TECHNET Archives

October 2005

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Condense Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Sender:
X-To:
TechNet E-Mail Forum <[log in to unmask]>
Date:
Wed, 12 Oct 2005 13:16:02 -0400
Reply-To:
TechNet E-Mail Forum <[log in to unmask]>, "Dehoyos, Ramon" <[log in to unmask]>
Subject:
MIME-Version:
1.0
Content-Transfer-Encoding:
quoted-printable
Content-Type:
text/plain; charset="us-ascii"
From:
"Dehoyos, Ramon" <[log in to unmask]>
Parts/Attachments:
text/plain (328 lines)
 

        Thanks Jeff. Is it from pad to pad or from thickest to thinnest
pad areas of the board? I would like to know if HASL plating creates a
planarity problem for QFPs or BGAs assembly for some people in the
industry.
        Regards,
        Ramon


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jeffrey Bush
Sent: Wednesday, October 12, 2005 12:00 PM
To: [log in to unmask]
Subject: Re: [TN] Hasl

We control the thickness from .2 to .9 mils - pad centers.  We use a
HSL-175 horizontal system.

Jeffrey Bush
Director, Quality Assurance and Technical Support

VERMONT CIRCUITS INCORPORATED
  76 Technology Drive - POB 1890
    Brattleboro, Vermont 05302
      Voice: 802.257.4571.21 Fax: 802.257.0011
           http://www.vtcircuits.com
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon
Sent: Wednesday, October 12, 2005 9:06 AM
To: [log in to unmask]
Subject: Re: [TN] Hasl

            
               Thanks for your comments Dr Lee. I would like to know
from the fabricators what is the range in thickness that they can
control on a HASL plating finish. Is it 0.1 to 0.6 mills?  From the
fabricators what is the finest part pitch that they can assemble on
PWBs.
                Thanks for your inputs.
                Ramon
                ME
                410.552.2210
               
    
 

  _____  

From: Lee parker [mailto:[log in to unmask]]
Sent: Tuesday, October 11, 2005 8:10 PM
To: TechNet E-Mail Forum; Dehoyos, Ramon
Subject: Re: [TN] Hasl


Ramon
 
Normally, HASL is the less expensive alternative and thinner.
Consequently by being thinner, it may produce a smaller meniscus which
is usually an advantage. The risk here though is solderability; the
thinner the solder the more likely the occurrence of surface
intermetallics. These issues have been the focus of engineering
attention for years and have become more acute as the feature sizes
diminished. This is why the the industry is migrating from HASL to hard
metal finishes.
 
Best regards
 
Lee
 
J. Lee Parker, Ph.D.
JLP Consultants LLC
804 779 3389  

        ----- Original Message ----- 
        From: Dehoyos, Ramon <mailto:[log in to unmask]>  
        To: [log in to unmask] 
        Sent: Tuesday, October 11, 2005 4:20 PM
        Subject: Re: [TN] Hasl

                Thanks Dr Parker and Richard for your inputs. Comparing
SSSR and
        HASL final plating which are made both using eutectic Tin/Lead
solder
        and other Lead free materials, the end surface is still domed in
the
        middle. So both have  weak gasketing due to their lack in
flatness.
        Setting this issue aside, what are the advantages of one versus
the
        other besides the longer shelf life of SSSR.
                Regards,
                Ramon
                 
	
        -----Original Message-----
        From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem,
Richard
        Sent: Tuesday, October 11, 2005 2:03 PM
        To: [log in to unmask]
        Subject: Re: [TN] Hasl
	
        The idea of the flat surface finish is for both stencil
gasketing to the
        board and for placement accuracy. To form a "perfect brick" of
solder
        paste, there has to be a certain amount of pressure (a lot less
than
        most people think). To prevent squeezout of paste between
stencil and
        board, there has to be good, really good, gasketing or sealing
between
        the stencil and the board surface.
        The problem with HASL, as Dr. Parker stated below, is that the
round
        bump (meniscus) of HASL sticking up above the surface of the pad
on vias
        and on surfaces where there is no accomodating hole in the
stencil
        prevents this tight seal, and allows the paste to squeeze out.
(The
        aperture design is typically slightly smaller than the pad). It
is also
        a problem when you go back and perform pick-n-place, as now you
want to
        place the SMT components onto your perfectly formed bricks of
paste, but
        with about 50-100 grams of pressure. If the paste is not stable
to a
        flat pad, the parts slide all over the place. While some of this
is
        forgiven by the surface tension of the solder in liquidus,
bridges do
        form, components misalign, etc. This is especially critical in a
        no-clean process. If large (relatively) amounts of the solder
paste are
        not "tight to the brick" and fully registered on the pad, the
paste does
        not fully agglomerate into a single solder joint. Separated
solder paste
        does not usually conglomerate back into the central solder joint
during
        reflow. Extraneous solder balls form. This is very bad news if
you did
        not plan on washing them away. 
	
        -----Original Message-----
        From: TechNet [mailto:[log in to unmask]] On Behalf Of Lee parker
        Sent: Tuesday, October 11, 2005 12:03 PM
        To: [log in to unmask]
        Subject: Re: [TN] Hasl
	
        Ramon
	
        After reflowing a soldered surface, you will form a meniscus
which will
        interfere with SMT component placement. To avoid the problem I
suggest a
        flat metal finish such as immersion silver or flash gold (not
ENIG)
	
        Best regards
        Lee
	
        J. Lee Parker, Ph.D.
        JLP Consultants LLC
        804 779 3389
          ----- Original Message -----
          From: Dehoyos, Ramon<mailto:[log in to unmask]>
          To: [log in to unmask]<mailto:[log in to unmask]>
          Sent: Tuesday, October 11, 2005 12:52 PM
          Subject: [TN] Hasl
	
	
	
                      Hi technetters:
                     Is there a fine pitch limit  to the use of HASL
board
        plating
          finish due to its variation in thickness?  Does selective
solder strip
          and reflow plating, SSSR, have a significant advantage over
HASL? Any
          comments relating to platting finish would be greatly
appreciated. I
          thank you for your comments.
                  Ramon
                  ME 
                  410.552.2210
	
          ---------------------------------------------------
          Technet Mail List provided as a service by IPC using LISTSERV
1.8e
          To unsubscribe, send a message to
        [log in to unmask]<mailto:[log in to unmask]> with following text in
          the BODY (NOT the subject field): SIGNOFF Technet
          To temporarily halt or (re-start) delivery of Technet send
e-mail to
        [log in to unmask]<mailto:[log in to unmask]>: SET Technet NOMAIL or
(MAIL)
          To receive ONE mailing per day of all the posts: send e-mail
to
        [log in to unmask]<mailto:[log in to unmask]>: SET Technet Digest
          Search the archives of previous posts at:
	
http://listserv.ipc.org/archives<http://listserv.ipc.org/archives>
          Please visit IPC web site
	
http://www.ipc.org/contentpage.asp?Pageid=4.3.16<http://www.ipc.org/cont
<http://www.ipc.org/contentpage.asp?Pageid=4.3.16<http://www.ipcorg/cont
> 
        entpage.asp?Pageid=4.3.16> for additional information, or
contact Keach
        Sasamori at [log in to unmask]<mailto:[log in to unmask]> or
847-615-7100
        ext.2815
          -----------------------------------------------------
	
        ---------------------------------------------------
        Technet Mail List provided as a service by IPC using LISTSERV
1.8e To
        unsubscribe, send a message to [log in to unmask] with following
text in
        the BODY (NOT the subject field): SIGNOFF Technet To temporarily
halt or
        (re-start) delivery of Technet send e-mail to [log in to unmask]:
SET
        Technet NOMAIL or (MAIL) To receive ONE mailing per day of all
the
        posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the
        archives of previous posts at: http://listserv.ipc.org/archives
Please
        visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for
        additional information, or contact Keach Sasamori at
[log in to unmask] or
        847-615-7100 ext.2815
        -----------------------------------------------------
	
        ---------------------------------------------------
        Technet Mail List provided as a service by IPC using LISTSERV
1.8e To
        unsubscribe, send a message to [log in to unmask] with following
text in
        the BODY (NOT the subject field): SIGNOFF Technet To temporarily
halt or
        (re-start) delivery of Technet send e-mail to [log in to unmask]:
SET
        Technet NOMAIL or (MAIL) To receive ONE mailing per day of all
the
        posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the
        archives of previous posts at: http://listserv.ipc.org/archives
Please
        visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for
        additional information, or contact Keach Sasamori at
[log in to unmask] or
        847-615-7100 ext.2815
        -----------------------------------------------------
	
        ---------------------------------------------------
        Technet Mail List provided as a service by IPC using LISTSERV
1.8e
        To unsubscribe, send a message to [log in to unmask] with
following text in
        the BODY (NOT the subject field): SIGNOFF Technet
        To temporarily halt or (re-start) delivery of Technet send
e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
        To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
        Search the archives of previous posts at:
http://listserv.ipc.org/archives
        Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
        -----------------------------------------------------
	


---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text
in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text
in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

ATOM RSS1 RSS2