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Method for a backside-mounted connector to eliminate special double-sided soldering operations

IP.com Disclosure Number: IPCOM000007147D
Publication Date: 2002-Feb-27
Document File: 9 page(s) / 36K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a backside-mounted connector to eliminate special double-sided soldering operations. Benefits include improved throughput and simplified manufacturing processing.

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Method for a backside-mounted connector to eliminate special double-sided soldering operations

Disclosed is a method for a backside-mounted connector to eliminate special double-sided soldering operations. Benefits include improved throughput and simplified manufacturing processing.

Background

              A-Side refers to one side of a circuit board. B-Side refers to the other side. A and B do not necessarily imply order of assembly. The A-side of a board may have a combination of surface mount (SMT) and through-hole mount (THM) parts on it. The B-side may also have both SMT parts and THM parts on it. In some cases, the B-side may contain only THM parts. In either case, three solder processes are typically required.

1.      Screen print the A-side, place the A-side SMT components, and reflow the solder (see Figure 2).

2.      Insert the A-side THM components and wave solder the B-side (see Figure 3).

3.      Insert the B-side THM components and selectively solder the A-side (see Figure 4).

              A conventional mixed SMT and THM assembly line must efficiently mount connectors so that different ones can be accessed from different sides of the board. Some printed circuit boards (PCBs), such as I/O boards used in servers, must have connections on both sides. These connections may be for various objects, such as cables, or devices such as other circuit boards.

              A process flow for PCBs with THM parts on the B-side (see Figure 1) could utilize the following procedure:

1.           Print solder paste onto the A-side (see Figure 2).

2.           Place the A-side SMT parts.

3.           Reflow the solder, soldering the A-side SMT parts (first soldering process).

4.           Insert the A-side THM parts (see Figure 3).

5.           Wave solder the B-Side and solder the A-side THM parts (second soldering process).
6.           Invert the board.

7.           Insert the B-side THM parts (see Figure 4).

8.           Solder the A-side and attach the B-side THM parts without damaging the A-side parts (third soldering process).

              A process flow for PCBs with A-side SMT and THM parts and B-Side SMT and THM parts (see Figure 5) could utilize the following procedure:

1.           Glue and place the B-side SMT parts (see to Figure 6).

2.           Print solder paste onto the A side (see to Figure 7).

3.           Place the A-side SMT parts.

4.           Reflow the solder, soldering the A-side SMT parts (first soldering process).

5.           Insert the A-side THM parts (see to Figure 8).

6.           Wave solder the B-side, soldering B-Side SMT parts and A-Side THM parts

              (second soldering process).

7.           Invert the board.

8.           Insert the B-side THM parts (see to Figure 9).

9.           Solder the A-side and attach the B-Side THM parts without damaging the A-side parts

              (third solder process).

      The third soldering process in both cases cannot be a reflow solder process because the B-side parts are THM, which typically require wave soldering. However, the process cannot be conventional wave soldering because all the A-side components would be submerged in the molten solder of the wave. Submersion would short all adjacent metal pins and ruin most of the co...