The temperature curve to teach you how to debug BGA rework station

The temperature curve to teach you how to debug BGA rework station

1, the current commonly used smt tin two namely leaded and unleaded ingredients: lead Pb SN tin silver

copper AG CU.

2, pewter beads Sn63Pb37 melting point 183 °, the melting point of lead-free solder beads

Sn96.5Ag3Cu0.5 217 °

3, adjust the temperature when the temperature line we should be inserted between the bga and PCB,

and to ensure that the tip temperature line exposed portions are inserted into.

4, bumping, BGA surface to be coated in a small amount of help solder paste, stencil, solder balls, planting

tables to ensure clean and dry.

5, to help paste, and paste should be placed in the refrigerator when you save 10 ℃ preservation.

6, before making PCB and BGA board to ensure that no moisture is dried, baked.

7, on international environmental labeling is ROSS, if PCB containing this label, we can also think of this as

a lead-free process PCB done.

8, in the welding BGA, to smear evenly on the PCB help paste, lead-free solder can lead slightly put some

chips.

9, in the welding BGA, pay attention to PCB support, card board card when not too tight, to set aside the

PCB thermal expansion gap.

10, there are major differences between tin and lead-free solder: the melting point is not the same.

(Lead 183 ℃ unleaded 217 ℃) lead good liquidity, unleaded poor. Harmfulness. Lead-free that is

environmentally friendly, non-green lead

11, the role of co-paste of 1> fluxing 2> remove impurities and oxide layer BGA and PCB surface,

so that the welding effect is more good.

12, the bottom of the dark outer heating plate can not be used when cleaning liquid substance to clean,

you can use a dry cloth, tweezers, clean!

Temperature adjustment with: General repair curve is divided into: preheating, heating, constant

temperature, melting soldering, reflow five stages, following an introduction to the testing to curve is

not qualified to adjust, in general we will curve is divided into three parts.

1, preheating and heating section for a part, this part of the role is to reduce the temperature of PCB,

remove moisture to prevent foaming, prevent the heat damage, the general temperature requirements

are: when the second section of the temperature of the test temperature of the tin in (lead: 145~160 C,

there is a high, it means that we set the temperature of the heating temperature is high, can reduce the

temperature of the heating section. If so, can the preheating section and a heating section of the high

temperature or longer time. If it is stored for a longer time is not baked PCB plate can be the first time

to warm up some of the time to bake the board to remove moisture.

2, a constant temperature segment for a part, general our constant temperature temperature setting to

Bishengwen to some lower, this is let the temperature inside the tin ball maintain a slow heating to

achieve constant temperature effect. This part is activated flux and removal to be welded metal surface

oxides and table mask and flux of volatiles, enhance the wetting effect, reducing the temperature of the

role. The general constant temperature section of the actual test tin temperature control requirements

in lead-free: 170~185 DEG C, lead 145~160 DEG C) if high, can reduce the temperature by some, if low

can the temperature heightening some. If the temperature is too long or too short, can be adjusted by

lengthening or shortening the time of constant temperature.

3, fusion welding and welding for a part, this part is to solder and PCB pad good fusion, that in this

section we mainly to achieve is welding peak (lead-free: 235~245 DEG C lead: 210-220 DEG C) if the

measured temperature is high, can reduce the melting welding temperature or shorten the thawing

time welding section. If the measured temperature is low, the temperature of the high melting

temperature or the time of the extension and the fusion welding can be added. Common BGA chip

melt welding time we are limited to 100 seconds, that is, when the temperature is low, we add time,

more than 100 seconds when the temperature is low, we choose to add high melting temperature,

if the 75 seconds to reach the ideal peak then we can change for fourth seconds to 75 seconds.

Such as preheating time is short, it is divided into two kinds of circumstances:

1, after the end of the second paragraph (temperature rise), if the measured temperature is not reached

150, then the target temperature (upper and lower) of the second temperature curve can be appropriately

increased or the constant temperature time is prolonged. After the end of the second section of the

general requirements, the temperature can reach 150.

2, after the end of the second paragraph, the detection temperature can reach 150 degrees, then it

should be extended to third segments (constant temperature). How long will it be for a long time,

and how long it will be.

How to deal with the short time of return welding:

1, can be back to the welding section constant temperature time, a moderate increase in the number of

seconds to increase the number of seconds.

2, if the preheating and back welding time is too long, can be processed by the above method can be

reversed.

3, will adjust the temperature curve, the test again, observe the heating process to detect whether the

temperature is in line with the requirements, the maximum temperature, the maximum temperature,

preheating time, back to the welding time is in line with the requirements, if not, again according to

the above method, until the curve to meet the requirements, you can save this temperature curve

parameters, with.