Freescale Semiconductor Application Note AN3150 Rev 1.0, 2/2006 Soldering Recommendations for Pressure Sensor Devices by: Bill McDonald INTRODUCTION SURFACE MOUNT COMPONENTS Pressure sensor devices require the internal cavity containing the silicon transducer to be exposed to ambient in order for the device to function. Exposed cavity packages require special considerations during board assembly to prevent damage to the device during soldering and subsequent cleaning operations. Components can be mounted using solder paste stencil, screen printed or dispensed onto the PCB pads prior to placement of the component. The volume of solder paste applied to the PCB is normally sufficient to secure the component during transport to the subsequent reflow soldering process. Use of adhesives to secure component is not recommended, but where necessary can be applied providing the vent at the underside of the package does not become blocked. This is applicable only to a gauge pressure sensor device. Absolute pressure sensor devices do not have a backside vent so vent blocking is not an issue. Solder pastes are available in variety of metal compositions, particle size and flux types. The solder paste consists of metals and flux required for a reliable connection between the component lead and the PCB pad. Flux aids the removal of oxides that may be present on PCB pads and prevents further oxidation from occurring during the solder process. The use of a No-Clean (NC) flux is recommended for exposed cavity components. Using pressure spray or other methods of cleaning is not recommended. If cleaning of the pcb is performed Water Soluble (WS) flux can be used, but it is recommended the component cavity to be protected by adhesive Kapton tape, vinyl cap or other means prior to the cleaning process to prevent contamination and foreign materials from being introduced into device cavity as result of cleaning processes. Refer to this link for info. Figure 1. Basic Element http://www.stockcap.com/products.asp Figure 2. Port Adapter Ultrasonic cleaning is not recommended as the frequencies can damage wire bond interconnections. Reflow soldering is typically used for surface mount components and accomplished by convection heat from the sides of the reflow furnace utilizing air circulation to produce uniform temperature across the PCB. Hot spots and shielding of the smaller components by adjacent larger components can be minimized thus achieving more reliable solder connection. © Freescale Semiconductor, Inc., 2006. All rights reserved. THROUGH-HOLE (DIP) STYLE COMPONENTS Dual in-line and other styles of through-hole components packages are typically wave soldered where the leads protrude through the circuit board and exposed to a flux bath then immersed into molten solder as the board is passed over a solder wave to create the solder connection. In this application the top board surface and component body are not directly exposed to high temperatures. MPX series pressure sensors with port adapters should not be exposed to temperatures greater than 220°C. The suffix designations for these devices are; AP, GP, DP, AS, GS,ASX or GSX. SOLDERING PRECAUTIONS Wave solder does not typically expose component to excessive temperature, but there may be cases where components are subjected to secondary reflow cycle during double side board assembly. Vapor phase soldering process is not recommended for open cavity devices. There is a potential for liquid to ingress into the cavity or possibility of condensation to form in cavity of the device. IR reflow is not recommended due to potential damage to plastic features as result of radiation heat transfer. MPXA, MPXH, MPXM and MPXV series pressure sensors with port adapters should not be exposed to temperatures greater than 245°C. Suffix designations for these devices are; C, AP, DP and GSX. Refer to the following table for listing of device types and recommended maximum temperature exposure. The reflow temperature profile for surface mount devices must be in accordance with JEDEC STD. 020. Refer to following link for specific profile details. http://www.jedec.org/download/search/jstd020c.pdf Devices provided with a mounting bracket for special applications are to be excluded. AN3150 2 Sensors Freescale Semiconductor REWORK OF SOLDERED COMPONENTS Rework is not recommended, but should it be necessary, maximum temperature exposure for devices should not exceed the limits shown in Table 1 with minimized duration. Table 1. Pressure Sensors Device Number MPX MPXA MPXV Suffix Designation Package Maximum Temperature °C A,D BASIC ELEMENT 245 AP PORT ADAPTER 220 GP PORT ADAPTER 220 DP PORT ADAPTER 220 AS PORT ADAPTER 220 GS PORT ADAPTER 220 ASX PORT ADAPTER 220 GSX PORT ADAPTER 220 A BASIC ELEMENT 245 C PORT ADAPTER 245 GSX PORT ADAPTER 245 G BASIC ELEMENT 245 C PORT ADAPTER 245 DP PORT ADAPTER 245 GP PORT ADAPTER 245 GVP PORT ADAPTER 245 GSX PORT ADAPTER 245 MPXH A BASIC ELEMENT 250 C PORT ADAPTER 250 MPXM A,D BASIC ELEMENT 250 AS,GS PORT ADAPTER 250 AN3150 Sensors Freescale Semiconductor 3 How to Reach Us: Home Page: www.freescale.com E-mail: [email protected] USA/Europe or Locations Not Listed: Freescale Semiconductor Technical Information Center, CH370 1300 N. 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