AN936 Mounting Techniques, Lead Forming, and Testing of the MPX Series Pressure Sensors

AN936
Rev 5, 05/2008
Freescale Semiconductor
Application Note
Mounting Techniques, Lead Forming, and Testing of the
MPX Series Pressure Sensors
by: Randy Frank
INTRODUCTION
Freescale’s MPX series pressure sensors are silicon
piezoresistive strain-gauges offered in a chip-carrier package
(see Figure 1). The exclusive chip-carrier package was
developed to realize the advantages of high-speed,
automated assembly and testing. In addition to high volume
availability and low cost, the chip-carrier package offers users
a number of packaging options. This application note
describes several mounting techniques, offers lead forming
recommendations, and suggests means of testing the
MPX series of pressure sensors.
Differential Port Option
Case 344C-01
Figure 1. MPX Pressure Sensor in Chip-Carrier Package
Shown with Port Options
Basic Element
Case 344-15
Suffix AA
Axial Vacuum Port
Case 344G-01
Suffix GVSX
Dual Port
Case 867C-05
Suffix DP
Dual Port
Case 344C-01
Suffix DP
Gauge Port
Case 344B-01
Suffix AP/GP
Stovepipe Vacuum Port
Case 344E-01
Suffix AS/GS
Stovepipe Port
Case 344A-01
Suffix GVS
Axial Port
Case 867F-03
Suffix ASX/GSX
Axial Port
Case 344F-01
Suffix ASX/GSX
Basic Element
Case 867-08
Suffix A/D
Axial Vacuum Port
Case 867G-03
Suffix GVSX
Figure 2. Chip-Carrier and Available Ported Packages
© Freescale Semiconductor, Inc., 2008. All rights reserved.
Gauge Port
Case 867B-04
Suffix AP/GP
Stovepipe Port
Case 867E-03
Suffix AS/GS
MOUNTING TORQUE
.114
.047
0
The sensor package should not be over tightened during
mounting to avoid fractures in mounting flanges of port and
adhesive bond lines. The recommended torque specification
for the sensor packages are as follows:
.125
Port Style
Torque Limit (max)
Single-Sided Port:
Port Down
Port Up
3 in-lbs
3 in-lbs
Dual Port
3 in-lbs
Axial Port
3 in-lbs
.075
.037R
It is recommended that a precision torque wrench be used
to ensure these limits are not exceeded. If a torque wrench is
not available, theses limits equate to approximately 1/4 to
1/2 turn past finger tight contact.
Tightening beyond these limits may result in damage to
package, or affect device performance.
HARDWARE
Screws can be metal or nylon depending on application and
customer preference. A #6 button head screw having head
diameter of approximately 0.250” is recommended. The larger
head diameter will provide force distribution over greater area
minimizing potential of damage to part.
The screws can be threaded directly into mounting surface
or through the board and use a flat washer and nut to secure
the device. A locking compound applied to the threads may be
desired depending on application.
PORT ADAPTERS
Available Packages
Freescale’s chip-carrier package and available ports for
attachment of 1/8” I.D. hose are made from a high
temperature thermoplastic that can withstand temperature
extremes from -50°C to 150°C (see Figure 2). The port
adapters were designed for rivet or 5/32” screw attachment to
panels, printed circuit boards, or chassis mounting.
0
Cell
.021
Figure 3. Examples of Sensors in
Custom Housings
The sensor cell may also be glued directly to a custom
housing or port using many commercial grade epoxies or RTV
adhesives which adhere to grade Valox 420, 30 percent glass
reinforced polyester resin plastic or Union Carbide's Udel®
polysulfone (MPX2300DT1 only). Freescale recommends
using Thermoset EP530 epoxy or an equivalent. The epoxy
should be dispensed in a continuous bead around the caseto-port interface shoulder. Refer to Figure 4. Care must be
taken to avoid gaps or voids in the adhesive bead to help
ensure that a complete seal is made when the cell is joined to
the port. The recommended cure conditions for Thermoset
EP539 are 15 minutes at 150°C. After cure, a simple test for
gross leaks should be performed to ensure the integrity of the
cell to port bond. Submerging the device in water for five
seconds with full rated pressure applied to the port nozzle and
checking for air bubbles will provide a good indication.
Adhesive Bead
Custom Port Adaptor Installation Techniques
The MPX silicon pressure sensor is available in a basic
chip-carrier cell which is adaptable for attachment to
customer-specific housings/ports (Case 344 for 4-pin devices
and Case 867 for 6-pin devices). The basic cell has
chamfered shoulders on both sides which will accept an
O-ring such as Parker Seal's silicone O-ring (p/n#2-015-S469-40). Refer to Figure 3 for the recommended O-ring to
sensor cell interface dimensions.
Figure 4. Case to Port Interface
AN936
2
Sensors
Freescale Semiconductor
TESTING MPX SERIES PRESSURE SENSORS
must be exercised so that force is not applied to the back
metal cap or offset errors can result.
Pressure Connection
STANDARD PORT ATTACH CONNECTION
Testing of pressure sensing elements in the chip-carrier
package can be performed easily by using a clamping fixture
which has an O-ring seal to attach to the beveled surface.
Figure 8 shows a diagram of the fixture that Freescale uses to
apply pressure or vacuum to unported elements.
When performing tests on packages with ports, a high
durometer tubing is necessary to minimize leaks, especially in
higher pressure range sensors. Removal of tubing must be
parallel to the port since large forces can be generated to the
pressure port which can break the nozzle if applied at an
angle. Whether sensors are tested with or without ports, care
= Diameter
Dimensions in
5.72
0.225
MM
Inches
3.81
0.150
2.54
0.100
2.39
0.094
φ 0.36 (0.014) M
φ 0.36 (0.014)
M
A B
M
A B
C
M
M
0.76
0.030
10.16
0.400
3 PL
16.23
0.639
35° ± 2°
Section F-F
C
M
2.03
0.080
14.48
0.570
F
4.55
0.179
3.40
0.134
1.27
0.050
Freescale also offers standard port options designed to
accept readily available silicone, vinyl, nylon, or polyethylene
tubing for the pressure connection. The inside dimension of
the tubing selected should provide a snug fit over the port
nozzle. Installation and removal of tubing from the port nozzle
must be parallel to the nozzle to avoid undue stress which may
break the nozzle from the port base. Whether sensors are
used with Freescale’s standard ports or customer specific
housings, care must be taken to ensure that force is uniformly
distributed to the package or offset errors may be induced.
2.21
2.13
0.087
0.084
3.96
0.156
1.60
0.063
3.96
0.156
6.35
0.250
6.35
0.250
F
13.66
13.51
0.538
0.532
φ 0.36 (0.014)
2 PL
M
A B
M
C
M
0.36 (0.014) A B C
Within
Zone -DZone -D-
Figure 5. Port Adapter Dimensions
AN936
Sensors
Freescale Semiconductor
3
C
R
M
B
-AN
L
1 2 3 4
PIN 1
-T-
TOP CLAMP AREA
SEATING
PLANE
J
D
G
F
4 PL
0.136 (0.005)
NOTES:
DIMENSIONING AND TOLERANCING PER
ASME Y14.5M, 1994.
CONTROLLING DIMENSION: INCH.
DIMENSION -A- IS INCLUSIVE OF THE
MOLD STOP RING. MOLD STOP RING NOT
TO EXCEED 16.00 (0.630).
DIM
A
B
C
D
F
G
J
L
M
N
R
INCHES
MIN
MAX
0.595 0.630
0.514 0.534
0.200 0.220
0.016 0.020
0.048 0.064
0.100 BSC
0.014 0.016
0.695 0.725
30 NOM
0.475 0.495
0.430 0.450
M
T A
M
STYLE 1:
PIN 1.GROUND
2.+ OUTPUT
3.+ SUPPLY
4.- OUTPUT
MILLIMETERS
MIN MAX
15.11 16.00
13.06 13.56
5.08
5.59
0.41
0.51
1.22
1.63
2.54 BSC
0.36
0.40
17.65 18.42
30 NOM
12.07 12.57
10.92 11.43
Case 344-15
All seals to be made on pressure sealing surface.
Figure 6. Chip-Carrier Package
Electrical Connection
The MPX series pressure sensor is designed to be installed
on a printed circuit board (standard 0.100” lead spacing) or to
accept an appropriate connector if installed on a base plate.
The leads of the sensor may be formed at right angles for
assembly to the circuit board, but one must ensure that proper
lead form techniques and tools are employed. Hand or
“needle nose” pliers should never be used for lead forming
unless they are specifically designed for that purpose. Refer
to Figure 7 for the recommended lead form technique. It is
also important that once the leads are formed, they should not
BOTTOM CLAMP AREA
Leads should be securely clamped top and bottom in the area between the plastic body and the
form being sure that no stress is being put on
plastic body. The area between dotted lines represents surfaces to be clamped.
Figure 7. Lead Forming
be straightened and reformed without expecting reduced
durability. The recommended connector for off-circuit board
applications may be supplied by JST Corp. (1-800-292-4243)
in Mount Prospect, IL. The part numbers for the housing and
pins are listed on the following page.
CONCLUSION
Freescale’s MPX series pressure sensors in the chipcarrier package provide the design engineer several
packaging alternatives. They can easily be tested with or
without pressure ports using the information provided.
AN936
4
Sensors
Freescale Semiconductor
CONNECTORS FOR CHIP CARRIER PACKAGES
MFG/Address/Phone
J. S. Terminal Cop.
1200 Business Center Dr.
Connector
Pin
4 Pin Housing: SMP-04V-BCS
SHF-001T-0.8SS
6 Pin Housing: SMP-06V-BC
SHF-01T-0.8SS
Mount Prospect, IL 60056
(800) 292-4243
Hand Crimper YC-12 Recommended
Methode Electronics, Inc.
1300-004
1400-213
Rolling Meadows, IL 60008
(312) 392-3500
1402-213
Requires Hand Crimper
1402-214 Reel
TERMINAL BLOCKS
Molex
22-18-2043
2222 Wellington Court
22-16-2041
Lisle, IL 60532
(312) 969-4550
Samtec
SSW-104-02-G-S-RA
P.O. Box 1147
SSW-104-02-G-S
New Albany, IN 47150
(812) 944-6733
A 0.002
0.175 ±0.001
0.01 x 45×
4 PL
For Vacuum
or Pressure
Source
0.130 ±0.002
For Retaining Ring
(Waldes Kohinoor Inc.
Truarc 5100-31)
0.10
0.036
0.038
30°
R
/ A 0.002 TOTAL
-A0.125 Dia.
0.311
0.44 Dia.
±0.000 ±0.002
-0.001 0.290 Dia.
Dia.
0.648
0.650
Dia.
0.575 Dia.
0.070 Dia.
0.780 Dia.
±0.002
0.670 Dia.
0.015 R
0.02 R
0.04
For O-Ring
(Parker Seals
2-015-S469-40)
0.250
0.245
+0.003
0.525- -0.000
0.60
1.00
1.25 Ref
A
0.0005
Figure 8. O-Ring Test Fixture
AN936
Sensors
Freescale Semiconductor
5
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AN936
Rev. 5
05/2008
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