den-on rework reference process for intel socket...

Den-on Instruments Dic Trading: Intel-2009-5-28

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Den-on Rework Reference Process for Mobile Products Intel Socket rPGA-989Using Den-on BGA rework station RD-500III

*This document shows the whole process on how to repair the Intel socket rPGA-989 using the system associating all the tooling needed to complete the process. All the reflow tools used in the process and recommended from Den-on must be used. Substitutes will alter the process.

Process Steps:

1. PCB loading on the machine PCB holder 2. Removal Process and used tooling 3. PCB solder Pad clean up recommendations’ tool 4. Ball printing process and Alignment 5. Placement 6. Profile used during placement removal process 7. Kit and tooling required for implementation


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1. PCB loading on the machine PCB holder

The picture above shows PCB loaded on the machine XY tables, using all kind of knob to align fix and reduce tension on the PCB.

Important note: It is very important to support the PCB from top and bottom side to prevent warpage, an imperative use of the SB-500 Universal PCB Anti-warp support is advised.

Universal PCB Anti-Warp Support top side

Universal PCB Anti-Warp Support bottom side

Flexible and huge area capability PCB Board Support


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2. Removal Process and used tooling

Since the parameter of the reflow profile recommended by Intel are nearly a linear profile we did use the same profile during placement and removal. The socket can be easily removed automatically using a standard vacuum pad shipped with every single machine 3pcs/set.

Removal Profile for Intel Socket rPGA-989


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3. PCB solder Pad clean up recommendations’ tool Wicking Process Using the cleaning mode - Bottom Heater on Rework Machine

When this button is clicked it changes the RELOW time into 60 sec and the REFLOW top heater temperature into 0 ˚C keeping the bottom heater ON, the purpose of this feature is to keep the bottom heater ON this will keep the PCB warp to allow an easy clean up of the solder residue of the removed component while the board is still on the RD-500III board holder, using the SC-400A solder cleaner to remove the excess solder.

A combination with the RD-500III IR Area heater the cleaning mode on feature on the software when removal process then using the SC-400A SMT solder cleaner will allow an easy fast clean up for narrow spaces avoiding any risks of pad lifting log on website to see the video. By giving the heating element 120 watts of power, this solder cleaner has the power to keep the tip at or near the set temperature during the heaviest SMT continuous cleaning.

The higher power and better recovery result in two significant benefits. First there is much less clogging than with standard desoldering units. Second, there is no need to increase the tip temperature which therefore results in longer tip life. Third the Sc-400 can be plugged directly to the machine using a factory air or independently using an internal double pomp N2 capable.

Note: Den-on does not advice a use of wicking process since the high risk of lifting pads. However and just in case you would like to use the wicking process please see below some precautions.

SC-400 SMT/SMD Solder cleaner


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Wicking Process Using the Steps - Stand alone PCB Pre—Heater PH-3100A

CAUTION: The Nozzle in the RD-500III will still be very hot. Use caution when working in this area. If you prefer to remove the PCB before removing the excess solder, be sure to use gloves as the PCB will be hot after the rework cycle.

While wicking solder off of pads: Using solder wick with solder iron

Always clip off the used portion of the wick; it behaves as a heat sink.

Apply liquid flux to the wick, to minimize sticking of the wick to the pads.

Place the soldering iron on the solder wick off to the edge of the pads being soldered, to heat iron tip and wick prior to desoldering.

Do not let solder iron or wick freeze on pads, to prevent pad lift.

Do not lift the wick up and down on the pads.

Apply very light pressure, similar to writing with a pencil. Soldering is achieved by temperature difference, not by tip pressure.

Apply heat for 2 to 3 seconds after solder melts. Total contact time may be 6-7 seconds. Excess heating causes solder brittleness and may lift pads.

Pb-free hand solder may require soldering iron tips hotter than used for SnPb rework.

Hotter tips allow rework at a pace similar to SnPb rework.

Without hotter tips, desoldering and resoldering is slower.

However, with hotter tips, caution must be used to prevent pad lift.


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4. Ball printing process and Alignment

Ball Printing Process:

Laser Stencil Specification: Thickness :t=0.15, Ball Aperture: ψ0.489, Shape: Round

The jig is inverted once more, the lock cover is removed the part is removed by the rework machine’s vacuum pick for placement from the optics arm.

Precautions:

Never use paste directly from the refrigerator, it takes time for the solder paste to come to working temperature when previously refrigerated see 4hrs for 250g of solder paste.

Never stir solder paste with screw driver this may cause solder spitting during reflow process because of the air transferred into the paste

Always check the date of the manufacturer, depending on solder paste manufacturer the date should be between 6 to 12 months of manufacture

The solder paste is frequently used in rework than in screen printer line so a regular check is advised.

Stencil and component is inserted

into the ball printing jig Insert the Lock cover to prevent the component from moving

Lock the cover using the screw knob

Lock the cover using the L wrench key

The jig is inverted, and paste is applied over the apertures

A mini squeegee prints paste onto the balls, and removes excess paste

Stencil

Stencil Nest

Cover lock

Squeegee


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Alignment After the printing process is finished the printing jig BP-500 is loaded on the optics arm then the component is picked up automatically by clicking on the component pick up button using the vacuum pad. The nozzle must be set before starting the alignment process by twisting the nozzle 45 degrees clockwise on the top heater nozzle adaptor the nozzle used during the tests has a ref P/N: BNZ 52.

Component Pick from the optics arm after a ball printing process

The BP-500 is used to print the solder paste on the component and in the mean time is used as a nest for an easy component pick up


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Using the zoom function then the up and down heater you can align the component. A split function is also available to afford an easy alignment.

5. Placement

Height between PCB/nozzle around 2 to 3 mm. The height is adjusted using the up/down heater, You can also set up an automatic height when developing a profile, it is very important since the profile parameters can change depending on the height of the nozzle


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Nozzle used during placement /removal 52x52mm, a big nozzle was used to create the accurate profile to reduce the delta temp between the entire solder ball and the body of the socket.

Warpage is a big issue with such PCBs so Insight Bottom heater nozzle underneath BGA board area, Den-on machine has a focal heating system from top and bottom so the most heated area could be easily warped so the insight nozzle board support has the function to support this area to prevent warpage.

PCB board support to prevent the PCB from warping, in addition of this the IR heaters have a primordial function to keep a uniform temperature on the PCB and the PCB varying between 120°C≤PCB temperature≤160°C to prevent warpage.

Initial Board temperature function it is very important to use the initial board temperature feature on the software this will allow a preheating of the whole PCB to create a uniform expansion temperature and a stable repeatable profile before starting the reflow process, also recommended by Intel.


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Insight bottom heater board support

Board support brackets with for pins support

SB-500 (Universal PCB anti warp support


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6. Profile used during placement removal process: 5 thermocouples has been used to control the temperature on 4 different corners of the component and component body.

Recommended thermocouples location: Socket- rPGA-989 Thermocouple locations for Rework Profile – Mounted on PCB Pads (Solder Joint) and component body.

Note: In order to create the most accurate profile and controle the whole socket Temp. Intel advice to measure the solder joint from the centre and corners of the socket in order to obtain the socket delta T <15⁰C. This requirement would help to minimize the risk of head and pillow in the solder joint of the socket.

Thermocouples input

TC1 Centre Pad 1

TC5 On the component body frame

TC2 Corner Pad 2 TC4 Centre Pad 4

TC3 Corner Pad 3


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Intel recommended reflow profile parameters for the Socket r-PGA and inspection on Den-on BGA rework station RD-500III

Further to the Intel recommended reflow parameters the profile was developed below the rofile inspected using the Profile Inspection mask file feature on the RD-500III software

Thermocouples plugged on different corners of the socket

Thermocouples plugged on the top on the component and the internal body of the socket

Intel recommended parameters for the reflow of the r-PGA socket


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a. Slope measured in the 5 target point of the socket: 1.8°c/s≤ slope average≤4.4°c/s b. Soak time/temperature: 53s≤Time≤85s_150°c≤Temperature≤217°c (Using the solder

paste...using a different solder paste need a different profile) c. Heat time (time above liquidus 217°s): 82s≤TAL≤109s d. Peak temperature: 236°c≤PT≤248°c e. The 1°c≤Δt≤12°c between the 5 target point of the socket

Important: it is very important to use the initial board temperature feature on the software this will allow a preheating of the whole PCB to create a uniform expansion temperature and a stable repeatable profile before starting the reflow process, also recommended by Intel

Intel recommended parameters for the reflow of the LGA socket

BGA & Socket Rework: Intel Reference Process- Parameter table

Rework Part Type BGAs (and other area packages) Process Socket

Process parameteters based on Sn/4Ag/0.5Cu and Sn/3.5Ag Ball alloys.PCB nominal thickness 0.062-0.093'' (1.6-2.4mm) [LGA sockets:

Validated only 0.062'' PCBs]

Peak Temperature Range 230-245℃ 230-250℃ Time above 217℃ (TA217) 40-120 seconds 40-180 seconds

Maximum Body Temp and Time Not to exceed component supplier max

specification

Delta-T (temp difference) across joints on part while above 217℃

≦10℃ ≦15℃

Except for body temps, all temperatures are measured at

Solder joints

Soak Time, from 150℃ to 217℃ ≦100 sec (Soak time & temp vary with solder paste

selection Rising Ramp Rate below 205℃ 0.5-2.5℃/sec

Critical Rising Ramp Rate between 205℃ and 215℃

0.35-0.75℃/sec

Falling Ramp Rate 0.5-2.0℃/sec Flux applied to Pads on board

Solder paste application None Printed on balls Solder paste Same as used at SMT

Hot air rework machine Den-on RD-500III


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7. Kit and tooling required for implementation

① BNZ 52 x 52 P/I: BNZ-52

② Laser Process Stencil, Any size, For BP-500 reference n: 61-03-03-01 (the ball printing kit come standard with the machine) Thickness 0.15mmAperture 0.489mm Shape Round

③ Insight Bottom Nozzle board support reference n: 61-71-03

④ Board Support Bracket Set RD-500III reference n: 61-61-05

⑤ SC-400ASMT Cleaner to clean the solder residue after removal

⑥ Solder paste used LFM-48U TM-H8 from Almit

⑦ SB -500 Universal PCB board support reference: 60-11-50

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Ball printing kit less stencil shipped with the machine

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Note: All the information in this document has been used to get the job done; changing the material may change the way to proceed on repairing the socket..

For further information: [email protected] or [email protected]

Process developed by: Ajizu Watanabe

Den-on Instruments Dic trading overseas department

Used equipment RD-500III

Ajizu Watanabe

[email protected]

www.denondic.co.jp

Tel: +81-3-3929-6000

Fax: +81-3-3929-7441

den-on rework reference process for intel socket...

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