Sony-Ericsson K750 Service Manual WORKING INSTRUCTION
K750 Working Instructions - electrical
Working Instructions - electrical
Applicable for K750i / K750c
Contents
1 Lead-free soldering................................................................................3
2 BGA equipment reflow profiles.............................................................6
2.1 General........................................................................................6
2.2 Temperature measurement.........................................................6
2.3 Reflow profiles.............................................................................7
3 Replacement of parts.............................................................................8
3.1 Backup capacitor.........................................................................9
3.2 External antenna switch...............................................................9
3.3 Camera connector BtB 30 pin....................................................10
3.4 LCD connector BtB 20 pin.........................................................11
3.5 Keyboard connector BtB 20 pin.................................................12
3.6 SIM reader.................................................................................13
3.7 Battery connector ......................................................................13
3.8 Memory stick Duo reader...........................................................14
3.9 IrDA ...........................................................................................14
3.10 Joystick switch...........................................................................15
3.11 Side key switch..........................................................................15
3.12 Microphone................................................................................16
3.13 Red LED....................................................................................17
Diode/ESD protector ..................................................................18
3.14
3.15 Quartz crystal unit......................................................................19
3.16 Prod adapt circuit/ASIC Tjatte 2 ................................................20
3.17 Prod adapt circuit/ASIC Vincenne .............................................21
3.18 Mini T-top...................................................................................22
4 Revision History...................................................................................23
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K750 Working Instructions - electrical
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K750 Working Instructions - electrical
1 Lead-free soldering
Caution
Keep all contact surfaces clean of dirt and hand grease.
This product is manufactured with lead-free
solder and lead-free components!
During electrical repair, it is critical to make sure
that no lead is introduced.
This symbol indicates that the product is leadfree.
All lead-free PBA’s will be marked with this
symbol.
A lead-free work area must be set up completely
separated from work areas that are used to make
lead repairs.
The lead-free work area must also be clearly
labeled with the lead free symbol as shown in the
adjacent picture.
The items on this desk must remain lead-free.
They must be adequately labeled to make their
lead-free status clearly and easily recognized.
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K750 Working Instructions - electrical
LFS (lead-free solder paste) characteristics:
• High melting point (typically 220°C)
• Low wettability
• High surface tension
• Difficult to spread
• Recommended tip temperature = 370°C
When servicing PBA’s that have been
manufactured with LFS (lead-free solder paste),
LFS must
If not, there is a high risk for unreliable
soldering joints.
be used.
Lead-free solder joints are more difficult to
inspect because they do not have shiny surfaces
like leaded solder joints.
Also, lead-free solder does not flow as well as
leaded solder, so some of the solder pad areas
may remain exposed.
Example of lead-free solder joints.
Example of solder joints with lead.
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K750 Working Instructions - electrical
Example of lead-free solder joints.
Example of solder joints with lead.
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K750 Working Instructions - electrical
2 BGA equipment reflow profiles
2.1 General
This document contains reflow profile recommendations for mobile phones and
similar products.
They are just general recommendations and considerations have to be taken for
every single product.
The solder paste is secondary but could also affect the parameters.
In this document one alloy is specified:
SnAgCu (Lead free) melting point 217°C
2.2 Temperature measurement
At least 4 probes should be used.
They should be placed on components with the highest and lowest thermal mass.
The probes shall be located in the beginning, in the middle and at the end of the
board/panel.
It is recommended that the probes are soldered on the board, but glue and capton
tape could also be used, if necessary.
At least one probe shall be placed in the air or on top of a component.
These values are strongly depending on the BGA replacement equipment.
Nozzle type will be chosen after the outer size of the actual component.
Make sure the nozzle does not affect any nearby placed components.
These values are recommendations and may have to be changed depending on the
type of equipment.
The maximum temperature for any component must not exceed 250
°C.
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K750 Working Instructions - electrical
2.3 Reflow profiles
Sn/Ag/Cu (lead-free)
290
250
Preheat zone
Reflow zone
Cooling zone
260°C
245°C
235°C
200
150
Temperature [ºC]
100
150°C
125°C
50
0
40 80 120 160 200 240 280
Time [Seconds]
Ramp rate < 4°C/sec
Ramp rate cooling zone < 6°C/sec
Time above liquidus 60-150 sec
Minimum temperature 235°C
Maximum temperature 245°C or 260°C* for 10 sec
Bottom heat temperature 125°C-150°C
Total time Appr. 4-7 min
* The higher temperature in case the board has extremely high ∆T.
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