... Electrical wiring, 17 ... Injection base part, 18 ... Insulating film (back surface insulating film) made of solder resist film, 19 ... Window hole, 20 ... Insulating film (surface insulating film) made of solder resist film, 21 ... Thin surface peripheral insulating film (thin film portion), 22 ... Window hole, 23
... Thick central surface insulating film (thick film part), 24 ... Window hole exposing the land upper surface, 25 ... Window hole exposing the internal terminal upper surface, 26 ... Bonding layer, 27 ... Wire, 28 ... Resin sealing body , 29 ... Solder balls, 30 ... BGA / IC (semiconductor device), 50 ... Transfer molding device, 51 ... Upper mold, 52 ... Lower mold, 53 ... Cavity, 53a ... Upper mold cavity recess, 53b ... Lower mold cavity Tee recess, 54
... pot, 55 ... plunger, 56 ... Cull, 57 ... runner, 58 ... gate, 59 ... resin, 60 ... air vent flow, 61 ... void, 62 ... proper air vent flow.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasumi Tsutsumi             5-20-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Stock             Ceremony Company within Hitachi Semiconductor Group (72) Inventor Kazuhiko Obata             5-20-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Stock             Ceremony Company within Hitachi Semiconductor Group (72) Inventor Bunji Kuratomi             5-20-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Stock             Ceremony Company within Hitachi Semiconductor Group F term (reference) 5F061 AA01 BA04 CA21 CB13 DA08                       DD14

Claims (5)

[Claims] 1. A semiconductor pellet is bonded to each of a plurality of unit wiring boards of a multiple wiring board, and the semiconductor pellets are collectively resin-sealed by a resin sealing body, and then the multiple wiring board and the resin sealing are formed. A method of manufacturing a semiconductor device in which a stopper is cut into the unit wiring boards to manufacture individual semiconductor devices, wherein an insulating film in an area of the multiple wiring board where the plurality of semiconductor devices are obtained is set thick. In the semiconductor device, at least a vent-side insulating film is set to be relatively thin in a peripheral portion of the multiple wiring board sandwiched by a mold for molding the resin sealing body. Production method. 2. The insulating film on the gate side and the vent side of the peripheral portion of the multiple wiring board sandwiched by a mold for molding the resin sealing body is set to be relatively thin. The method of manufacturing a semiconductor device according to claim 1. 3. The insulating film in the peripheral portion of the multiple wiring board sandwiched by a mold for molding the resin encapsulant is set to be relatively thin overall. Of manufacturing a semiconductor device of. 4. The insulating film is formed of a solder resist, and the insulating film in the semiconductor device acquisition area is thickly formed by applying the solder resist in multiple layers. 2. The method for manufacturing a semiconductor device according to 2 or 3. 5. The unit wiring board is a land, an internal terminal,
5. The method for manufacturing a semiconductor device according to claim 1, wherein the unit wiring board has external terminals and electric wiring formed thereon.