Shop OBEX P1 Docs P2 Docs Learn Events
Express SMT .8 mm pitch -44 pin (top surface) layout pad and 44 lead PQFP(PG) — Parallax Forums

Express SMT .8 mm pitch -44 pin (top surface) layout pad and 44 lead PQFP(PG)

yarisboyyarisboy Posts: 245
edited 2010-05-04 18:54 in Propeller 1
I have a set of Supertex HV5522 chips that have gull wing leads with a slightly larger footprint than the pad I used from ExpressPCB for the prototype boards. When I designed my version of SM Propeller Platform boards I had no problem putting the Parallax SM propeller gull wing chip down on the same library pad. I've checked the dimensions of the Supertex chip against the data sheet and it is in tolerance. The pitch and lead width is correct. Should I reform the leads on these chips for easier soldering? If I was to do a second run on this board I'd have to un-group the library component and lengthen the pads. If I switch to DipTrace or Eagle will I side step these types of slow-downs down the road?

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
MOORE'S LAW: The capabilities of electronics shall double every 18 months.
cloyd's corollary: Hardware is easy, software is hard.

Comments

  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2010-05-04 05:37
    The Supertex parts certainly do have longer leads but I would leave them as such. I don't know what pad lengths you are using but if you are using solder paste then it shouldn't really be a problem, annoying maybe, but manageable. I did notice the recommended land pattern for the Prop being 13.3mm tip to tip whereas the Supertex part is already 13.65 minimum! Pays to read the datasheets.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    *Peter*
  • yarisboyyarisboy Posts: 245
    edited 2010-05-04 18:54
    Thanks Peter. I was going to hand solder these but with these three I'm going to kick it up a notch and order the correct refrigerated solder paste for the toaster oven. With LMP solder I should be able to put these chips on without damaging the 60/40 joints already on the board. These are non-mission-critical skills and object building projects so its just another ruck in the carpet. Each project ends up being another highlighted section of data sheets pinned up above the project bench. I'm ordering some liquid flux and .015" 63/27 solder soon. When I learn what tools & materials I should of had and which data sheet parts I needed to digest and understand it just make me more thankful that all these people with thirty years experience pay attention to the forum.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    MOORE'S LAW: The capabilities of electronics shall double every 18 months.
    cloyd's corollary: Hardware is easy, software is hard.
Sign In or Register to comment.