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Hand soldering LCC package

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Robert Scott

Jan 1, 1970
0
I have in the past hand soldered SOIC packages for prototypes using a microscope
and a soldering pencil. But now I am faced with a chip that is only available
in an LCC package - the kind with the contacts under the chip. It only has 8
pins. Is there any hope that I can solder this chip using hobbyist's tools?


Robert Scott
Ypsilanti, Michigan
 
D

DJ Delorie

Jan 1, 1970
0
Sure. Put solder paste on the pcb (very little), place the part, and
use the iron to reflow each pad.

Or, use a hotplate to get all the top-side SMD parts, then an iron for
everything else. I have some leadless resonators I soldered with a
hotplate.
 
H

Hawker

Jan 1, 1970
0
I have been able to solder these with a good Pace "mini wave" tip if the
lands extend out far enough. For IPC-7851 lands there might not be
enough land. For IPC-782 you should be good. The problem is that LLC
parts usually have a ground power pad. This is for thermal dissipation.
Sometimes you can get away with not soldering it, sometimes you can't.

Some of your ability to hand solder this depends on the PCB finish. If
it is HASL or Immersion silver you will have better luck than Immersion
Gold.

Hawker
 
R

Robert Scott

Jan 1, 1970
0
I have been able to solder these with a good Pace "mini wave" tip if the
lands extend out far enough. For IPC-7851 lands there might not be
enough land. For IPC-782 you should be good. The problem is that LLC
parts usually have a ground power pad. This is for thermal dissipation.
Sometimes you can get away with not soldering it, sometimes you can't.

Some of your ability to hand solder this depends on the PCB finish. If
it is HASL or Immersion silver you will have better luck than Immersion
Gold.

Well, the land is under my control because I have not yet laid out the PCB. I
intend to use Advanced Circuits in Colorado to make my prototypes. Should I
order the bare-bones board without soldermask?

I
Robert Scott
Ypsilanti, Michigan
 
R

Robert Scott

Jan 1, 1970
0
...Or, use a hotplate to get all the top-side SMD parts, then an iron for
everything else. I have some leadless resonators I soldered with a
hotplate.

Excuse my ignorance, but what is a hotplate? Are you talking about a kitchen
utensil?


Robert Scott
Ypsilanti, Michigan
 
H

Hawker

Jan 1, 1970
0
No your going to definitely want solder mask on this one.
Is this a typical 0.5mm pitch LLC?

I had assumed you already had a PCB. If you can afford it do Immersion
Silver for this board as HASL, even though it solders better, is often
nto flat enough for good LLC soldering. The biggest problems I have had
with LLCs is opens due to the part not laying flat. For just a few you
should be able to make HASL work, but I wouldn't use it for production
on any board with LLCs, BGAs, or .65mm pitch or finer.

As to your hot plat comment. They are basically industrial versions of
the home hot plate with metal table. Often chemistry folks have these
for keeping things warm. People also have had good success using
convection toaster ovens, especially when used with processes like the
SIPAD process (google SIPAD).

Me I have access to a fully stocked contract manufacture for my stuff so
I only get to the kind of stuff your talking about when I am putzing in
the lab late night and I can't pawn if off on someone else who does it
all day long. My soldering is getting worse and worse as I get lazy.

Hawker
 
B

Ben Jackson

Jan 1, 1970
0
But now I am faced with a chip that is only available
in an LCC package - the kind with the contacts under the chip. It only has 8
pins. Is there any hope that I can solder this chip using hobbyist's tools?

LCC (Ceramic Leadless Chip Carrier) isn't the kind with contacts only
under the chip. The pads extend up to the side, and there is no center
pad. Are you talking about Analog iMEMS devices?

Perhaps you mean QFN or LFCSP, but I don't think those go down to 8 pin.
An LCC land pattern looks huge compared to QFN.
 
D

DJ Delorie

Jan 1, 1970
0
[email protected] (Robert Scott) said:
Excuse my ignorance, but what is a hotplate? Are you talking about
a kitchen utensil?

Yup. You know how your stove has, say, four "burners" on it? So you
can cook four things at once? I've got a single-burner electric
hotplate, normally used in dorms or apartments for cooking one thing
at a time. I just cook circuit boards on it. I have a syringe of
solder paste, and either manually dab it onto all the pads, or etch a
brass stencil to squeegee the paste on.

Hotplate experiments: http://www.delorie.com/pcb/hotplate/
The hotplate: http://www.target.com/gp/detail.html?asin=B0007QCRNU
Brass etching: http://www.delorie.com/pcb/brass/
The idea: http://www.sparkfun.com/commerce/present.php?p=Reflow Skillet
 
M

Mark Harriss

Jan 1, 1970
0
Robert said:
I have in the past hand soldered SOIC packages for prototypes using a microscope
and a soldering pencil. But now I am faced with a chip that is only available
in an LCC package - the kind with the contacts under the chip. It only has 8
pins. Is there any hope that I can solder this chip using hobbyist's tools?


Robert Scott
Ypsilanti, Michigan


I'm soldering a QFN68 pin package by hand:

1. By keeping the component stored in a jar with lots of silica gel and
a moisture indicator, the first samples I was sent made no mention of
the "pop-corning" effect caused by absorbed moisture turning to steam
and cracking the package.

2. Using a 400W stove element hooked to a temperature controller to warm
the board to 120 deg C to preheat the board and dry the component. This
also provides a slowly cooling base to reduce thermal stresses.

3. I made a spring steel clip attached to holes drilled into the edge of
a sheet aluminium base: the clip holds the component in position while
you tack solder a corner and the aluminium base transfers heat from the
hotplate to the board.

4. After a corner has been tacked down with solder and while the board's
still on the hotplate I run a small iron around the edges of the
component drawing a blob of solder as I go to leave a clean join on each
pad.

5. After soldering the hotplate gets turned off to allow cooling down of
the board with a thermocouple monitoring the component temp.



I'm playing around with IR reflow using a toaster oven but I need to get
some extra flux to add to the solder paste as it doesn't seem to flow
too well and lots of small balls of unflowed solder paste show under the
microscope. The IR oven shows promise but always needs reworking at present.
 
R

Robert Scott

Jan 1, 1970
0
..LCC (Ceramic Leadless Chip Carrier) isn't the kind with contacts only
under the chip. The pads extend up to the side, and there is no center
pad. Are you talking about Analog iMEMS devices?.

How did you know? Yes, it is an accelerometer.


Robert Scott
Ypsilanti, Michigan
 
J

jasen

Jan 1, 1970
0
Excuse my ignorance, but what is a hotplate? Are you talking about a kitchen
utensil?

Yeah, a stove "burner" with a flat metal surface.

portable Single burner hotplates are available if your kitchen ventilation
isn't upto the task of removing the smell of hot resin.

Bye.
Jasen
 
D

DJ Delorie

Jan 1, 1970
0
jasen said:
portable Single burner hotplates are available if your kitchen
ventilation isn't upto the task of removing the smell of hot resin.

PLEASE don't use your regular kitchen stuff (or even the kitchen
itself) for PCB work. The chemicals involved in PCB work should never
come in contact with the same utensils you cook food with.

My hotplate is dedicated to PCB assembly, and lives in my office next
to the soldering iron.
 
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