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CMA3000 Assembly Instructions CMA3000 Series 3-axis accelerometer
CMA3000 Assembly Instructions TABLE OF CONTENTS Subject to changes TN68 Rev.09 PRELIMINARY VTI Technologies Oy www.vti.fi
1 Objective
2 VTI's 3D Stacked Wafer Level Chip-on-MEMS Package (CoM)
ASIC chips are then isolated using a passivation layer. The concept is illustrated in Figure 1. Figure 1. The concept of the CMA3000 component. well as the assembly process, follow the suggested guidelines outlined in this document.
3 CMA3000 CoM Package Outline and Dimensions
are not considered damage and they do not have an effect on solderability. Figure 2. Outline and dimensions for the CMA3000 component mm with ±50 µm tolerance for reference only. Please check the corresponding data sheet for details.
Figure 3. Pin 1 index mark on top of CMA3000.
4 Packing
4.1 Tape and Reel Specifications
Figure 4. Reel dimensions [mm].
CMA3000 Assembly Instructions
4.2 Reel packing and outer box
Figure 7 Reel packing and outer box Subject to changes TN68 Rev.09 PRELIMINARY VTI Technologies Oy www.vti.fi
5 Printed Wiring Board (PWB) Level Guidelines
5.1 PWB layout
2) Solder Mask Defined Pads (SMD). area are highly recomme nded a s tho se would guarantee an o ptimal com ponent pe rformance. CMA3000-A0X_Product_Family_Specification_8282100. Figure 8. Recommended PWB pad layout and dimensions for CMA3000 component.
5.2 Solder Paste
stencil aperture dimensions. Type 3 paste is recommended (grain size 25-45µm).
5.3 Stencil
CMA3000 component are presented in Figure 9. Figure 9. Recommended stencil openings and dimensions for CMA3000 component. Round
CMA3000 Assembly Instructions Note that the stencil openings should always be matched to the selecte d PWD pad de sign and solder paste type for the optimal solder p aste release. F urthermore, th e st encil material and method of forming those have an effect on solder paste release.
5.4 Paste Printing
The p aste printing spee d should b e ad justed according to the solder paste sp ecifications. Care should be taken during paste printing in order to ensure correct paste amount, shape, position, and other p rinting cha racteristics. Negle cting any of these can cause open solder joint s, bri dging, solder balling, or other unwanted soldering results.
5.5 Component Picking
The CMA3 000 comp onent can be pi cked from the carrie r tape using vacuu m nozzle s. Pick u p nozzles a re available i n various sizes and shapes to suit a variety of different component geometries. It is reco mmended to that different pick up nozzle s are teste d to find the best one suited for the purpose. The polarity of the part on tape is presented in section 4.1. In case manual handling of the CMA3000 component is required, special attention should be paid on the handling procedures. Delicate handling is a necessity as exposed silicon and glass surfaces on the CMA3000 component a re very sen sitive to me chanical handli ng. Handlin g with metallic tweezers should be forbidden. However, manual handling is not recommended.
5.6 Component Placement
The CMA3000 co mponents mu st be placed onto P WB a ccurately accordi ng t o their geometry. Reflowable solder spheres provide self-alignment for the component, which will help with accurate positioning. Positioning the packages manually is not recommended. Placement can be done with typical automatic component pick & place machinery capable of placing similar sized components. Recognition of the packages automatically by a vision system enables correct centering of the packages. The Z placement should be carefully controlled as too high force or overdriving during the component placement may damage the component and cause misalignment. Maximum assembly force is 4 N. Locally the mounting pressure should not exceed 1 MPa.
5.7 Reflow Soldering
A forced convection reflow oven is recommended to be used for soldering CMA3000 components. The reflow profile used for solde ring the CMA3000 should always follo w the solder paste manufacturer's specifications and recommended profile. The ramp-up rate should typically be less than 3°C/second. The reflow maximum peak temperature (measured from the component body) should not exceed 260°C and the minimum temperature (measured from the solder joints) should be high er th an 230 °C. The ram p do wn rate sh ould be 6° C/second max. Figure 10 p resents a general forced convection reflow solder profile with the typical phases of a reflow process. Please refer to IPC/JEDEC J-STD-020C table 5-2 and figure 5-1 for det ails. Recommended max number of reflow cycles is 3. Subject to changes TN68 Rev.09 PRELIMINARY VTI Technologies Oy www.vti.fi
Figure 10. Typical convection reflow soldering phases and profile (IPC/JEDEC J-STD-020C table The process window for lead-free soldering is narrower than for traditional eutectic SnPb solders. contains components with vastly different thermal masses. Underfilling of the CMA3000 is not recommended. This can affect on the component performance.
5.8 Moisture sensitivity level (MSL) classification
5.9 Inspection
recommended for ch ecking voids, sold er bri dges, and sh ort-circuits between the solde r j oints. Figure 11. SEM-image of a properly soldered CMA3000 component.
CMA3000 Assembly Instructions
6 Re work Guidelines
There are several rework systems on t he market. Some will heat sol der joint s directly from the sides of component package, while others will direct heat on the t op of component. Occasionally, very rough rework methods are u sed such a s hand placement and heating with a sold ering iron. However, th ese roug h method s are not recommended for CMA300 0 compo nent. It is recommended that the h eat flow of hot-ai r c onvection di rected at the e dge an d u nder th e component body directly to the solder joints and component pad areas would be used. Secondary methods include a ho rizontal flow met hod, a c onduction method, and a cond uction heating from the top of the package.
6.1 Preparations
Prior to the rework process, PWBs and components should be free from m oisture. If ne cessary, baking and drying processes should be performed. The reflow profile for th e component removal should b e similar to the normal r eflow pr ocess. A carefully adjusted reflow profile is e ssential for the successful rework operation. A proper reflow profile should be mea sured with the rmo-couples. During th e refl ow p rofiling, at least the solder joints, the top of the com ponent, and the bottom of the PWB sh ould be mo nitored. If there are other components near the component to be reworked, the temp eratures of th ose should also be monitored. T he b ottom side h eating o f the PWB is re commended in o rder t o redu ce the PWB warpage during the rework operation.
6.2 Component removal
Once the sol der joints have been fully melted, t he component can be carefully removed fro m the PWB. The common rework methods for the component removal can be used, i.e. a vacuum nozzle etc. It is absolutely nece ssary to en sure the co mplete melting of the solde r joints before the component lifting. If the solder joint s are not fu lly melted befo re the lifting ope ration, pad damage may occur on the PWB and the component.
6.3 PWB cleaning
After the compone nt is removed, the pad ar eas of the PWB should be cl eaned usi ng co mmon rework methods. These include the applying of a rework flux, a n excess solder and flux removal using a vacuum solder removal tool or a solder wick and a soldering iron with a wide chisel tip, and the cl eaning of solder pads with al cohol and brush. The PWB clea ning process sh ould be performed gently as too high force or a scrubbing motion can cause pad lifting and trace damage.
6.4 Component reuse
It is not recommended to reuse the component.
6.5 Applying flux or solder paste
Prior to th e placement of a replacement component onto the reworked PWB, solder paste or flux should be applied onto the cleaned PWB pads. Recommended methods for applying solder paste or flux are th e usa ge of a micro-sten cil or di spensing. If the micro-ste ncil i s u sed, it sh ould be cleaned after each paste application to prevent clogging. For the solder paste and the stencil, the same guidelines as for the normal reflow process should be used. The usage of solder paste over mere flux is recommended due to an increased stand-off. Subject to changes TN68 Rev.09 PRELIMINARY VTI Technologies Oy www.vti.fi
CMA3000 Assembly Instructions
6.6 Component placement
An accurate alignment of the component is an important process step although the surface tension of the sol der during the reflow step will help with t he self-alignment. The use of a split-vision alignment system is recommended to ensure the precise alignment of the component to the PWB. The Z pla cement force should be carefully co ntrolled in orde r t o prevent th e solde r b ridging, component damage and misalignment.
6.7 Reflow soldering
The same reflow profile, as for the component removal, can be used for the re-attachment of the replacement component as long a s all solde r joints will fully melt and prop erly wet the co ntact areas. Othe rwise, a new and prope r reflow pr ofile must be dev eloped and measured fro m the solder joints. Note that the reflow profile is always solder paste and flux dependent. The reworked PWBs should be allowed to cool to the room temperature. The PWBs and the components should be inspected after the rework process for possible defects. The use of X-ray inspection techniques can be used to verify the success of the rework process.
7 Hand Soldering Guidelines
Hand soldering of the CM A3000 component with so ldering iron is not re commended. For proto- uses of the CMA3000 component, VT I can provide pre -assembled component on a P WB. For more information on thi s, please find t he document CMA3000-D0X PWB sp ecification 8287500A and CMA3000-D0X P WB sp ecification 8 287600A. T hese can be foun d from the Int ernet at www.vti.fi.
8 Environmental Aspects
VTI Tech nologies re spects enviro nmental value s and thu s its CoM p ackaged a ccelerometer sensors are lead-free and RoHS compatible. VTI Tech nologies’ sensors should be sol dered with lead-free solders in order to guarantee full RoHS compatibility.
9 Effect of the Reflow Soldering
CMA3000 is a factory calibrated three-axis accelerometer. However, reflow soldering may cause acceleration offset shift due to thermal stress induced to the component. Offset shift depends e.g. on the u sed layout d esign, ci rcuit bo ard mate rial and th e m anufacturing process. Offset shift stabilizes typically in 6 h after the reflow and is typically less than 150 mg (1σ). Calibration is not recommended prior the offset has settled. Typical offset settling behavior after the soldering can be seen in Figure 14 below. Subject to changes TN68 Rev.09 PRELIMINARY VTI Technologies Oy www.vti.fi
CMA3000 Assembly Instructions Offset settling -100 -80 -60 -40 -20 100 0 5 10 15 20 25 30 35 Time [h] [mg] Figure 14 Offset settling (N=96) after the reflow Subject to changes TN68 Rev.09 PRELIMINARY VTI Technologies Oy www.vti.fi
CMA3000 Assembly Instructions
10 References
JEDEC / Electronic Industries Alliance, Inc. Moisture/Reflow Sensitivity Classifi cation for Nonhermetic Solid State Surface Mount Devices (J-STD-020D).
11 Document Revision History
Version Date Change Description 0.1 24.01.2008 Initial preliminary release 0.2 29.2.2008 Minor updates 0.3 01.07.2008 Minor updates 0.4 07.07.2008 Minor updates 0.5 10.12.2008 Minor updates 0.6 29.12.2008 Version for launch 0.7 17.6.2009 Packing information added, effect of reflow section 9 updated 0.8 29.6.2009 Recommended max number of reflow cycles (3) added, fig 10 replaced with the one from standard, reference to JEDEC std reflow profile added. 0.9 4.8.2009 Note on the index mark visibility added in p5 VTI Technologies reserves all rights to modify this document without prior notice. Subject to changes TN68 Rev.09 PRELIMINARY VTI Technologies Oy www.vti.fi