U.S. patent application number 09/804148 was filed with the patent office on 2001-09-20 for method for housing sensors in a package.
Invention is credited to Brandl, Manfred.
Application Number | 20010023087 09/804148 |
Document ID | / |
Family ID | 3673925 |
Filed Date | 2001-09-20 |
United States Patent
Application |
20010023087 |
Kind Code |
A1 |
Brandl, Manfred |
September 20, 2001 |
Method for housing sensors in a package
Abstract
There is disclosed a method for housing sensors in a package
and, in particular, housing chemical sensors, flow sensors or
optical sensors in a synthetic package. In a first step, the active
sensor surface of a semiconductor or IC sensor is provided with a
cap forming a hollow space above the active sensor surface and the
sensor is connected with contacts and bond wires. In a second
method step, the package is formed by molding, in particular
injection molding. In a third method step, or simultaneously with
the second method step, the hollow space formed above the active
sensor surface is opened.
Inventors: |
Brandl, Manfred; (Gratwein,
AT) |
Correspondence
Address: |
Pillsbury Madison & Sutro LLP
Intellectual Property Group
Ninth Floor, East Tower
1100 New York Avenue, N.W.
Washington
DC
20005-3918
US
|
Family ID: |
3673925 |
Appl. No.: |
09/804148 |
Filed: |
March 13, 2001 |
Current U.S.
Class: |
438/106 ;
257/E21.502; 438/51; 438/55 |
Current CPC
Class: |
H01L 2224/48247
20130101; H01L 2224/48091 20130101; H01L 2924/00 20130101; H01L
2924/00014 20130101; H01L 2924/00 20130101; H01L 2224/48465
20130101; G01F 1/6845 20130101; H01L 21/56 20130101; H01L
2224/48465 20130101; G01F 15/14 20130101; H01L 2224/48091 20130101;
H01L 2224/48465 20130101; H01L 2224/48247 20130101; H01L 2924/1815
20130101; H01L 2224/48091 20130101 |
Class at
Publication: |
438/106 ; 438/51;
438/55 |
International
Class: |
H01L 021/50; H01L
021/44; H01L 021/48 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 14, 2000 |
AT |
A420/2000 |
Claims
What I claim is:
1. A method for housing a semiconductor or IC sensor having an
active sensor surface, such as a chemical sensor, a flow sensor or
an optical sensor, in a package, which method comprises providing a
cap above said active sensor surface so as to form a hollow space
above said active sensor surface and connecting contact means and
bond wire means to said sensor in a first method step, forming said
package by molding using a molding compound in a second method
step, and opening said hollow space formed above said active sensor
surface in a third method step.
2. A method for housing a semiconductor or IC sensor having an
active sensor surface, such as a chemical sensor, a flow sensor or
an optical sensor, in a package, which method comprises providing a
cap above said active sensor surface so as to form a hollow space
above said active sensor surface and connecting contact means and
bond wire means to said sensor in a first method step, and forming
said package by molding using a molding compound and opening said
hollow space formed above said active sensor surface in a second
method step.
3. A method as set forth in claim 1 or 2, wherein said package is
formed by injection molding.
4. A method as set forth in claim 1 or 2, wherein said hollow space
is opened by sawing after said molding compound has at least
partially set.
5. A method as set forth in claim 1 or 2, wherein said hollow space
is opened by drilling after said molding compound has at least
partially set.
6. A method as set forth in claim 1 or 2, wherein said hollow space
is opened by sawing and drilling after said molding compound has at
least partially set.
7. A method as set forth in claim 1 or 2, wherein said package is
made of a synthetic material.
8. A method as set forth in claim 1 or 2, further comprising
introducing an optical fiber into said hollow space after opening
thereof.
9. A method as set forth in claim 1 or 2, further comprising
providing a frame including contact pin means, connecting said bond
wire means with said frame and embedding said frame in said molding
compound while leaving free said contact pin means.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a method for housing sensors in a
package and, in particular, housing chemical sensors, flow sensors
or optical sensors in a synthetic package.
[0003] 2. Prior Art
[0004] Chemical sensors, like flow sensors or optical sensors, may
be manufactured already in an integrated form in a cost-effective
manner and at a high precision by conventional chip manufacturing
processes. However, such IC sensors or chip sensors subsequently
had to be incorporated in a package, which involved cumbersome
assembly work, whereby the package, as a rule, was either screwed
or glued and the connections to the sensors had to be led out of
the package in a suitable manner. This applied not only to the
electrical connections, but, in the case of chemical sensors, flow
rate sensors or optical sensors, naturally also to line connections
or optical fiber connections, which called for appropriate
additional adaptation work of the packages. Thus, in the production
of such sensors, incorporation in a package constituted a
cost-determining factor for mass production.
SUMMARY OF THE INVENTION
[0005] The invention aims to provide a method of the initially
defined kind, by which the assembly work involved can be
substantially reduced and the necessary connections can, at the
same time, be provided in a cost-effective manner by a few method
steps. To solve this object, the method according to the invention
essentially consists in that, in a first method step, the active
sensor surface of a semiconductor or IC sensor is provided with a
cap forming a hollow space above the active sensor surface and the
sensor is connected with contacts and bond wires, that, after this,
the package is formed by molding, in particular injection molding,
and that, in a third method step or simultaneously with the second
method step, the hollow space formed above the active sensor
surface is opened. In principle, chip molding with a suitable
molding compound is known for many electronic components. Yet, none
of the known methods is suitable for sensors which require to be in
contact with the atmosphere, since after molding the sensor will no
longer be accessible without cumbersome aftertreatment and the risk
of damage to the sensor cannot be excluded in case of subsequent
adaptation work. Due to the fact that, according to the invention,
the active sensor surface of a semiconductor or IC sensor is
provided with a cap forming a hollow space above the active sensor
surface in a fist method step, the respective active sensor surface
is kept free of the molding compound to be applied subsequently.
The provision of bond wires as is common in chip manufacturing may
be accomplished in a simple manner by conventional means, wherein,
by a subsequent molding procedure, in particular an injection
molding procedure, a finished component already comprising all
electrical contacts is immediately provided. Thus, it merely has to
be safeguarded that the active sensor surface in a suitable manner
will again be in contact with the environment, to which end the
hollow space is mechanically opened either during the second method
step simultaneously with the casting-on or molding of the package
or following this second method step. The opening of the hollow
space in a third method step carried out subsequently is preferred
to the simultaneous formation of the opening not the least because
the simultaneous opening of the hollow space requires that the wall
of the cap defining the hollow space be pierced immediately upon
closure of the mold or injection mold, respectively. Since the
injection molding compound, as a rule, has not set at that point of
time, this will cause the previously positioned sensor to be
displaced within the molding compound if no suitable abutment is
provided on the opposite side. If injection molding is performed at
an accordingly higher pressure, it will also have to be ensured in
such a case that the mold will tightly sever the cap in order to
prevent molding compound from being pressed into the hollow space.
In the context of the method according to the invention, it is,
therefore, advantageously proceeded such that the hollow space is
opened by sawing and/or drilling after the at least partial setting
of the molding compound.
[0006] In a particularly simple manner, the package may be made of
suitable synthetics, a number of synthetics having proved to be
suitable in semiconductor technology.
[0007] If an optical sensor is employed, the hollow space
advantageously may be opened by drilling, whereupon an optical
fiber is introduced into the opened hollow space.
[0008] In order to ensure the simultaneous formation of the
electrical contacts with a view to inserting such a sensor provided
with a package into a base or an appropriately prepared printed
circuit board, it may advantageously be proceeded in a manner that
the bond wires are connected with a frame including contact pins
and that the frame is embbed in the molding compound leaving free
the contact pins.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] In the following, the invention will be explained in more
detail by way of the individual method steps schematically
illustrated in the drawing. Therein:
[0010] FIG. 1 illustrates a section through a sensor;
[0011] FIG. 2 is a section through the sensor incorporated in a
package;
[0012] FIG. 3 is a sectional view analogous to FIG. 2,
schematically illustrating an operating tool intended to open the
hollow space;
[0013] FIG. 4 is a view of the sensor upon opening of the hollow
space; and
[0014] FIG. 5 shows an alternative method step for the formation of
the opening of the hollow space in an illustration analogous to
FIG. 2.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0015] FIG. 1 depicts an IC sensor 1 whose sensor surface 2 is
housed on the external side of the IC. In the first method step, a
cap 3 forming a hollow space above the active sensor surface 2 is
put on and electrical contacting is effected via bond wires 4.
[0016] From FIG. 2, the schematically represented package 5 is
apparent after the injection molding procedure. A lead frame 6
comprising the respective bond wires is already integrated in the
package 5, the hollow space 7 left being visible above the active
sensor surface 2.
[0017] In the illustration according to FIG. 3, a saw is indicated
at 8, by which the external wall of the package 5 and the cover cap
3 are appropriately severed so as to create an open connection to
the hollow space 7 containing the active sensor element 2.
[0018] FIG. 4 illustrates the thus produced sensor, showing its
opening 9 which enables the active sensor element 2 contained in
the interior of the package 5 to communicate with the
atmosphere.
[0019] FIG. 5 once again elucidates the method step for the
production of the package under the simultaneous formation of an
opening in an illustration analogous to FIG. 2. With this mode of
operation, the method step of subsequently providing the opening of
the hollow space indicated in FIG. 3 may be obviated. In the
instant configuration, the cap 3 forming the hollow space does
already comprise an interruption, the injection mold thus having to
be modified accordingly. The mold consists of a first mold half 10
and a second mold half 11, wherein the first mold half 10, which is
located adjacent to the cap 3, comprises inwardly projecting webs
12 which are sealingly pressed at the cap outside the interruption
13 of the cap already provided. To this end, the second mold half
11 comprises an accordingly formed pressure element 14 capable of
pressing the webs 12 at the cap 3 in an accordingly tight manner
such that an open access to the hollow space 7 will be formed
immediately upon removal from the mold.
[0020] In the main, it is thus feasible to produce in a
cost-effective manner encapsulated sensors appropriately integrated
in a package by a few method steps suitable for series and mass
production.
* * * * *